So I port and polished my throttle body which included filling the IAC and vent ports and drilling them back out. I also removed and cleaned my injectors, tightened down my intake manifold bolts a bit as they felt loose, remove my air box baffles and fins and cleaned all the sensors including the EGR.

Now my idle fluctuated between 800 and 1200 RPM when stopped and it revs around 1500 RPM when rolling until I come to a complete stop, then it starts to fluctuate again.

I fixed a leak at the IAC port but that's the only one I could find, I also removed a vacuum hose to see if there would be a difference and there was no difference. So would a leak really explain my erratic idle?
I've done a PCM and IAC relearn, cleaned it, tested it, etc....
Fuel trims showing -10 to -15 on both banks.

Any ideas???

 

did you clean the maf, if so with what and how.

 

Dam, you might have me here. I used carb cleaner by spraying it from a distance...
I also de-screened my MAF for some stupid reason...
My MAF readings are about 9 g/s at idle.

 

yep you want to use maf cleaner, anything else can screw it up. not really up on the numbers but i think 9 is high.

 

I did investigate the wiring and vacuum lines better just now and found a few things! All the sensors seem to be reading so my guess is my wiring is fine.
My IAC is showing at 0 for some reason on my scanner.... And no reading for my TPS unless its a reading from the intake manifold.

Thanks, I'll keep that in mind haha


The PCV plumbing at the back is very cracked and soft which is probably creating a vacuum leak. I'll try replacing it soon.

Another leak I found: There's a very thin small line running from the wiring harness to the back of the intake manifold that seems to have holes in it causing another leak. (Probably from the dam mice)

But with these engines a vacuum leak shouldnt change the idle as i've heard? So the leaks cant be the root cause of the idle fluctuation... I'm still at a loss..

 

it can only adjust so far with the iac then it starts to adjust fuel down. large enuff leak and it will idle high. if iac is at 0 i would say its closed all the way trying to slow it down. i would say not having a reading from the tps would be first problem to look at. i think if you have a low tps reading it sets the iac at 0. im gona say a vacuum leak and or tps. lol

 

oh the hose coming outa the haness is the vacuum line for the heat/air/defrost control.

 

Yes there were a few tiny holes in it from the mice I'm guessing, I made it worse by bending it trying to loom at it. Managed to save it for now with some heat shrink tubing.

The plumbing for the PCV looks pretty worn and cracked at the Y connector and the ends. I'll replace that this weekend.

My vac gauge was reading low so might as well start there. Just find it weird that it happened after a TB P&P.. Well, and mice lol

 

there is information missing

what issues were you experiencing prior to performing the above-mentioned work?

How was the car idling?

Coincidences do occur but not as often as one would imagine and allow me to elaborate.

If the ilde was fine prior to the above, and you removed the throttle body and IAC including messing with the opening for the IAC and now it doesn't idle correctly then you know where the issue lies.

The chances of an unrelated hose now with a vacuum leak being the culprit are not very high.

It's always good to fix vacuum leaks so continue doing that but you need to fix the problem at hand which unless you state otherwise, did not exist prior to your removal of the throttle body.


You mention "air box", is that the factory thing with the oem style air filter?

A curiosity, why were you porting/polishing the throttle body? What was the motivation and expected results?

 

What is the purpose of filling the IAC port, and then drilling it back out? Is the opening the same size as it was? If not, I'm putting a $.02 bet on it possibly being an IAC air flow (or lack thereof) issue