Surging Idle Upon Start

[shields]

As I start the car in the morning, the idle bounces up and down until the engine is warm. then it stays steady.

I've also been experiencing sudden hesitation and stumbling as I accelerate. This is not a misfire, no smoke or noise at all. Just a stumble that may sometimes last a few seconds as the power is greatly decreased momentairly.

All my electrical components are all brand new.

Are these symptoms of a dying fuel pump?

If so, which one? I know there is an inner one and outer one...

Thanks in advance.

[///M Powered]

I'd like to know as well, i have the same stumbling problem, jsut replaced FPR and filter to no avail.

[jrdn223]

exact same problem here. couldn't describe it better. would love to know the answer.

[clutterbucker]

O2 sensor maybe? Idle air stabilizer? I started my car yesterday and it immediately jumped up to 3500 rpms and accelerated to near four until I tapped the throttle and it went back down to normal. Bouncing idle is also happening once ina while with me, and the only two things I can come up with are O2 sensor and Idle Ait Stabilizer. Whenevr I get a chance, I'm going to pop it out, apply a charge, then see if the stupid thing opens. If not, we've got the answer.

[M-technik-3]

Gonna say it's maybe a idle stablizer or O2.

[Jarvis]

O2 sensor maybe?

Bahhh. for like the 10th time this month: the O2 sensor does nothing until the car is warmed up.

You said you replaced all of you "electrical components"? Including ignition wires, ignition coil, distributor cap and rotor? They might have something to do with your stumbing during acceleration.

[Jarvis]

I started my car yesterday and it immediately jumped up to 3500 rpms and accelerated to near four until I tapped the throttle and it went back down to normal.

Only time that's ever happened to you? I had a similar problem once. The car would idle at 2K unless the revs were pulled down by upshifting. Revved to 5K once when I started it up, too. Turned out the throttle cable was really bent and would occasionally get caught on various parts of the throttle body.

[e30Matt]

lol, my Talon does this too. Lots of cars do it, we just refer to it as "auto-rev." :)

[clavinZERO]

after I checked the throttle plate screw on my throttle body, my cold start rev-bouncing issues disappeared. The Bentley says the butterfly valve on the inside is to be set at .0015 inches clearance from the wall of the TB. Having this set correctly allows the FULL-THROTTLE / IDLE SWITCH to operate properly, giving the ECU the correct signals. How this actually helps things?... I am still a little hazy on HOW that might have fucked the starting of a cold engine. Maybe because if it's open to far, too much air is getting in during warm up.

[shields]

Just replaced O2 sensor. No difference...

[ryan_george]

Bahhh. for like the 10th time this month: the O2 sensor does nothing until the car is warmed up.

[shields]

Yah I know, I meant it did nothing about the hesitation. I think it's the fuel pump. But will get it properly diagnosed before forking up any more cash.

[coupeowner]

Try shooting carb cleaner through the idle control valve. Just unplug the side coming off the intake boot and spray the hell out of it. They tend to get gummed up causing the idle to bounce. If it helps, you may want to pull it off and give it a really good cleaning.

[shields]

I've already cleande the entire system out with a rag, toothbrush, and fuel injector cleaner. It's spotless. The hesitation is much worst today. I have to get it checked out soon. I have a feeling I'm gonna get stuck somewhere...
I'll update once I diagnose and fix it...

[Kondour]

how about an corroded c191 plug? I had a rough idle and hesitation and my car finally just died. Maybe this is what you are experiencing.