newimportowner

iTrader: (2)

I have been having on on going issue for some time. When car is at operating temperature, it does not want to idle.

I had narrowed it down to the IAC. Dealer wanted like $480 for one of these so I decided I would just keep my eyes open for one, and in the mean time, I drilled two small .125 holes through the head of plastic piston of the IAC and crossed drilled it so air would get through at idle. My IAC is stuck closed at all times.

It has been running like this for a year or so, and its been fine, it could use a third hole but it stopped stalling at idle.

I came across a new IAC for a reasonable price recently. I replaced it and noted that there was no movement of the piston when the key was turned on and off. I bolted it up and test drove. Once engine was at temperature again it began stalling at idle.

I was going through what else could be wrong in my head. I do have issues with my rear O2 sensor, could this be the real problem and not the IAC. could a faulty rear O2 cause the IAC not to work?

Thanks in advance for any assitance anyone can be.

-Bill

Raptord

iTrader: (10)

Rear o2 sensor is only used for emissions purposes AFAIK, so it's unlikely your rear o2 has anything to do with it.

thedru13

iTrader: (24)

Have you logged the car at all? Also did you adjust your BISS screw?

Unplug the IAC, unscrew it., Disconnect the negative battery term. Plug in the IAC let car sit for 10 mins. Then connect neg back up. Turn the key just to the on and don't start check to see if the IAC moves. Also you can check the volts on the IAC..

Did you check for boost leaks? Do you have a test pipe or are you catted?

rhd-jon

iTrader: (11)

Jeezus man there are so many threads on this issue it's crazy.
Some people have solved the issue some have'nt im still dealing
with my car doing the same as well after i had my clutch installed 2 months ago good luck man.

newimportowner

iTrader: (2)

No it hasnt been data logged for about 90K. it is running a test pipe, and it seems to hold boost just fine. its tuned @24PSI. I have not adjusted Base Idle Screw.....I reread what you posted, are you saying to unplug IAC, then turn out BISS? disconnet battery to reset ECU, then plug in IAC, let car sit a bit, then connect battery back up? or did I misread that?

thedru13

iTrader: (24)

Yah do everything but leave the biss alone that would be a seperate adjustment.

dastallion951

the iac and rear 02 only work with each other as inputs to the ecu thats it. The rear 02 only works with the stock ecu, as to show a different voltage to the ecu then your front 02 sensor and thats to show the cats working, if there reading the same either damaged cat or bad o2 it usually throws a p0420 cel code.Your iac on the other hand, why would u drill it?????, your best bet is to buy another iac valve, and once its installed take it to your tuner, so he can redo your iac part of the tune, the values might be off, thus why the new one isnt working well. Make sure before installing it use some eletrical contact cleaner, and clean the inside of the port the iac valve goes into, sometimes gunk can get in there and mess with it as well. If that all checks out and theres still issues, they might have to play with your idle tables to get it back inline. Any cel codes pop up at all since it started stalling?

rhd-jon

iTrader: (11)

You can find new IAC valve on amazon for about $190.00 if you like to get a new one.
I'll be waiting to my car goes to the shop to have some stuff installed and tune see if the mechanic can figure it out.

Raptord

iTrader: (10)

I have a used IAC I can sell you if you like, feel free to PM me if you're interested.

newimportowner

iTrader: (2)

I drilled it to allow some air through at Idle, because I didnt want to be raped by dealer for 500 bucks, and It worked and still is like a charm, but it could use a lil more air with a third hole. 2 holes in the face plus two cross drilled hole to connect to the back side of piston head so air slips by, It actually works so well I had to put it back in to run and now it runs fine again. I have a new IAC alreay got it for $160, but this one doesnt work either, and thats what got me to thinking there has to be something else wrong. the only other thing that does not fucntion as the owners book said is the rear O2...well its not there anymore either.

There are a lot of threads similar to this I agree, but none are ever quite the same. I am a little perplexed however I think this is a simple fix, but I dont know how the parts interoperate with eachother,

Thanks again guys if you have any other ideas. I am thinking now at 130K it may be time to re-data log and tune, and maybe upgrade a few other things as well.

-Bill

newimportowner

iTrader: (2)

ttt really wanting some
help here

HaVoC187

iTrader: (4)

A broken front O2 sensor can also cause idle issues, like it was the case on my car. Take of the spark plug cover, unplug the sensor connector and start the car. If it fixes your idle you need a new front O2.

Raptord

iTrader: (10)

How will unplugging his front o2 sensor fix his idle if the sensor is the problem?

thedru13

iTrader: (24)

Are you positive you don't have any vac/boost leak? Also what BOV do u have? Might be something leaking. My stock DV was leaking a bit caused my idle to react like yours.

newimportowner

iTrader: (2)

Its worth digging into I guess, but it hold full boost on gauge and HKS EVC6 both say the same and it pulls like a freight train, but with the miles it could have something somewhere I guess. I am running the stock MR DV.