Losing my mind with this car!

okay, update...

Re-gapped the plugs to .40 and the car does run smoother, and idle a little better, but these are all minor changes. Still has the 3k stumble...leading me to believe it's not the plugs. Messing with them does change how smooth the car runs, but not the hesitation.

My next option is to wait on my new 2.0 packs to come in, unless there is any other ideas. What gets me is that the problem is at a very specific RPM, which leads me to believe it is a sensor issue of some kind. Trying to figure out which one is the hassle. As soon as I get some more free time, the manifold is coming off and going to inspect the VTCS butterflies to see if that's the cause. Might just swap to the 626 mani I've been sitting on while it's out also.

Thanks for the help everyone, this is very frustrating! I'll try and keep this as updated as possible to help out anyone else with this issue.
 
Has the motor in your car ever been rebuilt? I know that on the FS-DE heads, the valve seals start going out at around 150k miles. And that could cause issues at specific RPM's (when enough fuel goes into the combustion chamber, the blow-by makes its way into the intake and mixes extra exhaust gasses with the intake air, and could cause it to stumble). 3k RPM may be the event horizon (causing the stumble) and then the ecu compensates after that (making the stumble "disappear"). Then when it goes back to idle, it has to re-compensate again causing the low RPM and roughness after getting on the throttle... and after a few seconds it corrects itself. But this only conjecture. Have you done a compression test on your cylinders? Do you ever blow smoke out of your exhaust when you first start your car?
 
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Have not done a compression test on it. But it has been rebuilt, did it myself about 1500 miles ago. Had a spun bearing and the rings were going out, so did a complete build on it. It ran fine until the recent decision to switch to the 1.8 coils.
 
KCKrogoth said:
.... It ran fine until the recent decision to switch to the 1.8 coils.
Click to expand...

That's the whole thing... Unless you disturbed something during the install then coils still seem to be blamed ???

There's something about our coils liking to misbehave under certain " load demands" ...

That rpm maybe very demanding ???
Then your ECU does it's thing to compensate...

Our engine is allowed to misfire below a certain threshold.

 
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Understood, however, it's not just a normal here and there missfire. It's steady all the time every time I pass into the 3k rpm range. This is definitely not a normal operation. I'm also beginning to wonder if it's just coincidence that this problem happened the same time I changed the packs and could be non-related...
 
Just another random idea... Plug wires??? I see you have tried 2 sets though?
Many years ago on my 91' Protg, and also again on a 92 Miata, I had a split spark plug boot. The spark would arc to the engine head and eng stumbled at a very defined RPM. Ran, revved up, and idled fine, but it failed at a certain RPM under load. I thought it was so many other different problems until I traced it back to a split spark plug boot insulator. Since the boot cannot be seen, it is difficult to see this failure happen live, unless you enjoy pulling live plug leads at night so you can see the arc, LOL... You could test for this by taping the plug boots with some electrical tape. But because it gets so hot inside the head/valve cover area, the electrical tape on the boot wont last very long, it is just used as diagnostic tool to see if is the problem...
grasping at straws...
 
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KCKrogoth said:
Have not done a compression test on it. But it has been rebuilt, did it myself about 1500 miles ago. Had a spun bearing and the rings were going out, so did a complete build on it. It ran fine until the recent decision to switch to the 1.8 coils.
Click to expand...

When you rebuilt the head, did you have it machined before installing valves, seals, retainers and springs? The reason I keep referring to the head is Im having some similar issues with my MSP. I know I have 2 cylinders (2 and 4)with leaky intake valves. My car smokes on start up...sometimes (depending what position the cams are when I shut it off). Around 3500 RPMs (when my turbo spools up past 6 or 7 psi) my a/f ratio goes way down then way up when my ecu tries to compensate for the exhaust gasses blowing by the intake valves back into the IM. Then when it goes back to idle, it stumbles at low RPM for a few secs then fixes itself. It sounds alot like your problem (minus the charge air, of course). Your problem has similar symptoms to a vacuum/compression leak...

An unrelated but somewhat related question; why switch to the 1.8 coils?
 
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KCKrogoth said:
... It's steady all the time every time I pass into the 3k rpm range....
Click to expand...

I do know that rpm is where our "power band" kicks in (unless you have the msp ecu or flash).

(I remember feeling it out on the highway... with the throttle held steady and slowly gaining speed, you could feel the car take off at that exact rpm)

So... It could make sense that the "coil load failure" wouldn't be a random, unpredictable event.

Then.. perhaps.. fouling of the cylinders and maybe injectors can occur due to the unburnt fuel carbonizing everywhere from the misfiring preventing your original setup from working again.

Either way, I think it's spark related. Plugs, wires, coils, and the wires and connectors leading to the coils... Maybe check your connectors and hose them down with your MAF spray...

Keep in mind that the gremlins that haunt our coils are the trickiest and most organized of all the gremlins that haunt our car.... they can morph from logical to illogical,.. intuitive to counterintuitive... they know when you're after them and take evasive action.
 
