Dipping Idle problem?

[Ryoga28]

For the past two or three days, I've noticed that my car would dip to 500 rpms when coasting to neutral. It doesn't matter what the rpm is (blow off or not). I'm currently running a dual setup (stock bpv, greddy type s with three threads exposed). Never had this problem before until recently.

Yesterday, I changed my spark plugs and did a seafoam injector cleaning and noticed white smoke coming from the exhaust manifold area...This never happened to me before.

Possible problems I can think of at this time is a leaky vacuum hose, cracked manifold, or bad gasket between turbo and s pipe (recently had my mechanic install the GHL dp).

Has anyone else encounter this problem before? any solutions?

[terbow]

I have dipping idle too. Im recirculating. Ive had it for so long. Even with stock stuff. Perhaps it was post GHL tho, i cant remember that far back.

I havent solved it yet. In fact i Havent had time to even look at it. :(

[MSP #167]

thread jack.....but how many miles do you have on your car that you performed seafoam on it?

[Devilspawn]

subscribes...

I had this happen to me this weekend on a 2 hour trip, and my car is stock...

[Ryoga28]

thread jack.....but how many miles do you have on your car that you performed seafoam on it?
about 16k. I use seafoam about every 3k.

[Paul]

mine does this

[CasopoliS]

I also get the dips.
Where do you put the seafoam? Just put a vac hose in the can? I bought the stuff a while ago but never cleaned out the top end. Thanks.

[Ryoga28]

I also get the dips.
Where do you put the seafoam? Just put a vac hose in the can? I bought the stuff a while ago but never cleaned out the top end. Thanks.

I attached a hose extender to the vac hose that goes to the pcv valve. It works very well.

[Ryoga28]

Cap-did you get the dips with the blow through maf setup? or did you notice the dips after you install the ghl pipe?

[Paul]

actually mine doesn't do this since i moved my vacuum lines to my booster line & have the T fitting from the wastegate to the bottom nipple on the greddy.
only downside is 10psi.

[Ryoga28]

actually mine doesn't do this since i moved my vacuum lines to my booster line & have the T fitting from the wastegate to the bottom nipple on the greddy.
only downside is 10psi.

You still haven't fixed the 10psi?

[Paul]

^^nope not yet. but my idle doesn't dip as much as it did. you should try my setup, 10psi is fun

[Hughes412]

I don't think it's a turbo related problem. It seems more of a mazda problem. I get this same thing. It got to the point were it would almost die. I put in the MP3 ECU and while it still dips it doesn't do it as bad, you almost can't feel it. I noticed this started happening after I put in the CAI. I wonder if the vac-line to the valve cover is to short?

[Spooled]

Is there a possibility that the hotwire MAF that Mazda uses could be the cause? I would like to see a spreadsheet of everyone on the forum with these columns:

Member name
Car
Idle dip problem (yes/no)
Stock intercooler (yes/no)
Stock pipes (yes/no)
MAF or MAP
Relocated MAF (yes/no)
Spark plugs
Intake setup
BPV, BOV, or dual
Stock ECU (yes/no)
VTCS removed (yes/no)
Stock exhaust manifold (yes/no)
Mileage

The reason I left things out like exhaust and such is because I have aftermarket exhaust and it didn't fix anything.

If someone has time, it would be nice to have a MySQL DB table setup and a questionnaire page hosted that we could link to and collect that info. That way we could see patterns easily.

What do we know about it so far:
1. It only happens at idle. Touching the gas slightly stops the problem.
2. It only happens when the engine is warmed up.

What we need to know:
1. Do people with the VTCS removed have the issue?
2. Do people with hard pipes have the issue?
3. Does a better intercooler stop the problem (super hot air at idle???)
4. Does relocating the MAF help? Maybe the MAF gets a bad reading at idle because of inconsitant air movement at idle.
5. Who are the people that DON'T have the idle dip problem? If we figure that out, we can see what they have in common.

When the car is idling, the ECU is shooting for stoich. If it's getting a bad reading from the O2 sensor, that could cause it to fluxuate. For instance, maybe the uber rich environment is killing the O2 sensor and making it difficult to get readings at low exhaust speeds. I'd like to see if starting with a fresh O2 sensor after tuning the engine fixes the issue.


Just a bunch of rambling to hopefully trigger an idea.

[Hughes412]

I wouldn't think it's the o2 because mine did this with the stock exhaust (with the wagner shory header). What would be nice to know is how many people that have this problem have an aftermarket air intake system.

[CasopoliS]

Cap-did you get the dips with the blow through maf setup? or did you notice the dips after you install the ghl pipe?

pretty much occured every once and a while on every setup. Mostly with the AC on. Right now it is idling good.... so far. This morning my ECU was still learning from my late FMIC install... and it was idling at 3.5k with a cold engine!

