A friend dropped off his 03 1500 with the 4.7 after it started running awful after a restart on a very hot day. This truck has had an exhaust leak on the left side where the header connects to the pipe for quite a while. It sounds like it is not runnning on all cylinders. I have replaced the plugs due to they all had pretty fried center electrodes and the gap on every one of them was way off what was left. No help. It did originally have a P0121 code so I also threw in a TPS after reading some success stories. No help. I would like to check the resistance of the coil packs but I am not sure how to proceed with that or what the proper range is, so I would like help with that. Thanks in advance for any help.

 

does it throw any other codes? my dakota with the 3.7 would idle rough at stopps and stall when it needed a new pcv valve. also migh could check the egr.

 

Since you say 4.7 and "sounds like it is not runnning on all cylinders", pull the valve covers and made sure it did not throw any rocker arms. Some 4.7's have a bad habit of doing so.

Welcome to the board BTW.

 

No other codes so far. But it might not be running long enough to trip any. Will pull the covers this weekend to check the springs and rocker arms.

 

UPDATE - Found both top and bottom bolts at rear of left side exhaust manifold had popped heads and that was the exhaust leak. Fixed that. No help on the running rough problem. We assumed all along that the problem was on the left side. No thrown rocker arms on that side. Finally had it towed to a shop. They found 0 compression in #2 and said it would be $3200 for valve job. Buddy, doesn"t have that so towed it back so we could tackle it. Popped off the right side cover and looky there, 1st rocker arm is laying at the bottom. Put it back on, but it seemed really loose. Put everything back together, ran it. Loud knocking noise now, and still runs like crap. Pulled cover again, the rocker arm is in place and firm. Haven't retested the compression yet, but I am concerned with the loud knocking noise. Rockers are all moving nicely while running, could a valve still be stuck and making causing that noise. I'm ready to pull the head but if there is a chance to avoid it that would be nice.

 

Also just FYI, even though I have had only short run times it still hasn't thrown any codes beyond ones for sensors I have unplugged here and there.

 

Well thanks for the update and glad to hear the fix was simple. Like I said, there are more than a few 4.7's that for whatever reason will throw those rockers. Just keep an eye on them.