I'm pretty sure it's not a split spark plug wire, considering that I've gone through 2 brand new sets, and then reverted back to the old set with the same/similar results.

polaris said:
When you rebuilt the head, did you have it machined before installing valves, seals, retainers and springs? The reason I keep referring to the head is Im having some similar issues with my MSP. I know I have 2 cylinders (2 and 4)with leaky intake valves. My car smokes on start up...sometimes (depending what position the cams are when I shut it off). Around 3500 RPMs (when my turbo spools up past 6 or 7 psi) my a/f ratio goes way down then way up when my ecu tries to compensate for the exhaust gasses blowing by the intake valves back into the IM. Then when it goes back to idle, it stumbles at low RPM for a few secs then fixes itself. It sounds alot like your problem (minus the charge air, of course). Your problem has similar symptoms to a vacuum/compression leak...
Click to expand...

Yes, I had the block, head and crank machined and the whole 9 yards when I performed the rebuild. I also did the valve job myself and ensured it was all a tight fit. However, I have not tested the head or block after the build assuming it was all okay because it ran just fine until the coil swap. But, for the sake of eliminating problems, I do have a compression tester and a leak-down kit and will definitely do both tests. The car doesn't smoke during startup or while running and all the plugs are really clean and lack oil or fuel smell/visual issues.

polaris said:
An unrelated but somewhat related question; why switch to the 1.8 coils?
Click to expand...

I wanted to do it for more of a visual than anything. I decided that it looked better than the stock setup, and also thought that the packs on the car were getting fairly old and could probably use a replacement. From what I have read, they 1.8 setup was supposedly better ignition system (for trivial reasons really). Who would have thought it would be the future bane of my Pro5's existence...lol

A few other ideas that I tossed around with one of my fellow car peoples I know at work today that I might also look into, and I have had in the back of my mind for a while since the issue started, is a possible timing problem. Reason I think this is I feel like the engine lacks general power throughout the power band as if it's off a tooth or two or the belt slipped. That side of the engine is coated in oil pretty good because of the use of cheap seals (don't use DNJ crap!) when I rebuilt it. My guess is that the belt is soaked in oil and slid. I really need to pull the engine again and replace the seals with the new Fel-Pro stuff I purchase for it a while back, but I want it running right before I tear it out again so I'm not chasing ghosts when it goes back in again...Not that I'm not doing that now however...

I haven't done much of the larger issue troubleshooting like tearing the engine apart to check problems like timing because it has been too damn cold outside to want to deal with it for a long period and lack of a garage really sucks.
 
pcb said:
Keep in mind that the gremlins that haunt our coils are the trickiest and most organized of all the gremlins that haunt our car.... they can morph from logical to illogical,.. intuitive to counterintuitive... they know when you're after them and take evasive action.
Click to expand...

HAHA...Love this! I feel like you are probably correct, and I want to do the new packs before I more any deeper into the issue. I'm basically on a halt until the new packs come in this weekend. If it doesn't fix it, then major tear apart and testing will happen...Compression test, leak down test, tear off the intake mani to check VTCS, take apart side of engine to check timing, etc...
 
It could still be as simple as dirty (not clogged or stuck) injectors.




If this is what's happening then your NOID test probably wouldn't pick it up. (I don't know exactly what that is... I thought it was the little red dude that works for Domino's Pizza.)

That combined with a "weak" coil from the 1.8 (perhaps) could have combined to push it past the threshold and keep it there. (dirt)



I am a firm believer in seafoam... The last time I had my tailpipe sniffed for emissions (4 years ago... they use the OBDII port now) the guy had to do the test twice because his machine couldn't get a reading... My car polluted less than new car specs!!

If you put it in with your New oil every time it will keep your sludge down and those damn oil rings free and moving.

If you are not burning Any oil then there is no gunk in the exhaust to condense on our fuss ass EGR's and plant a ghost there.

I still have my original EGR on my car and have never had a problem with it... and I live in Canada where the redesigned EGR was built for.

I put a shot of it in with my gas every fill up and feed it up the brake booster every time I have the slightest stumble at idle.

It's just so much easier to keep it clean than to try to fix it after it's got clogged arteries, lungs and may have internal bleeding.
 
Funny thing is; in the end it'll prolly be something obvious and simple.

...you try tightening the negative battery terminal yet?
 
KCKrogoth said:
I'm pretty sure it's not a split spark plug wire, considering that I've gone through 2 brand new sets, and then reverted back to the old set with the same/similar results.



Yes, I had the block, head and crank machined and the whole 9 yards when I performed the rebuild. I also did the valve job myself and ensured it was all a tight fit. However, I have not tested the head or block after the build assuming it was all okay because it ran just fine until the coil swap. But, for the sake of eliminating problems, I do have a compression tester and a leak-down kit and will definitely do both tests. The car doesn't smoke during startup or while running and all the plugs are really clean and lack oil or fuel smell/visual issues.



