I have a 2001 Dodge Dakota sport pickup. 6 cyl. Purchased from private owner. 119,000 miles on it. Does not burn oil, loose oil, no tapping in engine. Truck will not pass inspection because of a code diagnosed as cylinder 4 misfire. When the truck is first started up, it runs rough. After it has been running about 15 minutes or so, no more rough idle and basically purrs like a kitten. The garage that I took it to has replaced the spark plugs, wires, full tuneup. Oxygen sensor was replaced. It still will not pass inspection and the problem continues. When the truck was brought in, the check engine light was not on. It turned out that the cluster was defective and that was replaced as well. A compression test was done on it and the compression was very good. The mechanic didn’t know what else to do or check so I just brought home. Have taken to a dodge dealer and they did a leak down test and claim that it needs a complete valve job but won’t tell me that this will cure the problem. Very expensive and want to know if there is anything else to check before going to this. Sorry for the long winded post.
Possibly a leaky fuel injector on that cylinder? Fairly cheap to try.
As far as I can remember, cylinder misfire can be attributed to three things: bad air/fuel mixture, compression loss, or spark loss. I believe we can rule compression loss out since that was checked. Spark loss is another possibility. We can only partially rule that out since the spark plug has been replaced. It could therefore be an electrical system (ignition) problem. As oblivion said, maybe it’s an air/fuel mixture problem and there’s a problem with a fuel injector, again I would have expected some other code.
I have the feeling the key here is in what you said about the engine warming up and no more rough idle. I tend to believe that means it’s a fuel-air mixture problem as things to expand when heated.
Before we completely rule out the potential that it is a compression loss problem, I have one question. Was the compression checked after the engine was warm or when the engine was cold. I am willing to bet that the compression was checked after the engine was warm for a while. I think it would be worthwhile to leave the car overnight and check the compression after a cold start.
Thanks, will have that checked out. Rather that than a valve job for sure.
The truck wasn’t left overnight so when I have them check out the injectors I will have the truck left overnight and see what comes of it. One thing I didn’t mention which I should have when re-reading my initial post was that the compression test was called a leak down test, if that makes a difference.
Swap out the injector for #4 with another in the bank. If the misfire moves with it, that’s the problem. First I’d try a few tanks of fuel with some upscale injector cleaner.
I don’t think the Mopar system is sophisticated enough to have different pulse widths for individual injectors. #4 may be running lean with the rest running slightly rich. The O2 sensor just reads the average for the bank to set the pulse width.
hi i have a 01 dodge dakata and no of someone else with the same problem did you ever figure out what was causing the misfire reading i have spent thousands of dollars trying to fix it and nothing has worked i gave up and have just been living with it but would love to figure it out i have had several mechanics look at it including dodge just got tired of throwing money away please let me know thanks
A serious question?
My 99 3.9 SLThas been misfiring on #4 cylinder, changed plugs,wires,cap & button, it clears up for I’d say 15 min then goes to sputtering, poping,coughing , it’s in the shop now,I had them replaced cam sensor, crank sensor, all to know avail…they did a compression test on cylinder #4 and it’s got plenty,they are thinking the computer has an issue in it that keeps misfiring on #4 …
That’s $1600.00 for new computer for its az plug and ply only cant run test on it…any other things ya’ll can think of ?
I’d appreciate the positive feedback
They moved the injectors around and continued to misfire only on #4 cylinder not any other when switched around ,? If it had a broken wire it’d misfire on another cylinder you’d think?
Good compression,spark,now the coil? If it was faulty I’d probably not start from experience from the older autos I’ve had