Installshield's NA Build

[pcb]

Well, I have a completely unrelated question for you,... how does an engine "know" that it has misfired especially knowing which cylinder. I figure it can't be the electrical flow because it could be leaking to the valve cover somewhere and that give a false reading. The only thing I can think of is the data from the crank and cam position sensors and with a missing power stroke, the gears would accelerate differently but those differences would be in micro or even nano seconds so I dunno. Don't waste your time on it if you don't know, I was just thinking it might be something you'd know off the top of your head.
I've decided to get the non foulers but napa would have to freight them in from Montreal so I'll keep looking,... I don't care if it's cold I wanna do it,...they're only $9.09 plus $7 something for freight. I hunger for data...

 

[Installshield 2]

^^The issue with misfiring is basically a design flaw with most computers of the era...newer computers are much better at it, and older computer were kind of hopeless with it...the flaw, imo, is that p0300 and its specific cylinder derivatives are known as a 'misfire condition'...not a specific type, so therefor just a broad scope of what actually happened...

anyone that has been up against the p0300 titan can probably attest to that...Sometimes you won't notice ANY problem with the engine, but the light comes on...sometimes it'll be missing like crazy, you can hear and feel it, yet no light and no codes...

Our computer is somewhat of a black hole with the community...there is very little specific info for it, so i can only go off of general obd-II design...Generally, any obd-II computer will be simultaneously reading multiple sensors during operation...there is the triggering, used for ignition and fuel timing (not fuel amount, though)...with other sensors simply being used as aux inputs to moniter everything...

p0300, the general misfire code, usually happens when certain sensors throw the computer into a 'anticipation' mode...it'll see certain warnings that will illustrate a misfire possibility, but can't adjust things to fix it as its usually a specific part or sensor not working properly (a coil for example)...some misfires are detected because of exhaust heat changes (a misfire will throw unburned fuel into the exhaust, which will quickly reignite from ambient heat soak)...some misfires are because of the AFR getting messed up (bad injectore, vacuum leak, MAF problem, etc)...and the computer may be aware that its not able to adjust the AFR to what it wants...these usually trip a misfire code, as well as something more related to the actual cause (vac leak, too lean, etc.)

some misfires are detected exactly as you said...the crank sensor can 'see' engine acceleration, and the computer knows that at a certain TPS output...the engine 'should' be accelerating...if that acceleration is interrupted without a change to the TPS...it knows something wrong happened...The TPS is the best sensor to determine which specific cylinder misfired...as it knows the crank position and cam position, and therefor knows which cylinder is stumbling at or around TDC of the compression stroke...So misfires happening under acceleration are usually pretty accurate...while its true that these events are happening very quickly, its actually very slow in 'computer time'...and it has no problem keeping up with it...

the general one happens more at sustained engine speed, or at or around idle...where the tps sensor may be moved around by throttle input...with the tps moving, the crank sensor test isn't as accurate because the engine isn't under a sustained acceleration...

our cars may be a little different in some areas, but in general thats how it works...

 

[Installshield 2]

Ok, so new EGR is in...and the battery was removed to do it, so another reset...

Start and warm up process couldn't be more 'normal'...but, problem was back after fully heated and driving...which is what i kind of expected, as my egr valve wasn't all that dirty...

So, as a temp fix just to not stall...i've retarded the intake cam as far as i could go, didn't touch the exhaust...The same drop to 400'ish rpm occurs at a stop light, but with that much overlap closed its not enough to crap out the engine...after 10 seconds or so, it levels out...So with that evidence, this is all i can go on for now...

SOMETHING is not letting the car fall to idle properly, and its 100% definitely NOT the egr valve...whatever is causing it will only do it in certain situations. Again, i can hang revs at 3,000 rpm while parked for half a minute...let off...idle settles perfectly...the issue seems to be load dependent, so whenever the ecu adjusts things in relation to load...that is when stuff gets messed up...

Its also NOT the cams...as we have a fixed head, and nothing seems to be slipping after countless checks (and still no codes by the way)...but...the cams do play a part in this in which their settings are the difference between a stall...or a 'almost' stall...if it was only the cams, it would always stall...not just some of the time...

So that leaves, from what i can tell, just 3 variables...Its either a problematic IAC now that isn't catching things quite right after it isn't used for a certain period (the IAC isn't doing anything once the engine is off idle)...or its the ECU not having the bandwidth or speed to adjust the IAC 'in time' when the revs fall..again, the ecu may only have this problem after it had to cycle through different load maps, as well as switch in and out of open loop or something...and lastly, it may be a problem with that TB's butterfly idle screw not working quite right with the cams and how slowly the IAC is reacting to a falling rev pattern...

