96' Olds is very eager to go in the morning

[nuts32605]

I have a 96' Oldsmobile Ciera Wagon with a 3100 V6. The car always starts fine, but if the engine is cold, then it starts... kinda tapers off in rpm and then... revs like there's no tomorrow. It will do 35+ mph without your foot in the gas. The only thing to stop it is to shut the engine off and restart it. From then on the car behaves very well. The idle is not buttery smooth, but it's not rough either. It only races when it's cold, but I can't figure out why. The computer hasn't thrown any codes and I replaced several old, worn out vacuum lines, but that has failed to solve the problem.

BTW... I got a haynes manual for the car but the pictures of the engine don't match what I have under the hood. Is there an I.D. # somewhere on the block or transmission?

[SilentWing]

Honestly it could be a few different things, but my advice would be to check out the IAC motor, but it can be difficult to check this since without a computer scanner you'd need to take the IAC motor out of the throttle body, and you have to be really careful not to strip the heads off the screws or snap them off. Maybe someone else will have other ideas for you, I'm just throwing it out there that it could be a sticky IAC motor.

[Prospeeder]

shouldnt have a problem breaking or stripping them if you use the correct torx bit screw driver....... Clean the IAC valve, and its port in the throttle body. if you have a scanner with live data mode, you can easily make sure the Throttle Position Sensor is adjusted correctly, or reading bad. If shutting the car off and restarting it fixes it for awhile, maybe even the ECU

[nuts32605]

Well I have a computer scanner but it does not have a live monitor function. I think the TPS is fine though...

Before the car used to throw codes all the time but since I've run a tank of gas through it the computer hasn't complained once. It probably had to do with the old gas (the car was left sitting in a carport for ~3 months). In case it helps these were the codes it USED to throw.

TPS range/performance fault
Bank 1 too lean
TPS intermittent

But it's been three weeks and it's not said a word.

[spyderdiablo]

check vacuum lines near the pressure reg.

[nuts32605]

I removed the IAC and tested it like it said to in the Haynes manual. I should have >20 ohms across terminals A & B and C & D. I have no resistance so I guess it's bad...

@spyderdiablo: I checked all the vacuum lines and they're in good shape (especially since I replaced some old ones). The regulator hose will pull vacuum and when I disconnect it the RPM's increase as they should.

Thanks for the help guys. I turns out I won't be keeping this car as I thought... :( But at least the guy after me won't be having any trouble.

[nuts32605]

Nope, that wasn't it. Replacing the IAC did nothing. I have no idea what is causing this... :dunno: and I can't find my code scanner so I can't see if there are any codes on the computer.

[Pontiac6ksteawd]

I know how to fix this in OBD1, but you have OBD2, and I have no idea.. I would normally recommend unplugging the battery on the positive side, then touching that positive lead to some metal to take out any residual electricity in the system. Letting it sit for about five minutes, and reconnecting the positive battery cable. Then doing an Idle Relearn....

But as I said, you have a OBD2, and I have no idea how it works with that system. Its not as easy as OBD1.

[Prospeeder]

Well 3 months isnt gonna make gas bad, i just bought a car that sat 8 years and when i put a new head on it, it fired right up and ran perfect on the shitty gas, my 6000 ran perfect on nearly 2 year old gas. I wouldnt attribute that sitting/gas to anything, All of my cars i have bought have sat at least 1 year or more.

[Pontiac6ksteawd]

Agreed. The only time I have seen a issue with old gas is in carbed cars cause the gas gums up the jets and that, and the older gas doesnt atomize as well. But with FI, when the Injector is off, its off. Nothing for the fuel to gum up, and a injector atomizes the gas for you..

[nuts32605]

Well there might be a vacuum leak from the crankcase evap on the rear valve cover. The fitting for the hose has some molded-on plastic elbow thing with an integrated seal. After ~13 years the seal has worn down so now it just sits in there. Autozone and Advanced auto parts doesn't have the part, how can I build up the seal? Teflon tape maybe? or some kind of RTV sealant?

[Prospeeder]

Dealer....

[SilentWing]

I think I know which one you're talking about, you might want to check with a GM dealership, it's a tad bit pricey though, but if you ask the parts department they should be able to get you a blow up diagram... just make sure they give you the 3100 and not the 3.1 multiport.

[nuts32605]

I fixed it. It was two bad hose gaskets. The fitting for the PCV -> intake manifold was completely missing, and the hose that connects to the back valve cover was loose. I replaced both with generic rubber fittings, since autozone nor advanced auto parts didn't stock it. Now it's running very well, thanks a lot guys. :)