[msp35]

I too notice the idle dipping @ times. Whether it's coastig or just sitting @ idle. it'll idle anywhere from 500 to 1200 rpms. Sometimes it'll try to stall but catch itself and correct it. Only running a GHL DP, K&N drop in and 10psi, colder plugs. It did this even when I was all stock though.....I say it's just part of mazda's SHITTY tuning.

[Spooled]

Mine did it with stock intake and stock exhaust, and also with 3" DP back exahaust and a cone filter. Is there anyone that does NOT have this issue? That would help a ton.

[apocman]

you may want to take the heatshield off of your exhuast manifold and look for a crack. T-99 and a I think a few others have had cracked manifolds, as a matter of fact T-99 is suppose to get his replaced this week at the dealer.

[Spooled]

Mine had a bolt backed almost all the way out a while back. I was actually looking for cracks at the time because it sounded like an exhaust leak. I still get the idle dip after fixing that.

[Paul]

heh, ignore my first post. went for a drive and at ever stop the idle dipped.
usually stays between 700-800. it then usually drops to about 450ish rpm's.
on a cold engine when i first left the parking lot it was idling at 1100 then dropped to 1000 rpms and stayed there.
weird

[hoindawall]

on my crappy a/f guage, it reads almost buried lean when the idle starts to dip. and i noticed it usually happens when the a/c fan turns OFF.

[jflo]

clean the EGR valve ? i'm doing the how-to clean it tomorrow by 122 vega. it might help

[Mazdaspeed989]

I just got hit today...i don't know if it has to do with the accident or not but my rps drop and my car almost stalls then revs itself up to about 2 grand then back down to about 1000...after driving it around it sits at about 600 when in neutral. I hadn't noticed that until today so i'm not sure if it is b/c of my recently installed AFC or the accident. i have a 2.4" dp back exhaust, intake, Airflow Logistics AFC.

[Paul]

i started her up tonight and it was cooler out than usual and i noticed the exhaust was loud. it was idling at 1500rpm. it's never been that high. drove out of the parking lot and going down the bump she was idling at the line above 0. what's that like 100-200rpms?
every time i stopped before i hit the express way she was dropping down to that line.
honestly i'm starting to think that possibly it could be the ECU flash from mazda.
who has the flash and has dipping problems? and who doesn't have the flash and has dipping problems?

[ChopstickHero]

mine dips occasionally. idle is about 600 consistent, but sometimes if i'm at a stoplight it dips down to 300 and jumps back to normal. i'm in netural and not stepping on the clutch. i believe my car is flashed though (i bought it used but never verified this).

[hoindawall]

mine dips occasionally. idle is about 600 consistent, but sometimes if i'm at a stoplight it dips down to 300 and jumps back to normal. i'm in netural and not stepping on the clutch. i believe my car is flashed though (i bought it used but never verified this).

pretty much what i have but i'm not flashed.

[Brian MP5T]

Normally only when the car is cold...

[Spooled]

Ok, I slapped my stock intake back on and I haven't had the idle dip since then. One thing that I was thinking is that maybe the stock air box is smoothing the air oumore than we think, and it's bufferin the MAF from fluxuations (like my radiator fan kicking on and blowing hot air at the cone filter). I'd bet that's what was going on (at least with my car). Now I'm starting to doubt that I had the dip when I had my stock air box on before.

I definitely notice a longer spool time now, and it's amazing how much quieter it is that a cone filter. Time to find a cheap CAI.

[icespeed]

I have stock pipes and, a cheap apc(???) air filter. I have had this idle problem since the day I switched out the stock air box. To test it, I kept switching between the filter and air box. Big difference. I then purchased one of the intake filter heat shields. I haven't had the problem but maybe two or three times over the past 5-6 months. I think it has to do with the radiator fan (not a/c fan) and the MAF. It seems that the MAF picks up on the flowing air from the fan and the ecu adjusts appropriately. I must say that heat sheild (once again, apc????) has helped this problem out greatly and it is much better than the stock box. The only times I've noticed the dip, since putting the air filter heat shield on, is when it is Extremely humid or Extremely hot out down here.

Spooled:
Member name: Icespeed
Car: 2003.5 Sunlight Silver MSP
Idle dip problem: used to frequently, not really anymore
Stock intercooler: yes
Stock pipes: yes
MAF
Relocated MAF: no
Spark plugs: stock
Intake setup: air filter mounted to stock placed MAF
BPV, BOV, or dual: stock BPV
Stock ECU: yes
VTCS removed: don't know what that is, so probably no
Stock exhaust manifold: yes
Mileage: 33,000 of which 26,000 have been at 10-12 psi

[JBreed]

dipping idle as well, not with stock air box though. I have a Injen CAI

[Spooled]

So it's starting to look more and more like the filter placement is the problem. How about people with CAIs? The filter is in the wheel well and shouldn't have issues when the radiator fans kick on. The longer pipe should smooth the flow out before the MAF, too. People that reposition the MAF shouldn't have problems, either, if this is the case.