You actually can adjust idle speed...but it takes jumping some ports in the engine bay diagnostic panel while simultaneously making small screw adjustments at the TB...some guys have done it, some haven't...but the FSM may as well be in a different language...and simply adjusting the screw won't change the speed; the computer will simply adjust around it after some more driving...But anyone that has info on what to jump, i'm all ears...

The IAC...balls...i was hoping to not have to touch it...Anyone that has worked on these cars is probably aware that any place Mazda decided to use philips screws...stay the hell away from it...any decent screw driver will slice them up like warm butter...and i don't own an impact driver yet, so i won't be messing with it at least until the engine comes out soon...not to mention, some have made this problem worse by 'cleaning' the IAC...and seeing that replacement is north of $200 for even aftermarket...that kind of sucks...

Last...if its the ecu entirely, and it simply can't react fast enough to cams like this...I'll have one small thing working in my favor...the cam settings dictate the stall or not, as well as the idle 'quality'...but the revs bouncing around at idle are something else...I'm hoping...that with my 7.5LB flywheel going in, that its differences in inertia will allow a slow reaction to not be quite so bad...it'll plummet in revs very quickly, but just a cylinder or two of catch (which it already is doing) may be enough to prevent the stall...

All i can tell so far is that the problem i have...doesn't like intake biased overlap...at all...with a full 5 degrees retard on the intake, stalling isn't a problem even while the computer goes through its tedious learning process...I'm now at an overlap setting no different than the JDM cams i had in before...4 degrees...the twiggys have 12, i pulled 5 from the intake side, and 3 from exhaust...and still have a problem...considering the ONLY real aggressive thing NA twiggys have is large amounts of neutral overlap; its a safe bet it isn't the cams...

so for now...i'm just going to sit tight and schedule my time around the clutch installation...the car is driveable, and still great when not idling...but i'm in no hurry to go buy an expensive part that is just going to be a lot of trouble to install...if anyone can help me out with the idle speed adjustment, i'll do that immediately...

 

[Installshield 2]

Sorry i keep bumping my own thread haha, but its also a log for myself...as once i start messing with a bunch of different things; its a lot easier to keep track of whats been done when i type it down...

just read a great thread on an unrelated engine...but it was all about what certain modifications change for idle...After reading that, i'm now thinking the IAC is actually working ok...and i forgot a very basic principle of cam shafts...

duration and overlap...both have a large effect on idle vacuum...so, in general, ideally i would want to slightly increase idle rpm to make up the difference in vacuum...what i'm seeing, is that simply opening the throttle plate slightly through its stop screw...i can increase the airflow...on its own, thats not exactly what i need (as i need air velocity, not just higher flow, adjusting this will only increase volume but won't necessarily help...

Also, digging around on club protege clarified some things...that with the above info, makes a lot of sense and i might have found a way to fix my problem very quickly...

My IAC must be working...the IAC controls idle throughout the entire start up process...it opens up the bypass, lets more in for cold starts, and since its 'stepped' by the computer...is able to maintain a predetermined idle speed (roughly 1500 rpm for the first minute or so, slowly dropping as the engine heats up)...I'm having this fine, it does this, and everything is normal...

the cam aspect is the other variable...with more than 4 degrees of overlap, and with the 252/254 duration at .006" (forget off the top of my head, but not important)...i'm creating too little vacuum at idle...and it causes the quick drop...The IAC will eventually step through some measures to get that back to normal, but its taking enough time to often result in a stall...and the computer doesn't seem to be in any hurry to 'write that down'...

our TB's have 2 adjustments...on is simply a physical set screw to set the minimum throttle plate position...no electronics, nothing...the other is an adjustment (can't quite tell from the pictures) on the side of the IAC...mazda says NEVER touch the plate screw...but what i can tell, and others have gotten it to work with adjustable gears, is that i can slightly raise the minimum position on the TB...and that will then let the IAC step around it better...i'm seemingly right at the very limits of the IAC (for 750rpm that is)...and i don't need to raise the idle speed, just need to control the amount of air getting in at the current speed...if that makes sense...the current set up is very close to ok, according to the computer, as within a few seconds it reigns in the idle and hold it fine at 750...but the lack of vacuum as the engine descends in revs, and the speed with which the IAC tries to take over...simply isn't right for a set idle of 750rpm...even the clubprotege guys were saying the only time to adjust that plate screw was with a very modified intake manifold or aggressive cams, otherwise it'll just race the engine...