I wanted to do it for more of a visual than anything. I decided that it looked better than the stock setup, and also thought that the packs on the car were getting fairly old and could probably use a replacement. From what I have read, they 1.8 setup was supposedly better ignition system (for trivial reasons really). Who would have thought it would be the future bane of my Pro5's existence...lol

A few other ideas that I tossed around with one of my fellow car peoples I know at work today that I might also look into, and I have had in the back of my mind for a while since the issue started, is a possible timing problem. Reason I think this is I feel like the engine lacks general power throughout the power band as if it's off a tooth or two or the belt slipped. That side of the engine is coated in oil pretty good because of the use of cheap seals (don't use DNJ crap!) when I rebuilt it. My guess is that the belt is soaked in oil and slid. I really need to pull the engine again and replace the seals with the new Fel-Pro stuff I purchase for it a while back, but I want it running right before I tear it out again so I'm not chasing ghosts when it goes back in again...Not that I'm not doing that now however...

I haven't done much of the larger issue troubleshooting like tearing the engine apart to check problems like timing because it has been too damn cold outside to want to deal with it for a long period and lack of a garage really sucks.
Click to expand...

I would think that a slipped timing belt would set a cam/crank correlation code, but you never know.

Do a running compression test to check for valve problems.. At idle your readings should be 50% of spec, a WOT blip should be around 80% of spec. High readings mean an exhaust valve problem, low readings indicate an intake valve problem.
 
pcb said:
If this is what's happening then your NOID test probably wouldn't pick it up. (I don't know exactly what that is... I thought it was the little red dude that works for Domino's Pizza.)
Click to expand...

LOL...Noids are what you use to check injector pulse signal from the harness. It's a little set of lights that have prongs on them. You plug them into the harness while the car is running and they flash showing pulse signal. Doesn't check the injector itself, just the ECU signal. Injectors could possibly be dirty, not ruling that out, but i find it hard pressed being I talked to the local speedshop here that does injector cleaning among other things, and he said that it's actually pretty rare to have dirty injectors now a days due to the extreme amount of Ethanol in modern gasoline. It acts as a cleaner and keeps the amount of varnishing down. Not saying that there couldn't be a small piece of dirt in there, but when I pulled the fuel pump and changed the filter housing, and screen, the tank was immaculately clean inside...leading to be that it's highly unlikely. I will however run some seafoam through the systems, not against it, but haven't really had any results from it in the past. Either way, couldn't hurt.

polaris said:
Funny thing is; in the end it'll prolly be something obvious and simple.

...you try tightening the negative battery terminal yet?
Click to expand...

This is most likely the case for sure, almost always it something easy and simple that gets over looked. The terminal is tight, yes...lol

pcb said:
This... With your smart phone and the torque app... $10 online.
Click to expand...

Never seen that, might have to get something similar or just a better diagnostics scanner, being that I work on my vehicles a lot and could probably use it. Too bad it wouldn't work on my Sil80, OBD I...
 
KCKrogoth said:
LOL...Noids are what you use to check injector pulse signal from the harness. It's a little set of lights that have prongs on them. You plug them into the harness while the car is running and they flash showing pulse signal. Doesn't check the injector itself, just the ECU signal. Injectors could possibly be dirty, not ruling that out, but i find it hard pressed being I talked to the local speedshop here that does injector cleaning among other things, and he said that it's actually pretty rare to have dirty injectors now a days due to the extreme amount of Ethanol in modern gasoline. It acts as a cleaner and keeps the amount of varnishing down. Not saying that there couldn't be a small piece of dirt in there, but when I pulled the fuel pump and changed the filter housing, and screen, the tank was immaculately clean inside...leading to be that it's highly unlikely. I will however run some seafoam through the systems, not against it, but haven't really had any results from it in the past. Either way, couldn't hurt.



This is most likely the case for sure, almost always it something easy and simple that gets over looked. The terminal is tight, yes...lol



Never seen that, might have to get something similar or just a better diagnostics scanner, being that I work on my vehicles a lot and could probably use it. Too bad it wouldn't work on my Sil80, OBD I...
Click to expand...

I am really pleased with the Torque Pro app and Vgate ELM327 adapter that I have.

I can do everything that a $500+ Snap On Ethos can on most vehicles, and I like the interface more.

You'll need an Android device with Bluetooth.
 
MrGiggles said:
I would think that a slipped timing belt would set a cam/crank correlation code, but you never know.
Click to expand...

My theory on the no Codes thing is this however...The car has a dead battery from me letting it sit for so long after giving up on it for a while, and I have to jump it every time I want to run the engine. I think that I don't have it running/driving around enough to throw any codes, and the ECU just gets reset every time I shut it off. Really should replace that battery, but they are so damn expensive and need to wait on some funds first...Stupid cars and their costly maintenance (confused)
 
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