I need some help with this 2001 Ram with a 5.2. This customer of mine has had it at another shop and they couldnt figure out the problem. It has also been looked at by us and a trans shop and been verified its not the trans. The truck idles fine and at higher rpm runs fine.During acceleration or if you even put it in first gear and drive at low rpm it spits and sputters almost like a backfire or miss.We have freeze framed every reading imaginable and see no faults in anything. The cat and plugs and wires tps have all been replaced and the truck still does this everytime. Anyone have any ideas what could be causing this?

 

CPS most likely

 

backfire out exhaust or intake? if its exhaust, i would take the pre-cat o2 out and see if it runs better.

 

So we tried disconnecting the pre-cat o2 sensor and driving it and it did not make a difference. I also informed the tech about people having fuel pump issues but the fuel pressure is good and does not change when it starts doing acting up.

 

so it is a backfire out of the exhaust? normally that means its to rich, so its gotta be fuel related more than likely. leaky injectors?

 

Think he meant take the 02 out all together and see if a clogged cat is an issue . Not a bad idea .

Have you done a compression test yet ? Any signs of a head gasket issue ?

Checked timing and fuel sync ?

Checked the plenum gasket ?

Not much else , other than tracing wires or blaming the PCM , I can think of right now .

 

i didn't include it above , but , I was wondering the same .

 

Check your firing order to make sure none of the spark plug wires are mixed up.

 

and yes i meant pull the o2 out of the pipe

 

How many miles on the truck? Any recent changes or work done prior to the backfiring issue? No CEL? Is it backfiring on all cylinders or a select? Also interested in the results of a compression test.