I'm going to carefully mark the current screw position when i get home...and tighten it very slightly to open the TB up a little...again, without manipulating the ecu, i won't be getting any additional rpm...i'm only physically allowing more air in regardless of what the IAC decides to do, and how slowly it decides to react...

 

[Sport23]

Looks like you need to ground the TEN pin on the diagnostic connector and then follow the factory manual.

View attachment Protege idle adjustment.zip

The proper way to adjust idle

 

[Installshield 2]

^awesome info, thanks man...

literally right as you posted that i was reading TheMan's posts in the above thread...Typical of Ed (a great guy, by the way), he is pretty by the books...


EDIT: FINALLY SOME PROGRESS!!!

While i wasn't overly freaked out about adjusting the TAS...I figured i'd first start with the AAS (the other adjustment of which the computer will attempt to learn around)...as i've said before, i'm not too concerned about increasing the rpm of idle...just want it to not choke off so easily (so, i don't mind it idling at 750 rpm, but using marginally more air to hold it there)...

Over lunch i went out to my car with just a screw driver...I tightened the AAS until full stop, without driving a jumper wire (no need to if i'm not changing the idle rpm) and counted the full rotations to reach it (for reference it was about 6.75 full turns)...got in, started it...cold start normal as always...let it warm up...bingo...instant stalling even with the 'new' cam settings...not even a hint of hesitation or hint at catching it...just straight to a stall like i turned the key to off while coasting...with it started again i could feel no intake vacuum at all around the inlet, and the rpm was hovering around 500 rpm consistently...the computer would probably try to adjust that through the IAC anyway, but i don't have time for that haha...

so i opened the screw up with the engine idling...with it tightened all the way, it would barely maintain idle at all...noticed that as i reached its previous position, and kept opening another 2.5 turns or so...i noticed a distinctive change in the intake noise at the filter...it was starting to whistle slightly (you'd only hear if with your face next to it), and placing my hand over the inlet had a much more noticeable amount of vacuum...idle smoothed out...so i drove around again...

ABSOLUTELY NO dipping in rpm off throttle...fell right down to 700-750 perfectly...for the first time in weeks haha...throttle response at warmed up idle at an intersection is now back...if i tap the gas, instantly jumps...no sort of thinking about it or stumbling a little...

I understand this may not be permanent...the computer may fool around with it some...but from what i can tell...the AAS screw physically adjusts the inlet to the IAC...the TAS screw physically adjusts the stop position of the butterfly...so i accomplished what i wanted...i increased idle vacuum now because with the IAC at warmed up 'step', i'm now letting more air physically go through it...since i didn't jump the ecu, this change didn't raise the idle speed...and that wasn't what i needed exactly...

I'll keep you guys posted...

 

[Sport23]

Glad it is working for you! I wouldn't have thought to adjust the AAS without the jumper in order to maintain your current idle RPM. I'll have to try this on my car too. I'm still on stock cams but with with less restrictions in the intake tract I do get low dips and an occasional stall.

I *think* the AAS adjusts a bypas for the IAC but I'm not sure. I'll try to look at a spare throttle body tomorrow.

The TAS adjusts the mechanical stop for the throttle blade. Adjusting it will alter the TPS reading and could cause issues. From what I can tell the TAS is set very close to what the car needs to idle, then minor adjustments are handled by the IAC. The AAS seems to alter how much of a change in idle the IAC can make.

If you have a scan tool could you look at your TPS readings (key on engine off) and let me know what your min and max values are? Also when fully warmed up, how many g/s does your MAF read?

 

[Installshield 2]

^^got home a few hours ago...not one problem on the drive back...so i closed up my overlap...adjusted the intake cam back to 1 degree retard...and the exhaust cam 1 degree advance...crazy awesome lope again...only difference now is it doesn't come close to a stall!!

and yeah, from what i could tell from looking through the TSB's and some other posts on other forums...the TAS does what you said, its a physical adjustment of the throttle plate...and for most purposes, shouldn't be messed with...I never had to, but was literally about to...but the TSB mentioned it directly effects the TPS reading, and you need to reset that...and i don't have the equipment to do so...

that AAS, also from what i can tell, does what you mentioned too...I can't tell exactly from pictures, either...its either a complete bypass of the IAC, to simply let more air in...which kind of makes sense, as the IAC will learn new steps to bring the idle back down to 750rpm...or its an adjustment of the inlet to the IAC...and opening it will simply adjust the timing of the IAC's stepping...

in either case...it worked...at least for now...the engine still idles at 750 rpm, which i never cared about...confirming that this, on its own, will not raise idle rpm without jumping...but now it perfectly catches falling revs...the adjustment seems to make the revs fall to about 1000 rpm...and just sit there for 3 or so seconds...the IAC does its thing, and lowers that to 750...

