hello all. I just bought a 02 Tahoe,93k miles,5.3,4x4 ls. Ive got three codes and truck runs rough only on a cold start- 45* or colder.
I'm an ex-gm tech,but electrical was my job, never did much on driveability.
1) p017 bank 1 lean
2) p0174 bank 2 lean
2) p0300 random misfire.
i dont think both o2's would go bad at once since both banks reading lean.i think its something common for all cylinders. i did some matinence;
1) new plugs/wires
5) unhooked vacuum on FPR and no change....
anyone seen this before? going to check fuel press this weekend. scanned again this morning when it was running a little rough and only pulled the 300 code, no o2 codes. any thoughts. clean injectors? bad MAF? gas cap (even though no 400 codes?)
thanks in advance, Gary.
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I chased a problem like this on my 97 Z-71 for about 6months, turned out to be the MAF. We even tried cleaning the old MAFwhen chasingdown the problem. This was in 04 and while at SEMA I was speaking with a rep from Granatelli and he suggested for me to try a new MAF, so they overnighted one to the shop and the guys installed one and all my codes went away and power was restored. My problem was mostly at start-up. If I would try to accelerate while cold the truck would stall. Also while trying to pull a load it was very slugish and had poor fuel economy.
Hope you find the problem and Im sure someone will pitch some info in.......
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Thanks for the reply; I hooked up a scanner and read the same codes you have PO171, PO174 and PO300. Sounds like I have the same problem. I read through other posts with similar issues, and recommend cleaning out carbon build up from throttle body. I don't think this will completely solve the problem, but may help a little with rough idle at cold start. If it doesn't help, I'll be seriously looking into replacing intake gaskets.