Fastcar302

That was a good article. I have some of the same symptoms, but no popping or misfiring. I'm going to pull the exhaust after work today and see if it makes a difference. I have a sneaking suspicion my cat(s) are bad. I'll definitely post my findings either way.

Fastcar302

Well, I disconnected the exhaust from the manifolds last night and there was no difference. It still bogs and will barely move. I'm going to check compression on all cylinders and while the spark plugs are out I'm going to look for soot to possibly identify a stuck open injector. I'll keep you guys posted.

Fastcar302

I unplugged the MAF and though it wouldn't idle very well, it didn't bog under acceleration and pulled pretty good. So I bought a new one and installed it. Same damn symptoms.Since it did run good with it disconnected, that would eliminate compression problems, bad valves, CMCV problems, and stuck injectors since the motor is actually capable of revving up and producing power. Something is telling the computer that the motor is running rich, when in fact I don't think it really is, and therefore when the ECM pulls out fuel it actually becomes lean. At least that's my theory anyway. I am fresh out of ideas at this point. Anybody?

VTX1800N1

This may be a stupid question, buy you did do the PCM reprogramming as part of the cam phaser lockout install, right?

Fastcar302

Yes, I used a custom tune from a local reputable shop via SCT X4.

Summers22

iTrader: (2)

You did a visual inspection of the FPDM? Removed it and looked at it? Also how many miles on the truck? O2 sensors should be replaced every 75k to work effectively.

VTX1800N1

At some point you should have installed a tune from Livernois for the lockouts. I think you can piggyback a performance tune on top of their lockout tune, but you need their tune to tell the computer that the phasers are locked.

Fastcar302

The custom tune I have is for the lockouts. I didn't get the programmer from Livernois because it only allows for the ECM to turn off the VCT and won't allow you to change anything else, plus it's way more expensive than the SCT. The Livernois programmer is definitely not the best bang for your buck.

Fastcar302

No, I didn't inspect the FPDM because I can see on my scanner that the fuel pressure stays at around 40 psi. If it was dropping off or something like that, then I would check it, but the data doesn't suggest that there's a fuel pressure problem. The truck has 170k miles and I've never replaced the O2's, but I've only owned the truck for a year. So it's not to say that they haven't been replaced before. I looked at the graph from both upstream O2's on my scanner and they were producing similar sin wave pattern graphs which doesn't lead me to believe they are faulty. I've already spent a lot of money on this truck at this point so I don't want to just start replacing stuff unnecessarily. If something is bad I'll replace it, if not I'll let it ride.

lewissa81

Just because the O2's are "working," doesn't mean they are working well. When they get older, they can get lazy and not detect a change in a/f ratio as quick. This means the pcm is receiving old information. Keep in mind we're dealing with tenths and hundredths of a second. You need some pretty expensive scan tools to measure that type of delay.
I'm not trying to say I definitely think your issue is your O2's, but I would replace them anyway. Then again, I would check the condition of the FPDM no matter what the pressure is because it's free, and good to know before the part fails.