I'll get some more miles in through the weekend, hopefully by then i'll really know if i'm out of the woods...feel kind of stupid that it may've been something so simple...

 

[Ice88]

Ice...I have an MP3 ecu; have had it in for a few thousand miles with no issues...Also, i never advanced the intake cam...After i first installed the cams, i figured the stalling was simply a product of too much overlap...so i retarded the intake 2 degrees, advanced the exhaust 3 degrees...idle quality was drastically improved...but i only got about 15 miles on the car before i ran into that failing cam plug issue...so the cams came back out, noticed the sheared pin, etc...so it was down for over a week...

then got the cams back in, accidentally switched my gears during the reinstallation...so started it up with something like 17 degrees of overlap...and again it idled well enough, lumpy and everything, but acceptable and at the right rpm...but...drive 10 feet, stalls coming...guaranteed...then i realized i had the gears reversed, so i adjusted everything back now that my valve cover has the window...took 5 minutes...and after those adjustments, it didn't stall once...

Also, i've talked to Orion about it already...He is running stock cam gears, and his stock computer actually handles idle...and it doesn't seem that he is stalling like I am...but also doesn't seem that the microtech has anything to do with it...but i'm not familiar with how most guys run standalones yet anyway...

I realise that you've run the MP3 ECU for a long period of time, I was asking as others with P5s have run the cams seemingly without this issue. As such returning the car to the P5 ECU rules out if its ECU related. It was unlikely but, if its a known configuration that works.

Also dont these cams have 45 degrees of overlap? Ive probably calculated incorrectly or used the wrong values. Its just that the MSF cam has 17.5 degrees of overlap and didnt have this sort of epic idle. (But the MSF does have other factors).

Yes but darryl has higher compression (9.7:1) thus he should have a more stable vacuum.

All i can tell so far is that the problem i have...doesn't like intake biased overlap...at all...with a full 5 degrees retard on the intake, stalling isn't a problem even while the computer goes through its tedious learning process...I'm now at an overlap setting no different than the JDM cams i had in before...4 degrees...the twiggys have 12, i pulled 5 from the intake side, and 3 from exhaust...and still have a problem...considering the ONLY real aggressive thing NA twiggys have is large amounts of neutral overlap; its a safe bet it isn't the cams...

so for now...i'm just going to sit tight and schedule my time around the clutch installation...the car is driveable, and still great when not idling...but i'm in no hurry to go buy an expensive part that is just going to be a lot of trouble to install...if anyone can help me out with the idle speed adjustment, i'll do that immediately...

JDM Cams have 7 degrees (MSF 17.5, MSF TSB 10), US cams are stock 4 degrees.

Whats neutral overlap?

duration and overlap...both have a large effect on idle vacuum...so, in general, ideally i would want to slightly increase idle rpm to make up the difference in vacuum...what i'm seeing, is that simply opening the throttle plate slightly through its stop screw...i can increase the airflow...on its own, thats not exactly what i need (as i need air velocity, not just higher flow, adjusting this will only increase volume but won't necessarily help...

Also, digging around on club protege clarified some things...that with the above info, makes a lot of sense and i might have found a way to fix my problem very quickly...

My IAC must be working...the IAC controls idle throughout the entire start up process...it opens up the bypass, lets more in for cold starts, and since its 'stepped' by the computer...is able to maintain a predetermined idle speed (roughly 1500 rpm for the first minute or so, slowly dropping as the engine heats up)...I'm having this fine, it does this, and everything is normal...

the cam aspect is the other variable...with more than 4 degrees of overlap, and with the 252/254 duration at .006" (forget off the top of my head, but not important)...i'm creating too little vacuum at idle...and it causes the quick drop...The IAC will eventually step through some measures to get that back to normal, but its taking enough time to often result in a stall...and the computer doesn't seem to be in any hurry to 'write that down'...

our TB's have 2 adjustments...on is simply a physical set screw to set the minimum throttle plate position...no electronics, nothing...the other is an adjustment (can't quite tell from the pictures) on the side of the IAC...mazda says NEVER touch the plate screw...but what i can tell, and others have gotten it to work with adjustable gears, is that i can slightly raise the minimum position on the TB...and that will then let the IAC step around it better...i'm seemingly right at the very limits of the IAC (for 750rpm that is)...and i don't need to raise the idle speed, just need to control the amount of air getting in at the current speed...if that makes sense...the current set up is very close to ok, according to the computer, as within a few seconds it reigns in the idle and hold it fine at 750...but the lack of vacuum as the engine descends in revs, and the speed with which the IAC tries to take over...simply isn't right for a set idle of 750rpm...even the clubprotege guys were saying the only time to adjust that plate screw was with a very modified intake manifold or aggressive cams, otherwise it'll just race the engine...

