stumble when accelerate/rough idle

[godless-phoenix]

couldnt find anything on any other threads, but lately my car will have a rough idle and stumble for a second or two when accelerating from a stop. Its on and off and only happens after the car has warmed up. ive cleaned my MAF, throttle body, and ive also run fuel injector cleaner though it. i changed the plugs and wires last year in march, replaced all O2 sensors, and replaced the fuel filter last year as well...no check engine light either, any ideas? thanks!

[KMdef9]

Check fuel pressure at the rails.

[godless-phoenix]

yeah i hope its not my fuel pump whats the pressure supposed to be at? like 60-65 lbs.?

[KMdef9]

About there, I think 48 @ idle Iirc.

Jon has the numbers.

[godless-phoenix]

its weird cause it only happens after the engine has warmed up to operating temperature, its on and off, and the car runs fine after i accelerate from a stop...just a rough idle and stumble when accelerating from stop for like a second

[Knight]

You should see around 58 psi at the rail. You could still have it scanned, as it may have a code pending.

[Knight]

When you replaced the O2 sensors, what brand did you use? Also, if you did it while installing LT's, did you splice the wiring, or run ones with longer harnesses?

[godless-phoenix]

You should see around 58 psi at the rail. You could still have it scanned, as it may have a code pending.

i have a code scanner, and i actually did that just to check anyway...zero codes

[godless-phoenix]

When you replaced the O2 sensors, what brand did you use? Also, if you did it while installing LT's, did you splice the wiring, or run ones with longer harnesses?

i used cheap ass SMP (standard motor products) O2 sensors from ebay that were like $20...i have stock manifolds

[godless-phoenix]

btw...what does iirc mean?

[Knight]

iirc - if I recall correctly.

[godless-phoenix]

iirc - if I recall correctly.

ahh, derrrr! damn acronyms haha

[smokestack]

If you have a scanner make sure the cheap sensors are in spec or working. I bet if they are working not within spec and have your fueling messed up. Went through that myself. No codes but did not work.... Had to replace them

[godless-phoenix]

If you have a scanner make sure the cheap sensors are in spec or working. I bet if they are working not within spec and have your fueling messed up. Went through that myself. No codes but did not work.... Had to replace them

i have a cheap $80 scanner that only tells me what codes pop up. Doesnt even tell me what the code means, so i have to look them up...

[JayTA98]

It might be the O2 sensors out of specs like mentioned. Alot of the members use the boschs. Have you check the IAC? I had a few cars that it was stuck and dirty with carbon deposits. It never threw a SES light. I pulled it out cleaned it real good and made sure it was not stuck. It solved the idle problems.

[firestar]

I have been chasing the same problem for about a year now and followed the same path you're on (changed plugs 4 times - never had a car that was so painful to change plugs!) Anyway, after cleaning and/or replacing all of the things mentioned above with no fix, this week we found that the MAP sensor is not working. I finally found a guy who had the right equipment ( a sophisticated scanner) and he had time to go through everything, like what does the computer think the O2 is and what does a gauge in one of the bungs see, etc. Another often-quoted possiblity was a leak in the intake - we sprayed carburetor cleaner around the hoses, manifold, etc., with the idea that if it hits a leak the engine will respond. Good luck!

[Intimidator02SS]

try disconnecting your mass air flow sensor and see if symptoms disappear.

[godless-phoenix]

It might be the O2 sensors out of specs like mentioned. Alot of the members use the boschs. Have you check the IAC? I had a few cars that it was stuck and dirty with carbon deposits. It never threw a SES light. I pulled it out cleaned it real good and made sure it was not stuck. It solved the idle problems.

how do i check to see if the iac is stuck? i know take it out, but do i just push it in or turn it? dont want to mess that up, cause for that little part its expensive! taking it in next tuesday to have it checked out cause im stumped...

[KMdef9]

how do i check to see if the iac is stuck? i know take it out, but do i just push it in or turn it? dont want to mess that up, cause for that little part its expensive! taking it in next tuesday to have it checked out cause im stumped...

It moves by electricity, controlled from the PCM. Just give it a good spray/wipe down and reinstall. DON'T pull on it.

[godless-phoenix]

It moves by electricity, controlled from the PCM. Just give it a good spray/wipe down and reinstall. DON'T pull on it.

should i spray it with maf cleaner or throttle body cleaner? thanks for the tip on not pulling it btw haha