compgt10

I have this inconsistant sputter/shudder problem at Idle.. I've cleaned the MAF, the Injectors, new Plugs, as well as new O2 sensors (upstream)... i know the problem isn't normal so I'm wondering if anyone happens to know what this problem is? Is it a bad coil-on plug? is it a bad fuel injector? or does my ECM need a reflash?

PLEASE HELP!

Bman2000

is it possible your having fuel pump problems? that would be my guess, failing fuel pump can really screw with the way the vehicle drives. i would doubt its a cop unless its more of a miss.

compgt10

can't be fuel pump.. it'll only shudder during idle after that nothing runs like a champ

ShadowDrake

Personally I wouldn't totally rule it out. It's still a possibility - the fuel pump voltage is variable.

Start doing some basic testing. Unplug the coil and fuel injector to one cylinder. Start the car. See if the sputtering changes or goes away. If it doesn't, plug that cylinder back in and unplug another. Repeat. That should narrow it down.

compgt10

we have gone through and unplugged each fuel injector and the shudder was constant

cliffyk

Are you running the stock intake, is the MAF screen installed?

Do you have a wideband O2 system, can you data log the AFR at idle? If it's bouncing all over then uneven flow through the MAF could be the culprit.

massred98gt

egr may be stuck open. or possibly a vacuum leak somewhere. my gues is a small vacuum leak.

compgt10

I am running a Cold Air Intake and the screen is installed and clean... but the problem was occuring when everything was stock... vacuum leak seems to be the popular vote i just don't even know where to start lol either that or I have a bad injector

Bman2000

i wouldnt rule out fuel pump, mainly becuase we had one at work that ran fine at idle but crap wheny ou got on it, im sure it goes both ways. Youll have to ask cliffk on this but doesnt the car run without the MAF pluged in? obviously it wouldnt be that well, but i think it does so id say unplug and see if it runs better. if im wrong sorry!

compgt10

well we did a fuel pressure test last night with a gauge and a scan tool... neither were consistant numbers, the gauge was bouncing between 26-35lbs and the scan tool was bouncing between 38-40lbs, we didn't have enough time to get deeper into the problem so in 2 weeks when i get back to class we're gonna check with a new gauge. So it is something with the fuel, we're thinking either my pressure regulator or my fuel pump. if any of you could tell me anything with what i have just told you that would help greatly.

thanks for all the help so far

btw... BMAN no answer is a wrong answer i'm lookin for help and you're giving me ideas of things to look for.. i will try the MAF test you told me and see what happens