I'm going to carefully mark the current screw position when i get home...and tighten it very slightly to open the TB up a little...again, without manipulating the ecu, i won't be getting any additional rpm...i'm only physically allowing more air in regardless of what the IAC decides to do, and how slowly it decides to react...

A few people have drilled holes in there throttle plate to help with this. Twiggy cams were measure same as stock i.e. at 0.003.

Im kinda happy that my vacuum theory is correct, but saddened that you've had to take so much overlap out

 

[Installshield 2]

oh and also, i'm going to buy one of those bluetooth readers and get the app for my android phone...from what i've seen, they mesh pretty well with these computers...and get the open/closed loop switching correct and everything...which is stuff i'm pretty interested in regardless of this problem...

So with that i'll hopefully be able to read the numbers you're asking for...

 

[Installshield 2]

Ice...wow...those numbers with overlap aren't anything close to what i've seen...but we may be dealing with apples to oranges...

first...neutral overlap may not be the best way to put it; i was meaning the set lobe separation with using factory cam gears...Andrew himself listed that at 11.8 CAM degrees...so if you had NA twiggys with stock cam gears...you were at 11.8 degrees of 'fixed' overlap...Am i reading this info wrong or something? could definitely be a possibility haha...

So if you factor that into degrees of crank rotation...you're at ~24 crank degrees of 'built in' overlap...but most builders keep overlap numbers in terms of cam degrees, so that you know exactly what you're setting when adjusting cam gears...But you're saying 45 degrees? Do you know where that came from? I'm asking because i've been trying to get more info for the twiggys specifically...I know what Andrew and i originally came up with, and A LOT was changed it seems...I guess i won't know exactly until i degree them this spring...but dude...overlap and engine displacement go hand and hand...45 degrees is getting into pretty major v8s...again, as long as we're comparing the same thing...cam overlap and crank overlap are different things...and i'm pretty sure we're comparing overlap numbers at different amounts of lift or something.

I thought Ed's FAQ lists the JDM intake cam and BJ MPS exhaust cam (same cam, different pin location) as 4 degrees overlap...but its just some table of figures for various factory parts...some of which don't line up...it also doesn't specify exactly where that measurement is taken from...so you're saying the US cams are 4 degrees?...and the two Japanese cams are 7 degrees together? and whats this MSF 17.5 degrees thing haha?

As i've said before...concrete data and exactly how the measurements are taken...have plagued this car for years...

thanks for the help, though..if your numbers are right...its way back to the drawing board haha...

oh also, i traded my stock p5 ecu in for my mp3 ecu...it was the spicymsp reflash, so i got money back by sending in my old ecu...as far as the idle stuff, pretty sure i addressed that...but this overlap stuff is interesting...

EDIT: ok, with some input from Daryll...it is a case of apples to oranges...and this at least clears up where some numbers are drastically higher than others...

The NA twiggys, like andrew posted on this forum, are ~12 degrees of overlap at .050" lift...you can factor that into 'seat' overlap, and that is where you'll start seeing numbers way up and over 45 degrees...its the same thing overall, but unless we're talking about identical lift, the numbers won't be comparable...

Ice, do you know if the JDM measurements are at a specific lift number? I'm assuming the 4 and 7 degree numbers are at .050" as well? If so, we're in pretty good shape and all data seems to be accurate...

 

[Ice88]

As far as I know all the mazda cam information we have is measured at 0.003".

When I mentioned the JDM Cams I was referring to the cams that came stock in the FS-ZE and JDM Spec FS-DEs, these have a different intake cam to the US people. The MSF is the Mazdaspeed Cams which was 17.5 degrees overlap (same intake cam just a different exhaust cam), there was a TSB that occured due to the cams running pretty crappily in the cold winters of japan apparently and thus backed out the overlap to a more sedate 10.5 degrees.

In regards to the 45 degrees there numbers I worked out myself, which is why I said there probably wrong as im pretty nub . I forget which numbers I used to calculate it but I did consult google on how to calculate it

EDIT: I should note that if the overlap is at different lift to the advertised duration, thats messed and more then mildly annoying, ill get in contact with edwin see if he knows for sure.

