Does this sound possible?

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09-27-2009, 02:25 PM
yournamehere018

Does this sound possible?

When I first start up and try to drive home the truck will bog down so bad it will hardly move and backfire like crazy, part throttle or floored or anywhere in between. After a few minutes though it gets a little better. Also, the high end (4,000 and up) pulls pretty hard but the low end is hardly ever there.
About the only time I have low end is after a highway ride, right after. I checked the fuel system, it gets 55-65 psi, gutted the cats and removed the EGR (and had Virgil tune for it), replaced everything ignition, replaced intake gaskets, and checked the coolant temp sensor. No improvement. As I was watching the oil pressure gauge, I noticed that it seems to do better while the oil pressure is up. Could it be bad lifters maybe? I dont know much about them but I do know they are supposed to pump up.

The truck has ~140,000 miles. Running Mobil 1 and a quart of Lucas. V says the front O2 sensors max out under full throttle but not sure why.
09-27-2009, 02:37 PM
RedHeartbeat

you need a wideband in there to see what its really doing. Mine was running like crap a few weeks ago so I hooked the WB up and found that the driver side 02 sensor was bad. fixed it and no more problem. I have dual WB sensors so that I can tell whats wrong from one side of the engine to the other. :thumb: If you have dual ports already welded in your exhuast then you could drive up here and we could check it out. I can read your narrowband sensors using the HPTuners but its not quite as accurate.
09-27-2009, 02:41 PM
yournamehere018

The rear O2s are turned off so I guess either of those ports would work. This thing is driving me crazy trying to find the problem. I replaced the passenger side front sensor for the hell of it, no change.
09-27-2009, 02:44 PM
RedHeartbeat

did you try taking the one you took out and placing it in the drivers side? Also, try cleaning the MAF sensor with the proper spray cleaner.
09-27-2009, 02:51 PM
yournamehere018

I haven't tried it yet, I will though. It's so low that it takes quite a bit of work just to get a floor jack under it to do the easy things. I think I cleaned the MAF with MAF cleaner but I will try again tonight at work just in case. Do you have to use credits to log with HP tuners?
09-27-2009, 02:57 PM
RedHeartbeat

nope, only to make changes to the tune
09-27-2009, 03:37 PM
yournamehere018

Cool. I may come up there some time then if I can't find out what it is.
09-28-2009, 08:31 PM
txarkitekt

Quote:

Originally Posted by yournamehere018

...gutted the cats and removed the EGR.

Were the cats gutted correctly? Have you checked the fuel filter? FPR?
What is your fuel pressure under load?
10-04-2009, 12:31 AM
yournamehere018

Yeah I cut the y pipe, hollowed the cats and ran pipe through them, then rewelded. Fuel pressure was fine.

Solved!
It was the MAF. I could have sworn I cleaned it, must have been the other truck though because that thing was absolutely filthy. Solid black. Thank you guys so much.