Going to out to the GMSC Bash, whenever I started my car it wouldn't idle and throwing codes. In 1st gear it couldnt do anything, once I got out of 2nd and so on perfect. Then once I got it back into 1st gear it would idle fine. Then when I got gas i had about 1/4 left, so I was goning to fill up. It stopped at $20.00, roughly 8 gallons? When I started it up, it said 3/4 full and still wouldnt idle right. That night I autotapped and I was running lean, and had a MAF (Mass Air Flow) problem. I was gonna have a dealer come out to get at the Bash, but come to find out my air intake came undone, like someone unscrewed and just let it barely connect. a GM dealer still brought out a tech-2 and checked it and cleared some codes.

Oh here is really good news I took my car into get the sunroof trim re-installed that Monday and they said I have a bad crank sensor? I do believe that is what he said. Thats just great.

 

So you found the intake duct work fell off, you,re not alone. The first SS we got at my shop would not idle right either, so it was given to me the clamp to the thottlebody was not tight and came off. Unmetered air was entering the engine. On GM's forum some Techs wre discussing the same issue it seems many though parts at it to try to fix it. There is a bulletin for the duct work. Engineers called me twice to ask questions, also the bulletin states that if the oil dipstick is not properly seated it may cause the same problem.

 

cool I'll bring that up when I go get it fixed.

 

New bulletin released. Your air filter may be what is setting a DTC po171, lean mixture. Have your dealer look up DOC ID# 1684652. This bulletin came out on 7/15/05. Hope that also helps.

 

Do you have any more info on this bulletin? I have a Red Line and this is the code I get with my K&N CAI installed. However, I can use the same K&N air filter with the stock intake tube (like a short ram) and there are no codes. Any help is appreciated. Thanks.

 

As per this bulletin, the stock air filters folds may be too closely packed together and may be throwing off the MAF sensors readings. This condition is found to be accuring on a highway cruise. The fix at present time is to replace the filter. As far as an answer to why you are setting lean codes with the CAI puzzles me, but some thought though, You must be sure no air is entering after the MAF sensor. Any leaks will be unmetered air and be read by the PCM as lean. Let me also get into something else here, There was some chat on GM's Tech forum about this air filter topic. They were assuming a restricted filter was causing the lean code, and that a K&N filter may be a fix. As a Tech I have fixed vehicles that had drivebility problems that were caused by a K&N filter do to over oiling. Oil gets drawn off the filter and contaminates the elemant of the sensor, this causes the PCM to increase the current flow over the elemant to sustain the proper voltage drop. An increase in amprage is interperated as more dense of an air charge. The PCM will then increase injector pulse width to add more fuel. The problem is you don't need more fuel because the reading is false. This ends up as a rich mixture and possible DTC's. Now as far as a resticted air filter causeing a lean condition , I don't see it possible. The MAF sensor WILL read the actual amount of air entering the engine, but the PCM is programmed to see specific data readings from its sensors under given RPM, speed,temp.,load, etc. If anything is out of its window the PCM will attempt adjustments. If it needs to adjust too far a DTC will set. So a restriction is a lack of air, not enough for the pre-programmed data, the PCM will back off fuel and set a RICH DTC. Sorry about running on about this, but I have been told I'm too technical sometimes.