 

[Installshield 2]

Seat overlap (i.e. overlap @ .003" lift) should always be significantly higher than 'usable' overlap...which is generally measured at or around .050" lift...so it looks like that may be some of the hang up with proper info. Also, this 'revised' japanese exhaust cam is complete news to me haha...one of the exhaust cams used in the Japanese MPS 3rd gen sport 20 is simply a FS-ZE intake cam with an adjusted cam pin location. The lobes are identical. Both have 242 degrees of advertised duration, same lift, and used together i'm seeing 7 degrees of overlap on probetalk (i'll find the link again, its book marked)....but now i'm not sure if thats the original exhaust cam, or the revised one....and there is also no mention of if thats seat overlap or at .050"...7 degrees at seat would suggest the cam has absolutely zero usable overlap, by the time the valves start to lift enough to actually move volume...the overlap period would be over...so i'm pretty sure that measurement is for something like .050"...but not positive.

As far as the math...thats actually the easy part...the base specs needed are whats difficult to find.

Overlap at a specific lift = (int. cam duration @ same lift + exhaust duration @ same lift)/4...then subtract the combined lobe separation angle, in cam degrees, between the two cams from that number....that results in overlap at the lift you plugged the numbers in.

you can also calculate overlap in crank degrees by adding the centerline event timing...for example an exhaust cam that closes 4 ATDC and an intake cam that opens 8 degrees BTDC...gives 12 crank degrees of overlap...but again, its stuck at the lift you're getting your centerline's from...

sadly, there is little consistancy when looking at other engines...or even these specific engines...its rarely marked if its overlap in crank or cam degrees (which isn't a huge deal, as its just a factor of 2)...but even more rarely specified at which lift...

For NA twiggy's...i've never seen the actual LSA number. I've seen one for FI twiggys, but i still get very slightly different overlap figures from what he suggested...I've also never seen one for stock or japanese FS cams...I have a number of 113.8 degrees lobe seperation on the FI twiggys, and running the numbers gives approx. .55 degrees of overlap at .050"...so almost no overlap; which lines up with Andrew's posts years ago about the only difference between FI and NA twiggys being built in overlap...I've seen posts from him saying the FI's had around the number i'm getting, but some of his posts have NA's at nearly 13 degrees, some only 10, and some at 11.36, etc...

so until i can get the actual LSA...it doesn't really matter...i can find that though once i properly degree the system with a crank wheel, which will happen during the building of the 'real' engine...so i'm not terribly worried about it for now, just curious...

 

[Installshield 2]

Another day of driving...and everything seems great...last night i put timing back to 1 degree retard on intake cam, 1 degree advance on exhaust...not even close to one stall since, and it settles into idle exactly how i wanted...

so now that this problem is seemingly disappearing, i'm moving on...Ordered the oil adapter plate for my gauges, and am sourcing a single DIN pod for above my receiver...looks like the plate is going to take at least a week to get here (slight back order on that thread pitch, but claim it'll ship tuesday next week)...

So at the end of next week i'll hopefully get that installed, and finally have my gauges...Getting pretty close to the money for a stand alone also...and i've sourced a stand a hoist i need for the clutch installation...Will be a busy next couple of weeks, but hopefully less troubleshooting and more 'fun' work...

Found a crank kit online for $475 also...the FP crank is a solid $150 more than most other mazda crankshafts, which is annoying...and i'm having trouble making sure its a forged unit (i'm pretty sure all FP's were, as that engine was only in 99 and later cars, right?)...

other than that, this weekend i'll be chasing down some extreme clunking that showed up in the front end while it was parked through the cam ordeal...it made no noise, i parked it for a week...getting that sway bar clunk or something in the front left...never messed with the bushings, but they may've finally gave in...i'll see whats up saturday...

 

[Ice88]

Seat overlap (i.e. overlap @ .003" lift) should always be significantly higher than 'usable' overlap...which is generally measured at or around .050" lift...so it looks like that may be some of the hang up with proper info. Also, this 'revised' japanese exhaust cam is complete news to me haha...one of the exhaust cams used in the Japanese MPS 3rd gen sport 20 is simply a FS-ZE intake cam with an adjusted cam pin location. The lobes are identical. Both have 242 degrees of advertised duration, same lift, and used together i'm seeing 7 degrees of overlap on probetalk (i'll find the link again, its book marked)....but now i'm not sure if thats the original exhaust cam, or the revised one....and there is also no mention of if thats seat overlap or at .050"...7 degrees at seat would suggest the cam has absolutely zero usable overlap, by the time the valves start to lift enough to actually move volume...the overlap period would be over...so i'm pretty sure that measurement is for something like .050"...but not positive.

