Stumble at take off when cold

[spacemonkey]

Like title said.When it is cool or cold out when I start to take off there is a slight stumble.Thats the only time it does it.Starts,idles,runs and drives great other then that stumble.Everything is still factory under the hood.I have done a full tune up.Plugs,wires,and fuel filter.Cleaned the tb,maf,and the iat.Only thing I haven't done is the o2's.Can anyone give me any ideas what else to check?I could live with it but being injected it should not be "cold blooded" right? I did search but found nothing helpful.

 

[Labora]

I've had a bad set of 02's cause this, until the car got nice and warm it would not run correctly. (It also thru a code to show this so if you can check for it do so.)

 

[HISSIN50]

Absent codes, I'd want to check the ECT voltage when it's cold (acts up).

Good luck.

 

[MLC Stang]

spacemonkey,

That’s two votes for a bad Engine Coolant Temperature (ECT) sensor. But there’s another possibility as well.

I had the same problem, a stumble just barely off idle when I just got the first bit of pressure on the gas pedal. If I stomped the gas pedal down faster, the stumble was less noticeable. The more gradually I started off the more noticeable the stumble was.

For a while it only happened when the engine was cold, but then eventually it started happening at other times as well.

HISSIN50 figured my problem out. (I still owe him a beer!) I turned out to be a bad Throttle Position Sensor (TPS). There was a bad spot on it just off idle, which I was able to verify by back-probing the wires to it and reading the voltage with an old analog VOM as I opened the throttle by hand.

I replaced the TPS and my off idle stumble was gone.