Idle issue - Chapter 3

[SnakeyesTx]

Okay, so the IAC was replaced since it was belching oil out of the end that the hose that goes up to the intake elbow connects to, same problem as I had stated previously in the last two threads for those that have been following. Replaced just about all the vacuum lines in, around and under the intake (precautionary for most, but one or two really were in bad shape) and still had the same problem.

Now, just to re-introduce you all to my problem which a few others have said they had; Car seems to run okay in warmer weather (over 75-80*F) but a little sluggish compared to Milkboot's 525 (same year same model). In cold weather when coming to a stop or sitting at lights, idle goes completely bonkers, ass-end of the car rocks up and down, sometimes so bad the car lurches into the guy in front of me so I usually stop about 3/4" a car-length back just so I don't hit people now, CEL comes on giving o2 sensor code (which was recently replaced along with the relay). A couple of pedal pumps and the light turns off but car remains sluggish.

One thing I keep forgetting to mention, in colder weather, the car has a LOT more power. Acceleration is really good, throttle response is really good until I come to a stop and the light comes on the first time (if I catch 3 or 4 stop lights, I get the CEL and idle thing 3 or 4 times - then sluggish feeling).

This is only in colder weather (denser, cooler air) so I'm starting to suspect the Intake Air Temperature sensor. Stealer wants 53 dollars for it and I can't have one until Monday, BMA wants 44 for it. Suprisingly enough some local parts houses want over 60 bucks for it! > Has anyone found one a little cheaper? Also, has anyone tried changing one out without taking off the intake? (It points straight up into the rear of the intake with the plug facing down, seems pretty cramped in there) Does it sound like I'm on the right track and has anyone solved their similar problem replacing that?

[Ross]

Have you tried autohausaz? They're not too far either.
FCP Groton is another I use for hard parts. The local guys buy reboxed stuff from a wholesaler, too many middlemen.
Good luck on this one, keep us posted.

[SnakeyesTx]

Wow... 18.83 there!

[Ross]

I'll have a Heineken at the next fest.

[Ferret]

Interesting - the slugishness after it's done the idle bounce a few times could usually be attributed to the ECU crapping out and going into open loop control mode aka 'limp home.'

This is very weird indeed - have you tried swapping the MAF in out of a different car in case it's having a fit at the cold air?

Have you checked the rubber boot that goes between the MAF and the throttle body - sometimes it develops cracks in the flexi bits that you cant see, and can cause trouble when they contract.

If you're still having trouble, I'd pull the intake manifold and replace the rubber seals that sit in the bottom of it... a while back I had one of these go south on me, snapped and you almost couldnt see it, but damn you could feel it.

A la part 2:


I'd also consider changing parts 4 and 10, they're only going to be cheap from the dealer.

[Morgenster]

This is only in colder weather (denser, cooler air) so I'm starting to suspect the Intake Air Temperature sensor. Stealer wants 53 dollars for it and I can't have one until Monday, BMA wants 44 for it. Suprisingly enough some local parts houses want over 60 bucks for it! > Has anyone found one a little cheaper? Also, has anyone tried changing one out without taking off the intake? (It points straight up into the rear of the intake with the plug facing down, seems pretty cramped in there) Does it sound like I'm on the right track and has anyone solved their similar problem replacing that?

Odd that yours points up at the rear of the intake. Mine is horizontal and the plug is right nect to the throttle body. You're sure?
I used to have this issue and it went away with some liberal use of intake cleaner, a few resets and and a couple of long hard drives.
Oh and do the problems persist when the car is fully warmed up?

[SnakeyesTx]

Yeah, the diagrams all show it going in horizontally next to the TB like you described. I think it may have to do with my motor coming out of a 325 (a wrecked 325 with 60k miles donated its engine to my 5'er last year). Even after I'm up to operating temp it still misbehaves. As Ferret suggested, the intake O-ring gaskets were replaced (I forgot to mention that) and the elbow was replaced. Also I did switch MAF's with Milkboot's 5'er since we're the same year/make/model and it still wanted to launch. For 18 bucks at autohaus, it's worth a shot. Just hope I can reach it without having to take the intake off :x