The sport 20 had the same cams as teh JDM spec FS-DE which had 7 degrees of overlap. It has the same exhaust cam as you guys do. Its the Mazdaspeed Famila (MSF) that has the trick exhuast cam. The later TSB cam I believe is the intake cam repinned 178 degrees or something and has 10.5 degrees overlap. What gets me is if the numbers are at .050 then that means that the original MSF cam was wilder then the twiggy cams by 5 degrees.

Ill let you know what the TheMAN says about the overlap measuremants. Id like to work this out .

EDIT: Oh! and I have a friend whom just pulled apart an FP. Hes using the block for a table, let me see if he still has the crank. Not sure what shipping will be like though?

EDIT 2: He still has the crank.

 

[Installshield 2]

^^awesome man, pm me the info to get ahold of him (if he's a member) or email or something. Do you know how many miles are on it? Not a big deal, as its looking like some options may involve removing some arm journals anyway...

but back to the japanese cams...So if you run a JDM intake cam...and a revised MSF exhaust cam (the ZE intake cam repinned, like we mentioned, which i'm guessing is what i own)...thats 10.5 degrees of overlap at an unkonwn lift, right?

thats pretty nuts...as that is exactly what i pulled out of my car to put twiggy's in...I know the duration is higher on the twiggy's...but i was always under the impression the only really aggressive spec twiggy's had was in terms of overlap...and the idle quality at factory cam gear spec, for the twiggys...was immediately apparent...i'd just be surprised that only a degree or so more overlap, and 10 degrees more duration...would take a completely stock idle (you'd never know my engine had hotter cams than stock)...and lump it out to no end...

so just in terms of what i'm noticing, and the possibilty Mazda had some other 'version' that made 17.5 degrees of overlap at lift relevant to what we have in front of us...i don't know what to say haha...there is almost no car i've ever sat in that would idle like this does...I guess its possible, and that led to the TSB and replacement...but if they really had a factory cam that pushed overlap that high...thats simply crazy imo...

Also...i'm seeing through testing...that it is actually the overlap thats making the biggest idle difference...If i close overlap, idle quality quickly comes back...if i open it, it goes crazy...but if i find an overlap that idles ok, then start advancing or retarding both in equal measures...idle doesn't change...the engine and factory computers don't seem to care where the intake cam is exactly (many DOHC engines are extremely sensitive to that, where as ours, with stock computers at least...doesn't seem to matter for idle all that much)...its just the overlap that guts idle vacuum to the point where it lumps like a harley...this is strictly an assessment of idle though, i have no clue what happens to over all power...its just making the stated twiggy overlap numbers seem way off...

In either case...this has to be a situation of false information...somewhere...If my JDM cam set up i had in the car before had 10.5 degrees of overlap at .050" (I had a FS-ZE intake cam, and a mazdaspeed exhaust cam from Corksport...purchased in 2003...that was all the info i ever got)...and i put the NA twiggy cams in with built in '12' degrees at .050"...i can buy that...but if Mazda had some set up that had 17.5 degrees at .050 before...thats out of control...i'm pretty certain that if i would open overlap to that with my gears right now...it wouldn't even start...I know there is more to it than that, but given the amount of confusion surrounding the twiggy's specs...and using Occam's Razor, we're just missing some very small detail that will bring this all together...Andrew himself posted overlap numbers at the same lift that were off by nearly 2 degrees, back to back in the GB thread haha...

So its starting to look like there are 2 outcomes...either A) everything we've seen posted about factory spec cams is at some irrelevant lift, like .006" or something...not an unlikely possibility...Mazda has always had info like that very restricted and in some ways misleading (i.e. BHP measurements for the RX-8)...and i've yet to see numbers from anyone that actually measured them themselves...

or B)...Posted info on the NA twiggy's is either incorrect, or at some lift value higher than .050"...also likely, as the posted info is laced with contradiction in some very key areas...

so who knows haha...but iti'll be interesting to figure out soon. 11 years and i never once came across this 'unrevised' exhaust cam, dude...you learn something every day.

 

[Installshield 2]

Alright, drinking and bored...and waiting for my gf to get home from work with some food haha...but i think i've cracked the Twiggy numbers, so all that is up in the air now is the measurements posted for the various factory cam sets...I know this isn't really relevant to the build thread or anything, but its something to BS about in the mean time.

i'm deriving these numbers for Andrew's original posts about the NA twiggy's having 11.36 degrees of overlap...and the FI twiggy's having next to zero degrees overlap...and with a handful of information on the FI twiggys i've dug up...

