PO507 Code help

[Mikz86TA]

OK. For quite sometime now I had this issue. Never did a code get thrown and it really wasnt that big of a deal. Not sure if the PO507 code I am currently throwing is related, but I could almost guess it is.

The Issue :

A year ago or more, I noticed this issue. After the truck is at operating temperature is when it happens. I drive the normal road speed, I come to a stoplight/etc. , I push in the clutch and throw the stick over into neutral and then coast up to the stop. As I approach the stop the dropped RPMs which are close to the idle speed (neutral) shoot up and it revs itself. Usually does this 2x's consecutively and sometimes 3x's.

This has been going on as I said for over a year. It seems tho that it has increased RPMs higher now. Also now with the AC on it has some quirks. But those arent consistent.

Idle is fine. No issues, misses, sputtering, etc.
Before operating temp is reached, Idle is at 780 RPM with the air OFF
Before operating temp is reached, Idle is at 700 RPM with the air ON
After operating temp is reached, Idle is at 820 RPM with the air OFF
After operating temp is reached, Idle is at 730 RPM with the air ON

Also , if I turn the AC on (warmed up or not) , the RPMs shoot to 1000 RPM and back down. Also does that when I turn the air off. Is that normal? I cant remember.

I recently put a new BorgWarner made IAC motor in as a step to correct the issue. But it did not work.
I had previously cleaned the old IAC tip and pulled the TB unit to clean it thorughly on the underside and IAC passage. That had obviously not worked which is why I bought the IAC motor.

PCV is pretty new and checked. I replaced a few of the vaccum hoses that go to the vac canister from the intake.

Ive searched every lead on both the issue and code. Either seems to be linked together. At least not from my findings. Most say replace the IAC motor with the PO507 code. Well, duh! But it didnt cure either one of my issues.

My next ideas are MAF, MAP or I got a 2nd bad IAC. I have a GMS MAF to try out, but I think its bad anyways. Ive heard about leaving the MAF unplugged and may try that also. If it correctss the issue then its a bad MAF? I also though a vaccum leak or a leak at the MAP. Those MAP sensors are loose fitting seems anyways. And the tiny o-ring seems chincy. But if it were a vaccum leak, wouldnt my idle be affected? Wouldnt it do it all the time and not after warmup?

Code will come on after erasing it daily. Doesnt take very long. But other than the reving issue, I dont see any actual idle issues cruising or stopped otherwise. The only thing is the shoot up when the AC is turned on or off. The real bothersome thing is just the damn SES light being on. The rev thing is kida pissing me off now too, but Id live with that over the SES light.

Anyone had the same issue, seen this B4 or have input for any of the steps to take?

THX, Michel

[Mikz86TA]

Oh and one more thing.
I was reading on a Infinity forum post about the IAC replacement , that there is a procedure for resetting it after its been unplugged. In fact they sid the Infinity needs a Tech to do a reset in the event the TB unit is ever unplugged.
I also saw something on the pintle length to be set to prior to install and a ignition cycleing on-off for a specified time and number of cycles B4 you start up for the 1st time.
But my Hanes manual states that there is no adjustment needed to this model IAC and the PCM does it on startup.

Any thoughts or knowledge on that?

[Mikz86TA]

So I still read there is no actual re-set procedure for the IAC.
So I tried this 1st and will see tonight weahter it did sh*t. I unplugged the PCM totally for about 10 min to reset it.

[JONGO8]

When I replaced my iac I just installed it in the parking lot at napa. It has worked good ever sence. Never set it. When I started it up it ajusted it's self.

[Jay_Pollard]

Your revs flare up too eh? Mine has dont the same thing, straight off the lot. Come up to a stop sign or light, slap the stick to neutral, the revs will sit at about 1100-1300, untill I come to a complete stop, then they will drop back down to an idle.. Its weird...I think its a GM thing? my buddy complained about his sunfire doing the exact same thing.

Jay

[bespurcell]

I drove a 2000 full size with the 4.3 and it did the rev thing too.

[Mikz86TA]

I expect it to stay in the RPMs until Im stopped, but it revs a couple times. Up and down.
The unplugging of the PCM may have fixed it. I did nt get a SES light tonight. But Im a bit intoxicated, so Ill need 2 see tomorrow if it actually worked.

[12sws27]

wish i could of helped. but i just didnt have an idea of what it was. but you'll get it right.

[Mikz86TA]

Hope so. Ill drive it around later and see if the PCM reset actually worked.