Rep Power: 0

I know this issue is beat to death, again and again, seemingly unsolvable issue. Live data shows no issues, no codes, I cleaned the original IAC, it was real dirty, no big change, so I purchased a new one from Ebay, put it on today, still bouncing. The car ran fine before I changed the head gasket. I've read all the forums and rechecked things, nothing seems obviously wrong as in many other cases.

 
Rep Power: 224

What brand is the IAC?

 
Rep Power: 0

Also need to mention, the old valve did settle down to an idle speed but only when the car was stationary, if the car rolled the idle bounce stated again. Installed the new one and it idled at 1500 cold then after 30 secs it started bouncing, this morning the engine wouldn't start, it tried but no go, I push started it and it started and ran fine, been restarting fine. That tells me either a vac leak or the IAC is open too much, too much air for cold start. And like I said, prior to the head gasket repair it ran fine except for the overheating issue. I have a spare engine that I know ran fine so parts swapping is the way I need to solve this. Just doesn't make sense, if I had vac leak why would the old valve idle fine stationary? Right now I going to try closing the minimum air rate screw on the TB, I will mark the original position so it could be undone if need be.

https://www.ebay.com/itm/403354125745

 
Rep Power: 511

You try doing an idle re-learn procedure after swapping the IAC?

Also, I'd pursue the possible vacuum leak aspect, too. Vacuum leaks on the D17, in my experience, can cause a ruckus for no reason, no matter how small. Testing/searching for vac leaks can be done one the cheap, if not free. Idle relearn is def the cheapest (read: free-est) option to start, and if it fixes it, then you're good to go

 
Rep Power: 0

Its not a relearn problem, I can rule that out 100% I now have a IAC and PCV air leak code, never had those until I installed this new IAC. I screwed out the idle screw all the way, throttle closed completely, still idled high, so I partially blocked off the IAC port in the TB and the idle came down and was not surging. So... that means either I have a huge vac leak somewhere or...the new IAC itself is the leak. So the ECU is actually trying to control the idle with fuel cut, I can see that on my scanner. TPS and MAP signals look fine. But then how was the old IAC able to control the idle when the car wasn't moving if I had a vac leak? It only surged when coasting.I can't find any vac leaks, the PCV hose and valve are new, brake booster holds vac, there is one small vac line port above the PCV that is plugged. What other place would leak except the gasket, and I was very careful when I installed it, I put in new rubber rings and the metal gasket, new TB gasket. The question is, if I can can control the idle by partially blocking the IAC port, why would the valve not be able too? Unless its bad.

 
Rep Power: 0

Covering the mouth of the TB completely killed the engine. Covering the IAC port partially slows the idle to the correct rpm.

 
Rep Power: 222

Need an oe iac

 
Rep Power: 0

I need to re-mortgage my home to do that.Tomorrow I'm putting on a OEM spare, just got to drive and pull it. Stay tuned.....I have 2 from an auto and one from a 5 speed, not sure what the difference is, they look the same. I'm gonna find out. Price range on these is crazy 20 bucks to 400 bucks. Never seen anything like it.

 
Rep Power: 222

Junkyard if you don't want to buy new, needs to be the same as whatever trans you have.

 
Rep Power: 0

Went and got a used one runs perfect now, issue SOLVED!! Don't buy that junk off Ebay!! Makes me wonder if the other brands like Walker or Standard would actually work? I pulled 3 IAC valves, only one was 5 speed, I'm gonna see what the diff is.

 
Rep Power: 222

I've had some Standard products work, haven't tried an iac