First off, I own a 2003 Ram 2500 Hemi with a 5 spd. It curently has 54K miles.

A couple months ago, I was driving to work and I heard a pop and then a loud hissing; it sounded like the bleeder valve on an air compressor. I thought that It was my headgaskets. So I replaced them as well as all the top end gaskets. I reinstalled everything the specs. Torque and all. When I tried to start it, it took me a about a day for it to turn over and fire. When it finally did, it was acting like it was misfiring and turning at about 400 rpms and whenever I gave it gas it would raise rpms but not by much. So I checked the coil packs with a multimeter and they are all good. The plugs looked good but I replaced them anyway with the factory Champion Copper plugs. The resistance in the wires is good so I haven't replaced them yet but I seriously thinking about it.

Anyways after I changed my plugs and tried to start it again, all it does is turn over and start, then backfire and die. It went from bad to worse just by replacing my plugs. My mech told me to try and recalibrate the TPS switch so I did. And still the same thing is happening. I am at my witz end and quite frankly pretty piterrbed. Anybody have any ideas.

 

did you reset the pcm? might be that simple.

 

How do you reset the PCM?? I have never that before.

 

You can pull the PCM fuse, leave it out, then turn the key back and forth 2x without starting the truck, then replace the fuse. But I dont think that is it. Thats sounds like more than a PCM reset to me. Pull the valve covers and check the springs to make sure none are broke and that everything is lifting as it should. You can also do a compression check on each cylinder to make sure of the same.

But you said you changed the head gaskets right? did you notice anything of the springs then? Did you rotate the engine by hand (breaker bar on crank bolt) to make sure the push rods and all were seated good? Last thing I can think of would be timing chain.

 

When I changed the headgaskets I did check everything. spings, valves, retainers and valve seals. They appeared to be alright but once the heads were back on I did not rotate the engine. When I torqued the rocker shafts down(and believe me that was fun) eveything went together beautifully. I am pretty sure the Rods are seated correctly.

 

Did you actually find a failed head gasket ?
I would do a compression check now before you go any further.

 

We had a guy on the other board that couldnt get his engine to run right after putting in a cam I think. It took him a while to figure out one pf his pushrods didnt seat good and popped out of place during the rotation of the engine. Do a compression check or pull the VC's and make sure. Like I said, if no CELs or codes, the only other thing I can think of is the timing chain.

 

Thanks fellas. I will check out my heads and check compression when I get a chance this week. If nothing turns up, I guess it is off to a shop. I hate doing that. But thanks none the less.

 

This sounds very odd to me. Was it a vacum leak or pressure. Was it a continious hissing? Did it ever stop hissing? Radiator overheat? If was pressure, could you have a collapsed muffler or cat? If the exhaust is blocked the engine won't run at higher rpm. Compression tests will give you good information what is going on with the engine.
Good luck

 

So I removed my valve covers and rotated the motor. Everything was working perfectly. I doublechecked all my springs and rockers. I tryed to start it again and it was still running low rpm. I have no clue.