Here's what happens : I'm driving along (fast or slow) and see a stop sign or stop light approaching. I get close enough to the stopping point and I put it in neutral and coast to a stop. As soon as I put it in neutral, the idle speed goes to 2000rpm until I slow down to like 1-2MPH and stop. When I do get to that 1 or 2MPH the idle goes down to where its supposed to be around 800-1000rpm.

this typically seems to happen when I drive in the cold like it has been at night and in the mornings... like less then 45* out. I drove it to work this morning and it was 38* and it did it every time I came to a stop. Then coming home after work, the temperature was 63* and it did not have this idle problem at all.

SO, ANY IDEAS???

 

Clean the throttle body, making sure you clean the IAC valve very well.

 

what other ideas, if the the throttle body it spotless and a brand new iac

 

Vac leak and/or air leak in the intake post-MAF.

 

I'm pretty sure its not an intake leak. Its the orignal stock IAC from 1996 and I'm sure theres some oil residue from the pcv/fresh air tubes. I didn't even think about the oil. Does the IAC have a typical lifespan? Or is it something that you typically should have to clean once in a while? I think I have a catch can laying around somewhere, may have to put that in if the oil is becoming a problem. thanks for the suggestions.

 

IAC, to me, is a normal wear item, and should be held as high as a priority as a tune-up.

Its perfectly normal for oil to get back to the throttle body. A catch can isn't going to help out a whole lot unless you have changed up your PVC system and are blowing oil back up into the intake.

 

pcv setup is like stock. Although, I do seem to get some oil back up to the throttle body. Not sure where the thresh hold would be for how much is okay. Back on the original motor, I tried using a breather setup and it would get very oil soaked to the point oil was dripping onto the valve cover from the breather.

I've been changing out sensors one by one since I got the new motor and haven't gotten the IAC yet. I might as well go ahead and get that.

 

hey did you rear my threads i have the EXACT SAME PROBLEM!!! pm me if you find out

http://www.camaroz28.com/forums/show...57#post5122257


i just went into more detail...try shifting clower an see if it reve between gears also..mine does...

i have no vac leaks....iac counts are perfect....vacume at idle is great fuel pressure is great no codes....what i hear is that the stock iac tables are like that and you need to have them modified....

let me ask you this when your car is perfectly warm...all the way and you come to a stop does it still do it?

 

have the exact same problem getting a lil fustrated with it

 

sounds like IAC..mine did something similar and I changed out the IAC and the problem went away

 

There is also a table in the computer that increases the idle air counts based on road speed so that the car does not abruptly slow then you let off the throttle. This will make the idle speed higher based on if, & how fast you are moving. It should read around 1500rpm when you throw it in neutral at say 40mph. This is normal.

 

is there any way you can delete that table when tuning?

 

i replaced my iac with 2 differant ones one i know works perfectly...all of them checked ok with shbox site
bryan at pcm4less told me that the iac tables need to be cut almost in half to fix it...but i assumed it something wrong with my car...

 

are you running a cooler t-stat? the car could be having trouble warming up. I had it happen in the winter a few times.

 

also wondering if it can be removed?? as mine does it too until you come to a stop then it idles where it should

 

stock stat for me

 

160* stat here. The car does it randomly but seems to do it more often in the cold, on a cold start up. It did do it yesterday when the temp outside was around 65'ish. I got frustrated with it yesterday and shut the car off at a stop light and restarted it and that somehow fixed the problem for the rest of that drive. I killed my PCM today so, might be a while till I get any further with this little issue.

 

hmm really? mine simply has to be warmed up...mine does it ALMOST every time its cold....

 

Have you tried cleaning the EGR valve?

Wonder if the air pump has anything to do with this.

 

check the TPS voltage on cold idle.