jbowen1094

I have done a search and have seen other threads regarding this matter but didn't think any of them specifically applied to the same problem I am having:

The misfiring usually occurs at idle and it happens most of the time but not all the time.
My check engine light is not on so there is no code to diagnois the issue.

I have changed the MAS & CPS and it seemed to fix the problem initially but it is back now and getting worse...

Any comments or suggestions would be greatly appreciated..

bbearden

Have you checked all your ignition coils? Have your ignition wires ever been changed? Thats where I would start my search if I had this problem. If this don't produce and results, check the spark plugs.

maverick5.0

it's a long shot,but check your EGR valve for carbon build-up or loose conections!!!!

wnycec

how can you tell if your car is misfiring?

MarcusF

Misfiring, or vibrating a lot during idle? If it's an ignition misfire, it will usually happen during acceleration as well as idle. If it's only during idle, NEVER during acceleration, then it could be a faulty EGR as suggested, or it could be the motor mounts, which are a normal wear item. Bad motor mounts can cause a lot of vibration to come through.

jbowen1094

If it was an EGR issue wouldn't it misfire constantly? I just drove it at lunch and no problems whatsoever. Engine Temp was up to the 194 range according to the scale on the climate control.. Does this seem too hot?

bbearden

I don't believe that 194 is too hot for our motor. All aluminum motors like the LS-1 and LS-2 from the Corvette for example run around the 200-210 range. You get no problems or bogging under heavy throttle input? Might try looking into the EGR to see if that is causing the problem.

jbowen1094

Check engine just came on last night going home from work. Still running like a champ.. How do I get the check engine light code?

jbowen1094

Changed MAF, Reset CPU, and it seemed like it was running like a million bucks. In fact I had a great run against a new WRX. Got to a stoplight after about 20 minutes of driving and it died. Threw code 2004.

John 99CLK430

Raced after getting new MAF and ECU reset and didn't give it time to let it settle in no wonder.

But seriously, did you do what Marcus said? I think it's a very good chance to do w/ EGR AND/OR the ignition.

rubberninja

have you changed you're plugs lately? if so check ur leads and wires...hell id check em anyway. GL!