Low speed idle shudder

DaRockwilder · 03-27-2007, 09:28 AM

I'm having a small problem with my Ecotec. Sometimes when I rev the car a bit, and the RPM's drop down again, they fall too low and the engine almost dies, but then brings itself back up. The same thing happens when I'm idling and then turn the fan on. It'll *almost* stall and then perk back up.

I noticed my Fuel Pressure Regulator is leaking a bit where the two halves meet, and I could smell a bit of fuel in the vaccum line to it. Could a bad FPR be causing this problem? Seems pretty likely to me but I just thought I'd double check.

Thanks all!

Gr1m · 03-27-2007, 09:52 AM

my car does the same thing on my 3400, if u tap the gas the RPM will go up, then drop and then raise back up like you are pressing the gas, when really you arent, i just figured it wasnt a big deal but if anyone knows the problem let me know

DaRockwilder · 03-27-2007, 10:06 AM

I didn't think it was a big deal either until it looked like my FPR was leaking a bit.

Gr1m · 03-27-2007, 10:14 AM

lol i havent checked anything, oh shit i forgot i have to change my oil today! thx for the reminder hahah

AGT · 03-27-2007, 10:16 AM

Mine did that but threw a code and turned out to be a O2 sensor on the down flow

Gr1m · 03-27-2007, 10:20 AM

nah no codes for me not sure what it could be i just got used to it after i almost hit a few cars at drive through lines an such

AGT · 03-27-2007, 10:22 AM

Quote:

Originally Posted by Gr1m

nah no codes for me not sure what it could be i just got used to it after i almost hit a few cars at drive through lines an such

Haha

"Move damnit. I'm Hungry!!"

Gr1m · 03-27-2007, 10:24 AM

no.. its like it would be giving the car gas while i have my foot on the brake and i would accelerate forward for a second then it would drop back to idle RPMs lol

DaRockwilder · 03-27-2007, 10:29 AM

This isn't the same thing. Mine drops below the normal idle.

I just made a video showing what happens.

I'd also appreciate it if you guys wouldn't whore my thread. Thanks!

AGT · 03-27-2007, 10:35 AM

Quote:

Originally Posted by Gr1m

no.. its like it would be giving the car gas while i have my foot on the brake and i would accelerate forward for a second then it would drop back to idle RPMs lol

I had the same thing as both of you. I know exactly what you are talking about.

Quote:

Originally Posted by DaRockwilder

I'd also appreciate it if you guys wouldn't whore my thread. Thanks!

So you are getting leaks around your FPR. Most would say check your fuel pressure and oxygen flow and last time I checked, we both have been asking questions and giving suggestions.

DaRockwilder · 03-27-2007, 10:37 AM

Yes, you both have been asking questions and giving suggestions. This however?

Quote:

Originally Posted by AGT

Haha

"Move damnit. I'm Hungry!!"

AGT · 03-27-2007, 10:40 AM

We've stayed on subject...let it go. So you do not have a code and that is the only thing odd mechanically with your car?

DaRockwilder · 03-27-2007, 10:45 AM

No codes, and yes. Thats the only thing. I changed the fuel pump a little while ago, and just did new plugs yesterday. No change. The fuel pump actually cratered and Its time to do the plugs, I didnt change both just to try and fix this.

It also only does it when the motor has warmed up. I've got a fuel pressure gauge, I just haven't checked what the pressure is doing when it happens yet. Probably will today.

antichrysler · 03-27-2007, 11:25 AM

I'm no car expert... but my Alero is always doing stupid stuff like that. I say start from the ground up. Go fill up with a tank of premium, throw some fuel injector cleaner in it and some condensation remover. See if that makes it any better.

AGT · 03-27-2007, 12:04 PM

Quote:

Originally Posted by antichrysler

I'm no car expert... but my Alero is always doing stupid stuff like that. I say start from the ground up. Go fill up with a tank of premium, throw some fuel injector cleaner in it and some condensation remover. See if that makes it any better.

He's right...buy the cheap fixes 1st and hope they do the trick

Cliff8928 · 03-27-2007, 01:12 PM

Mine kinda does that too, not as bad since my idle is higher (because I have a 5-speed). I wouldn't really worry about it too much. However anything leaking fuel should be a concern.

DaRockwilder · 03-27-2007, 01:31 PM

I've ran premium in the car since I bought it months ago. I also threw a bottle of concentrated cleaner in the car when I bought it as well.

I'll keep my eye on the regulator. Its not leaking much, just had a trace amount of it on the outside.

Thanks for the replies all!

slalomking · 04-09-2007, 10:34 PM

bone stock 2003 Ecotec w/ automatic. Same damn thing. Seems to be worse in warmer/hot/humid weather.

I noticed this 1st summer of the car's life, when it was 6 month old. Dealer was no help (no codes, we can't help you).

Sometimes in worst cases it does in fact stall out unless I keep the revs up to 800 RPM via the accelerator.

I liked the video idea. I should have done that 3-4 years ago, and shown it to the dealer!

Good luck. This may wind up being one of those 'ya gotta live w/ it' things.

DaRockwilder · 04-09-2007, 10:45 PM

Yeah I'm not going to worry about it anymore. Seems like its just one of those things it does.