Idle Issues

[esnave09]

I've been having a couple issues with my P5 relating to idle, and I feel like I know the issue (idle air control valve or EGR), but I just wanna make sure before I start taking things apart.

First issue: I've been having this issue very rarely, but when it happens it is annoying. Occasionally my P5 will start up just fine, and if I leave in the clutch or let it idle it will die right away, and it repeats for a minute or so if I'm not careful. It's a very odd issue, because it mostly happens after I've been driving he car for 3+ hours, happens for a minute or so, and then stops. I did notice that my car kinda stumbles on those starts, but no other clues. I've been trying to narrow it down because I can't notice any real consistency in when it happens. The only common factor I've noticed is that it doesn't happen in the winter (so helpful, right?). My car idles at 500 after warming up (sometimes a little lower maneuvering in parking lots) and gets a little shaky around that point from stiff motor mounts (just replaced them last month). Any ideas besides what I mentioned above?

The second issue is more a question as to whether or not this is normal. When I hold my clutch in or put the tranny in neutral when coming to a stop, I've noticed that my engine idles at 750 just fine. However, when I do stop, the idle drops to about 500. Is that what's supposed to happen (ECU thing maybe?).

I posted the same thing on ClubProtege, but figured I'd try and see what you guys have to say.

 

[icantshift]

Maybe start with a good MAF sensor cleaning, that helped my rough idle.

 

[kms1990]

+1 on maf cleaning (i do it any time i clean k and n filter i have or when i clean engine bay) check your intake hose for rips replace the $3 pcv valve and seafoam it through the brake booster. ( i do this every oil change to keep it clean 1/3 in brake booster vacuum hose 2/3 in gas as i do not put it in with my oil.)when cleaning the maf go ahead and clean the intake and throttle body with some throttle body cleaner as it cant hurt. if none of the above works its time to dig deeper, you may have a loose or broken hose causing an air leak it maybe a very clogged (even more so then seafoam can fix) or broken egr valve it maybe spark plug/wire or coil time. just giving suggestions on things to do/check for when having this issue.

without a check engine light code its hard to narrow it down if it were throwing an egr code or a lean bank one it would be very easy to point you in the right direction.

 

[The_big_dill]

IAC from what I can tell. Try turning on your A/C when Idling, what happens?

 

[esnave09]

Yeah I've checked for codes before when this has happened and haven't gotten anything. Not even anything getting ready to turn on the CEL.
I just replaced the spark plugs and coils last summer (about 18k miles?) as well as Seafoamed, and my intake is dinged up but not leaking (eBay intake) by the brake booster. I am overdue for an oil change, so I'll probably Seafoam it again before I get one. How do I clean the MAF? Do I just spray it out with throttle body cleaner or wipe it? And will Carb cleaner work for those?

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[The_big_dill]

Yeah I've checked for codes before when this has happened and haven't gotten anything. Not even anything getting ready to turn on the CEL.
I just replaced the spark plugs and coils last summer (about 18k miles?) as week as Seafoamed, and my intake is dinged up but not leaking (eBay intake) by the brake booster. I am overdue for an oil change, so I'll Seafoam it again before I get one. How do I clean the MAF? Do I just spray it out with throttle body cleaner or wipe it? And will Carb cleaner work for those?

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Do not use carb cleaner... There is special MAF safe cleaners, will say so on the bottle. Look it up, a video will explain how to clean it better than our words.

Furthermore, I would check EGR and IAC before you do MAF.

 

[kms1990]

as above use only MAF cleaner on the maf do not allow any other cleaner to contact it. clean up your throttle body and iac really well and see if that helps, you may have some build up on the iac opening.

 

[icantshift]

I also ran the ebay intake with the cheapo filter included with it. I'm pretty sure it wasn't filtering absolutely everything and gunking up my MAF causing my idle issues. I would get a proper K&N on it as soon as you can.

 

[esnave09]

trust me, I'm getting rid of the eBay intake altogether. I have a Weapon*R intake I'm gonna put in soon (probs when I clean my EGR). So you guys are saying I shouldn't use the carb cleaner on the EGR and IACV either, or just the MAF?

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[The_big_dill]

Just the MAF, but it is preferable to get TB cleaner for everything else.

But I suggest you turn on your A/C at idle and tell us what you experience with the revs, that is one of the biggest loads you can place on your engine and if your IAC isn't working properly, your revs will most likely drop too low and your engine will stall.

 

[icantshift]

trust me, I'm getting rid of the eBay intake altogether. I have a Weapon*R intake I'm gonna put in soon (probs when I clean my EGR). So you guys are saying I shouldn't use the carb cleaner on the EGR and IACV either, or just the MAF?

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Use only MAF specific cleaner on the maf. As for the IACV and EGR people tend to use whatever they think works best.

 

[kms1990]

Use only MAF specific cleaner on the maf. As for the IACV and EGR people tend to use whatever they think works best.

yes you can use carb cleaner or intake cleaner on iac on egr if you completely take it off then you can use brake clean or throttlebody cleaner

 

[esnave09]

Okay awesome. I'll probably start working on those today since my car is immobile til tomorrow anyways.

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[kms1990]

remember if you remove egr valve get a ride to the local parts store and get a new gasket to put it back on with, dont want to throw codes!