I own a 1994 dodge ram 1500 with a 5.2L. When i first crank the truck on a cold engine it has a hard time cranking. After it cranks it idols fine but applying throttle causes the truck to bog down (almost stall) and make loud popping noises. I've found that tapping the gas a couple time then actually trying to go will allow me to get moving/speed up. This problem seems to have a mind of it's own because every time i change anything electrical (plugs, wires, sensors, ect) the problem goes away and then returns the next time i crank it when its cold.

Here is the list of everything i have tried so far:

1. New spark plugs
2. New spark plug wires
3. New rotor and distributer cap
4. New EGR valve (this was stuck open and the new one helped the problem a little)
5. Seafoam in gas, vacuum lines, and oil
6. Decarbonized at dealership
7. Compression test-all cylinders were in the normal range (#2 was slightly low)
8. Removed and cleaned injectors
9. Replaced injector seals
10. Checked all fuses and relays were clean and had contact
11. New fuel pump
12. New oil pump, oil sending unit, and cleaned small amount of sludge from bottom of oil pan for ?unrelated? problem. (oil sending unit stopped working and oil pressure would drop to zero when idoling)
13. Removed and cleaned the throttle body
14. New IAC valve (was sprung and the new one also helped the problem a little)
15. Checked for vacuum leaks. none found
16. Removed O2 sensor on the cat to check if it was clogged. Ran worse.
17. Replaced O2 sensor on the cat (ran perfect until the engine cooled and recranked)

This is probably unrelated but the coolant temp sensor when out. Replaced it and it went out again a week later, so the temp just reads 0 degrees.

I'm thinking that i need to reflash the PCM or maybe its a plenum problem (170k miles and never been changed as far as i know). The cat could also be clogged (testing it tomorrow by drilling holes and using a pressure gauge). Any other ideas?

 

Just a quick thought, but do you have plug wires running the proper way as per the issued TSB?? I've heard of problems, when just ran next to eachother from the cap to the plugs.

I once, damaged a wire during a plug swap, and then towed a camper about 300 miles. Everytime, I went up a hill, and hit the throttle hard, it'd start popping like that. Changed the wire and problem fixed.

Your list of fixes is pretty thorough, so someone else will have to chime in on this one. Did you reset the PCM after all the sensor swaps??

 

I printed out the wiring diagram and checked the plug wires. They were all correct. I just reset the electrical system today after i changed the O2 sensor by pulling the negative terminal and turning the key for 30 seconds.

 

https://dodgeforum.com/forum/2nd-gen...lug-wires.html

That's the link to the TSB. Read through that, just wondering if you ran the wires that way, cause apparently it makes a difference. I'm just taking a shot in the dark though. It made a bit of difference on my truck, before I knew about the TSB

 

I'll try that tomorrow. Thanks

 

Spark plug wires are correct. Anyone else have an idea?

 

Well have you checked the plenum? That's where I'd start before anything. Or check for internal vacuum leaks with a gauge.

 

Clogged cat ? Heads could be cracked , heads on our trucks are prone to it

 

Does your truck have one coolant temp sensor or two? Some year models had one to send a signal to the gauge and one to send a signal to the PCM. Some year models had one sensor that sent the signal to both the PCM and the gauge. If yours has the single sensor, and its faulty, that might have an effect on the idle. Might not be the problem, just a thought.

 

94, so he has two sensors. ECT for PCM could be faulty..... (the two-wire sensor.)