2001 Ram 1500, 5.2, 4wd, auto, single exhaust, laramie longbed. dana 60/70, 4.88s.

If I fire it up cold and run an errand, its a fact that after 7 minutes the truck will suddenly lose power/ makes a pinging/clunking/mild backfire sound like its misfiring; I have to back off the gas only for about 30-45 seconds... then it clears up and I can continue on my merry way without any further issues. Never has any idle issues or drivability problems otherwise.

Seems to occur only when driven cold, and since it always happens to occur at a certain point of the road (always going up a mild hill) I'm thinking it has to do with when the engine warms up? I dunno..Once its warmed up, it won't do it for the rest of the day until it cools down overnight.


Have replaced:
-PCV valve
-both O2 sensors
-TPS
-IAC
-CPS (twice)
-coil
-plugs, wires, cap, rotor
-air charge temp sensor


Any suggestions are appreciated.

 

How bout the plenum?

 

The plenum fix!

http://www.hughesengines.com/Index/p...p?partid=27091

 

thanks for the reply. I didn't think the plenum would be suspect, but its about the 1 thing I haven't done yet.

Guess it stops once the engine warms up because as everything heats up it expands and stops any leak?

 

Hhhhmmm..... does ambient temp change anything at all?

 

I had a car that did the same thing. Turned out the fuel filter was almost completely clogged. When cold something with it being in warm up loop helped it run fine. And when I'd go up hill it make the clogged filter get even less fuel...... Might help. Might not but it's a big task to do on just a guess. You can test the fuel pressure at the rail. I beleive it should be 40 psi. I'm not 100% sure on psi. You'll have to wait for someone else to chime in with that. But when I tested my car with a bad filter I still had good pressure. Just bad flow

 

01 should be around 50 psi at idle.

 

Now that you mention it, it does seem to be worse
in cold weather. This past winter in sub 30 degree range it might act up more than once/the stumble lasts longer while driving it. This summer in the upper 90s it hasn't been as bad.

 

Have a look at your coolant temp sensor. If it is questionable at all, just replace it. See if the symptoms disappear.

 

looks like your truck isn't completely stock, considering the axles you have under it, what else has been done to this truck? do you still have the catalytic converter in or strait pipe??