Truck stumbled, then OK....

[redrider#1]

It happenned going up a long fairly steep hill pulling about 11k total, engine stumbled just a tad as I was lugging it at 70mph just before a downshift.

Then, LOUD clattering and engine lost power as a backfire and large puff of white smoke---this lasted for about 3 or 4 sec, I let off pedal and then power came back and engine never died (never had to restart)

EGT--1000, coolant---195

No SES, but haven't checked for codes yet.
Truck ran fine the rest of the trip.

Fuel filter and air filter changed less than 2k miles ago.

One more thing, I swiss-cheesed the air box and this is the first time I have pulled since. Could possibly higher intake temps due to engine heat cause something like this?

Any ideas?

[mark45678]

sounds like turbo BARK? My lly with juice would do this about 20% of the time on upshifts if was making high boost just as it backs off to shift I would feel it fall flat and POP in the intake as all the boost in the IC spun the turbo backwards for a second. It never hurt anything in the 80,000 miles I owned it !( 70000 of those mile juice set on 3)

[redrider#1]

I have noticed the turbo bark every now and then now that I have the Juice W/A and it happens when the turbo is spooled up and then I let off the gas abrutly and rpm's fall quickly, but that didn't happen this time.

I wonder if the engine was sucking a lot of fuel for some reason (new air box mods and juice on level 2) as I was lugging the engine (again, more fuel needed) so it simply lost power when the fuel supply couldn't keep up with the demand.....Does this sound right? I tend to think this is what happened based on the fact that the engine didn't die and only hesitated for 3-4 sec. But would a lean condition cause the puff of white smoke I saw?

[Mark Rinker]

If you pull codes, I bet you find an overboost code that caused the ECM to defuel, causing the series of events you describe.

White smoke would be oil smoke. I'd say the sudden defuel caused oil to get sucked past a seal momentarily. My '98 did this once when defueling, caused by a roadsalt restricted OEM air filter. Very weird sound and the smoke makes you think you tossed a rod or something. Unnerving to say the least!!!

Personally, I'd now cover your 'swiss-cheezed' air holes with tape and see if it happens again. I have run my '01 on some healthly Predator settings with equally healthy doses of propane, but never barked the turbo, even under heavy foot and heavy load conditions. The worst I have done is limp mode from tranny slip and some overboost condition codes. Both are controllable by turning things down, especially when towing heavy.

[redrider#1]

Ok here are the codes that I pulled.....

P0101------mass air flow sensor performance

P0341------camshaft position sensor performance

So.....what do they mean? I can possibly understand the MAF code due to the air box mod, and that can easily be fixed, BUT the camshaft code makes me a little nervous. Maybe someone who has more experience in this area can chime in?