Tested on a replacement PCM, no dice. But I can swap it again to see if there's a change.
Random Misfire, No Codes
- Thread starter Mercury
- Start date
Tested on a replacement PCM, no dice. But I can swap it again to see if there's a change.
If you're certain the alternative PCM was a know good unit then the only thing left can be a wiring issue.
I'd still strongly suggest having @Wranglerfix test your PCM.
-Mac
It was an eBay order, bought it when I was chasing the O2 sensor issue. At least if I send him one I'll still have the other to run on
I replaced the throttle body again, this time replacing the TPS as well, now it's running normally other than the miss.
I had my fuel injectors cleaned on one of those injector rigs. They all sprayed well, just a little build up, didn't fix the miss. Only odd thing: one of the injectors had a slightly higher output. At 40 seconds of high-level spray all of the injectors but one were at 80 ml, the oddball was at 86. That injector has a sticker on it that the others do not (though it's identical otherwise), so I wonder if that was a replacement.
Could that be enough to cause a small miss?
I had my fuel injectors cleaned on one of those injector rigs. They all sprayed well, just a little build up, didn't fix the miss. Only odd thing: one of the injectors had a slightly higher output. At 40 seconds of high-level spray all of the injectors but one were at 80 ml, the oddball was at 86. That injector has a sticker on it that the others do not (though it's identical otherwise), so I wonder if that was a replacement.
Could that be enough to cause a small miss?
That cylinder would be slightly rich but well within tolerances.
No individual monitoring of cylinders...you'd need a wide band sensor on each header pipe... racecar stuff.
Nonetheless I paid for a balanced set of rebuilt factory Siemens injectors because I could and it wasn't much more and it's one less thing I have to worry about.
I'd just pay attention to the spark plug on the offending cylinder. If it's black and sticky and the others are tan then you've convinced me of a problem.
-Mac
The spark plugs were in good shape when I changed them recently, but I'll pull it in a week and see if anything is there.
At this point I'm considering an oscilloscope and testing every electrical thing under the hood. I'm starting to wonder if there's something up with the harness at the throttle body. When I switched the TB the first time my O2 sensor codes came back so I swapped it back. I put it back in the other day (vacuum leak was too bad) and it's working fine, though this time I swapped the TPS as well and it's working better. I don't know if a TPS can trigger an O2 code, but if not I wonder about the harness.
I just replace all my dump trailer brakes and bearings. Chasing an issue where it wasn't helping out my truck much stopping. Pounded out all the old races, packed inner and outer bearings...covered head to foot in grease. Wired up the new brakes... electric... passenger side was dead. Driver side is connected directly to a j box that goes to the pigtail to the vehicle... passenger side has a wire that runs through the hollow axle tube... checked continuity on BOTH axles and BOTH pairs of wires had zero conductivity. But I was able to use them as fish tape to get the bad ones out...so zero physical break in the wire or insulation. Both wire pairs were soaking wet...so I drilled holes in the bottom passenger and driver side of both axles...they crown in the center...and drained out a lot of water.
Point of this story is it's probably the wiring and it probably visually looks great...but like my dump trailer it just didn't work any longer.
-Mac
P.S. remind me not to go mudding with my dump trailer.
Point of this story is it's probably the wiring and it probably visually looks great...but like my dump trailer it just didn't work any longer.
-Mac
P.S. remind me not to go mudding with my dump trailer.
That is crazy! These electrical problems are such a hassle.
I think my cheapie TPS gave up the ghost. Idles high, but when I press the gas it bogs and dies. I'll be ordering a Mopar one here shortly.
That's the worst of "cheap" parts...you replaced it and now have mentally ruled and t out as the cause of the problem...but a lot of times that new part is far worse than the original.
Makes troubleshooting a nightmare.
-Mac