YellowStreak7

Hey everyone, I am new to this forum, but have been a part of other forums, and have always found them useful. I am sure this will be the same, so thank you in advance!! I have a 2004 Chevy Suburban 1500 4WD 5.3L Flexfuel. I had a really rough idle, and it had been this way for some time. We never got it checked out and drove it that way for months. I finally had a friend check it out and he found codes in the computer that said cylinder #4 misfire, so he pulled the plug and found that the spark plug tip was completely gummed up with oil, so he replaced the plug and wire on that cylinder, but it still seemed to have a rough idle. So he got a noid light kit and tested the harness on that injector and found that it was not lighting up. He traced the problem to a break in the wiring and reaplaced the connector with a new pigtail. The noid light now blinks, and the injector registered about 15 ohms resistance, which I read somewhere is normal. Started it up again, and the vehicle still has a weird slightly rough idle to it. Pulled codes again, and this time it came with a code P0101 for the mass air flow. He disconnected the MAF and the vehicle seems to run perfect. Does that mean that my MAF is bad and that it will fix my problem by replacing it? Is there a way to test the existing MAF before I go buy another one seeing as electrical parts are not returnable once they are installed? Also one of the times after replacing the plug and wire the vehicle threw a p0200 code for injector circuit malfunction. Thought that one had to do with the break in the wiring, but thought I would include it just to give you guys all the info. Thanks again!!

Joe In NY

hmmm. maybe. When our 2002 had a rough idle it was first from old spark plugs and dirty injectors. Then a year later the intake gasket started leaking, got it replaced and ran smooth.

Your mass air flow might be bad, i would go original factory. they are surprisingly cheap straight from gm. Last I looked around $80 i think... After market $200...

Careful if you drive with out the mass airflow, it can be fun though. The tranny shifts REAL firm with out the mass airflow plugged in (found this out on our 2007 a few weeks ago haha)

YellowStreak7

So I replaced the maf sensor and it seemed to run different than with the old one. A little better but I still have a slight rough idle so I pulled the fuel rail up to see if all if the injectors we working properly and it seems as though they are. So I pulled the remaining spark plugs out and found out of the remaining 7, 5 were really gummed up with oil on the tips. Can anything else besides bad rings cause that? Like maybe intake gasket leaks? I haven't pulled compression on all of the cylinders yet but I did do it on cylinder 4 and 2 and I got 180 out of 4 and 200 out of two. I'm going to pull compression on the rest but wanted to know if there is anything else I could do or check. Thanks!!

oldchevy

You can try going to a hotter plug. It won't solve the problem, but it could make it run better till the problem gets worse.

YellowStreak7

Do I have to run iridium plugs or could I put platinum in?

Joe In NY

sometimes its best to run factory equipment. and in this case its true. GM uses factory Iridium plugs, and GM motors actually dont like plugs other than AC-Delco OE Iridium Plugs. Just go to Advanced Auto's website and get 8 of em' and use their online discount. I did for my burb a couple weeks ago, raised my MPG by about .5mpg and idles much smoother. I went from factory plugs with 121k to new plugs...

in2pro

I agree go with the factory plugs, can't go wrong.... you may also want to clean the throttle body... there is a TSB about a rough or unstable idle that is even more pronounced when the AC is on...

search for Bulletin No.: 04-06-04-040