Need help: Sputtering and smoke!!

[OneJay]

Hey everyone. Just joined because my buddy is having some big problems with his truck. He has a 2000 4.0 SOHC with almost 190,000 miles on it. Lately it has been idling really rough and has been dying when any load is put on the engine, and would not rev above 2500rpm. We replaced the front O2 sensor and now it is mildly drivable, but starts to sputter and smoke after a couple of minutes. It looks like the (white) smoke is coming from the catalytic converters, and I think maybe something might have leaked down onto them, but that wouldn't explain the sputtering. Any ideas? We've replaced the O2 sensor and the fuel filter, and could use some suggestions if anyone has any. Thanks!

 

[Dan Whitaker]

Is the CEL lit?

Does the white smoke smell sweet?

 

[OneJay]

CEL is not lit now, but it was before because of the O2 sensor. It said two were bad, and we replaced the front one.
The white smoke smells disgusting. Like burnt plastic or something, so it's not coolant...oh and the smoke is not coming out the exhaust pipe, but off of the cats. Maybe oil or tranny fluid is dripping onto them?

 

[OneJay]

Well, we unplugged the MAF sensor and it ran pretty much the same and did not throw a check engine light until we plugged it back in. It shows a CEL now, but didn't before? Could it have not known it was malfunctioning before, and realizes it now? It seems like the bogging and sputtering could be caused by a faulty MAF....maybe I'll see if I can get a working one for cheap.

 

[nitro71]

I wouldn't just replace the MAF like that.. I'd get the codes pulled. Clear them. Start on basics. Check plugs. Fuel filter. Air filter. You could clean the MAF with some MAF cleaner(available at parts store). How does it run in neutral?

Codes said two 02 sensors were bad so you replaced one? LOL! Quit easter egg hunting! Clear codes. Run it for a bit. Pull codes. See if it tells you to replace the 2nd sensor.

 

[OneJay]

The fuel filter is new, and the air filter only has a couple thousand miles on it. Haven't checked the plugs yet, but plan on it before really looking into the maf. If I can find someone to let me borrow theirs for a try that would be ideal. I cleaned the maf too and it made no difference. We only replaced the upstream O2 sensor because a malfunctioning rear one would not make the car run any differently. They are only there to make sure the cats are still working. We used a bottle of Lucas injector cleaner and it seems to have helped a bit. It idles fine in all gears, but just sputters and stalls when load is put on the engine.

 

[ThePhoenix]

We used a bottle of Lucas injector cleaner and it seems to have helped a bit.

I have another mystery CEL...maybe I will try the lucas stuff. I ran my tank almost empty and am sure I got crud from bottom of tank. changed filter but light is back 200 miles later