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View Full Version : Jeep backfiring/misfiring (under hood, not exhaust), vibes



BlingblingWJBoy
10-21-2004, 01:46 PM
Last year around this time, I had an injector give out. Had it replaced by the shop, and apparently it also fried my Mopar ECU. Put the stock one back in.

Ever since then, I've had these pops that come up really fast, and it isn't a backfire from the exhaust. Comes from under the hood. Usually it's a couple pops in a row, varying in rhythm. Very quick loss of power I think when it pops, but so fast that you can't really tell. I can feel the pop in the gas pedal too. It only does it upon acceleration under load, I can't duplicate the problem in park or neutral. I've also noticed that if I rev it, in between 1.5k-3k RPMs, there's a slight vibration. The vibration is most noticeable when I'm locked in the torque convertor in OD, and trying to accelerate. Entire jeep will start shaking.

I've replaced plugs, wires, cap, and rotor. Didn't seem to help the problem. I don't want to give it to a shop, but I'm running out of options. I kicked the cat convertor but I don't think it's rattling.

What should I do?

OverkillZJ
10-22-2004, 12:08 AM
Beats me...

But... Anyone have any input on a bad injector frying a performance ECU? Are you sure it was fried, or did the shop tell you it was fried... :?:

BlingblingWJBoy
10-22-2004, 01:33 AM
Beats me...

But... Anyone have any input on a bad injector frying a performance ECU? Are you sure it was fried, or did the shop tell you it was fried... :?:

Shop told me it was fried. I didn't have time to tool with it, or else I'd have stuck it back in to see if it worked. I did open that thing up though, and I remember readin that if the substance stuff inside turns brownish, then it's done? Whatever it was, it matched up.. so I thought it was gone.

JeepinHank
10-22-2004, 11:49 AM
Cracked exhaust manifold?

That would explain the exhaust popping under the hood, and why it only does it in gear (torque causing the engine/exhaust system to move and making the crack open up)

Just a possibility...

BlingblingWJBoy
12-12-2004, 05:11 PM
Fixed it. Ran it to a shop, and the computer said #6 and #4 weren't firing correctly. Replaced #6, and found out it was the wrong one to begin with. #4 I haven't done. Backfiring seems to be gone, I've got better power, but there's still some vibrations. Just thought I'd post an update.