Hellllpppp!!!!!!!!

[C-WAY]

Might be time for new cats. A friend had the same problem your having and replaced the cats and the code went away and it ran fine.

[CoupeDevilln]

It is stock, bought in Dec. Ok, I'll check the intake temps. I'll price a fuel filter, prob needs one anyway. And price a fuel filter. The sounds seems to be in center of the engine. Not louder on either side. Thats why i thought intake leak, that and would explain the MAS code.

Oh and no there was no indiviudual misfire codes.

I'm kinda leaning toward a fuel prob, cause I didn't see any smoke out of the exaust like the fuel wasn't burning. Let you guys know what I find.

[NITROUS]

Don't you think you'd see a MAP code if it were an intake leak? If it's the intake put a water hose on it and you'll really hear it or try spraying carb cleaner around the area you think it's leaking and the rpm's should increase.

[GasGuzzler]

Most times they'll set P0101 MAF and P0171/174 lean both banks when the intake is leaking vacuum.

[CoupeDevilln]

I did check for intake leaks. I replaced the fuel filter, no change. I checked fuel pressure, it was at 53psi at idle while it was misfiring.

And intake temp seemed pretty constant across the intake, so no broken valve spring.

I was told that O2 sensors can malfunction, leaning out the engine without setting a code. Anyone heard of this.

[GasGuzzler]

It's possible if they are reporting to the PCM proper mixture when the mixture is wrong it would run bad and set no O2 codes....but would set something, misfire, etc.

You need a scan.

[RedHeartbeat]

Start by cleaning your MAF sensor, especially if you're running an oiled filter such as the K&N filter. From there pull the fuel pressure regulator vacuum signal line from the regulator and start the engine and watch for fuel leaks at the port on the regulator. Check fuel pressure 50-60 psi at idle and expect about a 6 psi boost in pressure when the vacuum line is removed. Finally, I would check the 02 sensors. Find someone with HPTuners and have them scan your O2 readings, force it into closed loop and see if the engine loads up. If one side of the readings are sluggish or significantly different than the other you have an O2 issue.

[conekiller01]

Had a buddy last week go through a very similar sounding situation. kept coming back with random misfire codes and oxygen sensor codes so changed plugs wires and cat. . .same problem! first shop told us the engine lost lost compression and needed replacing then a customer out front told us to pull off the plug wires off one at a time with the engine running and check for white sparks at the coil packs sure enough number 5 had nothing replaced in 2 minutes and runs like a champ!

[CoupeDevilln]

Start by cleaning your MAF sensor, especially if you're running an oiled filter such as the K&N filter. From there pull the fuel pressure regulator vacuum signal line from the regulator and start the engine and watch for fuel leaks at the port on the regulator. Check fuel pressure 50-60 psi at idle and expect about a 6 psi boost in pressure when the vacuum line is removed. Finally, I would check the 02 sensors. Find someone with HPTuners and have them scan your O2 readings, force it into closed loop and see if the engine loads up. If one side of the readings are sluggish or significantly different than the other you have an O2 issue.

Replaced mass air flow sensor, fuel is at 53psi at idle with the vac line on. I'm having a guy at MC Racing diag it on wensday in trade for polishing. I'll let you guys know.

[CoupeDevilln]

Ok, I noticed that my old plugs were proper color(tan) on the pass side. On the drivers side they were black, rich or not burning fuel. Also tried to replace the O2 sensor on the drivers side in front and back of the cat, no change. Spark off the plug wire is blue, so don't think thats it.