[Brian MP5T]

When I clean my K&N it goes away.

[fattyboombatty]

my car idles consistently around 400-500 rpms and it nevver happened untilll i started getting 93 gas, i used to get like 89-90 until i started reading what everyone started saying here and thats exactly when it started

that day when super in my car, it was idling rough and the idle wasnt consistent and then it just stuck around 400-500 ever since but i do keep getting super

[tallrd]

*gets up on soapbox*

I have idle dipping.
I have random rough idle problems.
I get random backfiring.
My car sometimes won't go into second gear b/c Mazda syncro's are shit.
My stock subwoofer was shit.
My entire front end squeeks like crazy over large bumps in the cold.
Besides that, it's great (jerkit)

I think the engineers at Mazda didn't want these cars to be tuned b/c for every one thing I've done to this car it's had 2 things f up as a result. Very frustrating, and if it didn't handle and look so damn good I'd have sold it.

This is my least productive post ever. thank you.

*gets off soapbox...gives thread back...drives to bridge...kills self*

[fattyboombatty]

I am going to do an experiment and start putting 87-89 gas back into my car for a couple of weeks and see if my idle goes back up, if not atleast i have an excuse to buy some cheaper gas and save some money (moon) (boom02)

[Paul]

i think i may go back to using mobile instead of shell v power and see if that helps any

[Spooled]

87 octane in a turbocharged car is asking for trouble.

[Paul]

i never said 87. mobil has 93

[terbow]

hes talkin about fattybommbatty. pay attention! ;)

[Ryoga28]

Could it be the oxygen sensor acting up? My car is in the shop for repeated blowing the fuse that powers the ecu, fans, other critical functions. The problem may be a faulty primary oxygen sensor.

[fattyboombatty]

87 octane in a turbocharged car is asking for trouble.

youre right i was just trying it out to see what would happen but nothing yet, im gonna stick with 89 for a couple more weeks and see if anythingchanges it might have gone up like 100 rpms at idle since i went back to 87/89

[Ryoga28]

Fattyboombatty-Please use 91 or above octane.

[peepsalot]

Could it be the oxygen sensor acting up? My car is in the shop for repeated blowing the fuse that powers the ecu, fans, other critical functions. The problem may be a faulty primary oxygen sensor.
When I blew my ECU fuse, it was due to a loose ground wire.

[MSP #167]

Fattyboombatty-Please use 91 or above octane.

(werd)

[Ryoga28]

When I blew my ECU fuse, it was due to a loose ground wire.

I hope I just didn't waste $118 for a primary O2 sensor (Oem plug in) and plus labor and diagnosis. Sigh

[Brian MP5T]

Dirty Air Filter Will Do This As Well.

[terbow]

i have a brand new air filter, but i also noticed sam said my car should be idleing at 14.9 with his map but it doesnt stay still it jumps from 14.0 to 16.5 on the WB so im wondering if my primary 02 is to blame. i also have a mani leak i need to tend to .. that could be it. well im guessing its leaking cause its kinda loud near the mani.

[Brian MP5T]

Ok, Just that is what fixed it for me...

[terbow]

no i know, i was lookin for some help haha, im sure it could be a bunch a diff reasons for all of us.

[doggman]

Member name David
Car 03 black msp
Idle dip problem (yes/no)
Stock intercooler (yes/no)
Stock pipes (yes/no)
MAF or MAP
Relocated MAF (yes/no)
Spark plugs ngk one step colder
Intake setup injen cai
BPV (stock), BOV, or dual
Stock ECU (yes (flashed)/no)
VTCS removed (yes/no) but dont know what this is
Stock exhaust manifold (yes/no)
Mileage 25000

-dave

[genius]

I used to have it as well. But after I did my last upgrade with the SU SMIC, I used the T's and hoses that Cullen included in the kit and not only did my vac go from -20 to -22, but the rough idle settled down a little.

Then I took my one step colder plugs that was in there out and they were all sooty as hell. I went to the store and bought the stock plugs and the rough idle is completely gone.

Go figure!

[Katya4me]

There was a thread on this before, same section. I think it affects all the 3rd gens: http://www.msprotege.com/forum/showthread.php?t=96700&highlight=idle

[chowhoundMSP]

This used to happen to me all the time when i was stock, but now i no longer experience it at all. The hard part for me would be narrowing down WHEN it stopped. Ill have to think about it for a while.

[Spooled]

Mine stopped doing it when I took the cone filter off and put the stock air box back on. Now I have an Injen CAI on, but it still hasn't been dipping.