tap the gas at idle... almost stalls

[cutlass1991]

I've noticed this for a while now. Say I'm at a stop sign and the engine is idling, when I go to accelerate, there is a slight pause like the engine just stopped running for a split second. The engine drops in rpms and then jumps back up and goes fine. Sometimes it's bad, sometimes I can't even notice it. But it seems that if I really try, I can get it to stall sometimes by just tapping the gas pedal once very quickly. But if I press the pedal slowly and gradually, there is no problem at all.

This happens whether I am in gear or not. Any ideas?

[Stevo]

Exaust manifold? Catalytic converter full?

 

Too much rush at the exit. Kinda like as if someone covered the tailpipe?

[DiscoStudd]

Any trouble codes being set? My first thought is the Throttle Position Sensor, followed by the MAF (mass airflow) sensor. If your MAF is bad, you can unplug it and the ECM will set a default airflow table, allowing the car to run normally (albeit not at top efficiency.) The TPS is like a rheostat, and over time wears out in certain spots causing the throttle response to lag.

 

Either sensor going bad will illuminate the Service Engine Soon light...

[Sleek 93 SE]

Oh wow, same thing is happening to me. I got a service engine soon light. A shop was supposed to have fixed the light when my car wouldnt start. Now its back again. but my car does the same throttle thing.

[cutlass1991]

Good, at least I know I'm not alone. So far my engine has just under 60,000 miles on it, and I baby it as far as driving style and general maintenance is concerned. I never got a service light for anything, except once when I installed the WAI, I forgot to re-connect the IAT sensor to the intake pipe. But as soon as I did that, it went away. The exhaust is tight, no leaks. And I'm pretty sure my cat is ok, even though my exhaust stinks like sulfur most of the time. Looks like I will be playing with the sensors DiscoStudd mentioned and see what effect they will have on this. By the way guys, thanks for the quick responces, this forum is awesome.

[JoroCorona]

Sulfur = Bad Cat

 

Get the cat replaced and figure out why your car killed the ca in the first place.

[1990lumina]

My Lumina does that too...but only when it is in park. While driving all is well

 

- Jeff L.

[sonyman87]

Idle air control.. sounds like your chokeing it.

could also be bad plugs

[Jcrow]

Mine used to do that, but it went away.

[Stealth]

mine does that too, sometimes its real back other times its fine, it should be noted that teh entire exaust was replaced last year even tho its leaky and loud from what I can tell, and th eplugs were replaced liek 3 weeks ago

[cutlass1991]

I changed the plugs, wires, and also have new mufflers. Aside from bad sensors, do you think changing the plugs or wires could do this? I'm using delco rapid fires and auto-lite wires.

[3pt1lumina]

Dad's 97 Lumina is doing that... Plugs and wires made a difference, however, maybe it is a clogged injector(s)?

[Tru2Chevy]

My Lumina does the same thing.

 

I was thinking it had something to do with the intake gaskets (original) or the lazy o2 sensor (also original). The car has 181k miles on it. Plugs and wires are less than a year old, and the cat is fairly new too.

 

- Justin

[kcac]

I was experiencing the same "hesitation when accelerating from a stop" problem that cutlass1991 described.

 

My mechanic diagonosed the problem as aa weak fuel pump - it just wasn't putting out enough fuel pressure. A new fuel pump and the car is running normal again.

[cutlass1991]

You know, I think kcac might have made an interesting point that we all over looked. A bad fuel pump would also explain why this problem comes and goes. As I read on that long drawn out post about fuel pumps and thermodynamics, maybe as the tempurature changes the pump gets weaker. This seems like it is worth looking into. The only question now is if changing the pump yourself is a bitch or not, and of course how much will it cost.

So from here my plan of action will be to change the O2 sensor, and if that does nothing, look into the fuel pump. hopefully this will get solved.

[regalguy26]

i have had that prob for awhile now, any of your fuel pumps gran when you are comming up on low fuel , liek when you stop it groans?

 

 

mine does it with no cat

, new wires new plugs

[kcac]

My fuel pump never sounded any different to me. A fuel pressure gauge was the only way to know for sure in my car's case.

[regalguy26]

your fuel filter is pluged to shit i bet, i cant even blow air thru mine as i discovered today changin a peice of cracked fuel ine, ill see in the morning if she idles like shit after i let off gas and stop and stall prob.. and when i get low on gas if it still wines..casue come to think about it, i havent ever changed my fuel filter i dont think...

[Tru2Chevy]

I have an o2 sensor and a new fuel filter to put on, hopefully that will help. If not, then oh well.....

 

I'm looking at a Z34 for cheap

 

- Justin