2004 Ram 5.7 Idles Rough?

[darth720]

My sons 2004 5.7 is idling like it has a large cam. It idles rough ,bounces between 400 and 800 rpm and sometimes quits. It runs better over 2000 rpm but still surges a bit. We changed plugs and map sensor. No codes?? Could it be the valve spring horror that I have read about?

[Joe-Dokes]

Hmmm. Could be bad gas, clogged /restricted fuel filter, clogged air filter, Dirty injectors. Also, does his hemi have the cross over wires? If so make sure none of them are grounding out.

Also, what brand plugs did you use? Did you use the ones recommended by the manual. From what I understand, the modern hemi is susceptible to plug gap and heat range.

I'd start with a new fuel filter and a can of injector cleaner and inspect the air filter.

Regards,

Joe Dokes

[cu440da]

Might try a new crank sensor. They're about $10 and a 5 minute install. Mine ran a little rough and threw no codes until it failed completely.

[jamesdart]

first thing i thought when i read the topic, was valve spring. doesnt cost anything to pul lthe valve covers off.

[DODGE]

I change the egr on mine run's great now had same problem as your's

[darth720]

He was driving @ 70 mph on cruise and all was fine, he let off the gas to turn into town and he noticed once the rpm dropped it had poor throttle response and started running rough. The throttle response below 2000 rpm is sluggish but after 2000 it runs better but surges a bit. He filled up with gas the night before so we drained some out it appears to be ok. I filled up my truck the same day and the next day at the same place and put a jerry in the quad,so i am thinking its not the gas.
Its not smoking rich, but the throttle response is sluggish. It idles like its got a big cam, too bad it didnt. LOL
Put 2 cans of injector cleaner in it and its running a little better. Hmm? Got a missfireing code. Going to try the plug wires they run across the engine under the air intake cover. 170,000 km on truck so about 106,000 miles.
Injector problem?

[darth720]

Valve springs OK but no compression on # 1 Cylinder. Leak down test blows air out of exhaust. Burnt exhaust valve.
Why?? Injector lean on that cylinder? Just a bad valve? Any ways both heads are comming off. Ka- Ching..

[Joe-Dokes]

Sorry to hear it wasn't something simple / cheap.

Keep us informed, would like to know how it turns out.

Regards,

Joe Dokes

[dart kid]

Vacuum leak or IAC valve, carbon on the throttle plate would be a good start to check...

Dirty air filter, dirty maf, ect... number of things could cause it.