NA twiggy lobe separation angle is 101.8 degrees, with a .050" exhaust closing event at 6.59 degrees ATDC...and a .050" intake opening event at 4.77 degrees BTDC...

so therefor...adding those two figures together illustrates the time in crank degrees of which they're both open:

11.36 crank degrees of overlap at .050"

NA twiggy intake duration at .050": 221.97 crank degrees
NA twiggy exhaust duration at .050": 231.17 crank degrees

the 11.36 degree overlap figure was at least posted by the creator...at some points he posted 10 degrees, others 12.7...but i'm pretty positive 11.36 @ .050" is an accurate number if the paper work i have is related to the cams in my engine...

So if we can find that Mazda actually made a cam for an FS engine that was more aggressive than the twiggy exhaust numbers above...i'd be extremely surprised...its very likely the factory numbers are at less lift...

 

[Ice88]

Alright, drinking and bored...and waiting for my gf to get home from work with some food haha...but i think i've cracked the Twiggy numbers, so all that is up in the air now is the measurements posted for the various factory cam sets...I know this isn't really relevant to the build thread or anything, but its something to BS about in the mean time.

i'm deriving these numbers for Andrew's original posts about the NA twiggy's having 11.36 degrees of overlap...and the FI twiggy's having next to zero degrees overlap...and with a handful of information on the FI twiggys i've dug up...

NA twiggy lobe separation angle is 101.8 degrees, with a .050" exhaust closing event at 6.59 degrees ATDC...and a .050" intake opening event at 4.77 degrees BTDC...

so therefor...adding those two figures together illustrates the time in crank degrees of which they're both open:

11.36 crank degrees of overlap at .050"

NA twiggy intake duration at .050": 221.97 crank degrees
NA twiggy exhaust duration at .050": 231.17 crank degrees

the 11.36 degree overlap figure was at least posted by the creator...at some points he posted 10 degrees, others 12.7...but i'm pretty positive 11.36 @ .050" is an accurate number if the paper work i have is related to the cams in my engine...

So if we can find that Mazda actually made a cam for an FS engine that was more aggressive than the twiggy exhaust numbers above...i'd be extremely surprised...its very likely the factory numbers are at less lift...

Yah thats what I was thinking as well. To give some back log to the JDM Cams, the MSF cam came out in the Mazdaspeed Familia of which only 209 where ever made. They came out in Japan only and are rare as s*** now a days, i forget when (theman will be able to tell you) but they issued a recall (TSB?) which allowed customers whom owned the MSF to return there car and have the exhaust cam replaced for a downspecd item that would enable them to run properly in the japanese winters. Apparently theres no real way to tell which cars got these replacement cams as mazda didn't keep record IIRC.

One of my friends actually has a MSF engine (Unsure if the TSB cam or not though) Doesn't have anywhere near the idle awesomeness that Darryl has at 1100 rpm (i think thats what he idles at).

I can help you with the Corksport spec cam specs as they were posted rather recently here:
http://www.mazdas247.com/forum/show...e-Cam-thread&p=6038926&viewfull=1#post6038926

Congratulations you have may have had a copy of the infamous MSF Cam, it goes against what I've read else where (other threads state its teh TSB cam) but apparently thats from someone at CS so potentially more accurate?

 

[br289165]

To return to your original topic; Musn't the conditions for MBT occur not only at peak cylinder filling or VE, but where peak combustion pressure combines with the best leveraged crank angle (near 15 deg atdc)in order to make that peak torque,as the two pistons (on our engines) which are moving in the same direction,downward in this case, with opposite cylinders (cyl's 1,4 for example), as they function inversely ,(intake vs power)? Perhaps these variables could only change the MBT up or down based solely on the way the engine is tuned (MBT) .In this case it is only relative to the engines ability at any given time to make that MBT. I guess so long as there is combustion, no matter how efficient and well timed,or not, there will always be a MBT for a given engine at a given time. Perhaps, however,the same physical engine,without any dimensional changes, may not always be as torque capable as possible given other variables, such as igniton/valve timing adjustments, which obviously will have effects whether positive or negative on the performance of that engine. To restate; MBT is only relative to the tuning of that engine based on the conditions present during the running of that engine under a static tuning situation (no changes),otherwise MBT would be unbounded in a dynamic tuning session, limited only by that engine's mechanical capabilities.Just a thought. Sorry bout the run on.

 

[AusOrion]

I can help you with the Corksport spec cam specs as they were posted rather recently here:
http://www.mazdas247.com/forum/show...e-Cam-thread&p=6038926&viewfull=1#post6038926

Congratulations you have may have had a copy of the infamous MSF Cam, it goes against what I've read else where (other threads state its teh TSB cam) but apparently thats from someone at CS so potentially more accurate?

The specs given in that linked cam thread are for the MSF (pre-revision) cams