1989 Jeep Cherokee Jeep Misfire under electrical load

SPECOPS03

MEMBER
1989 JEEP CHEROKEE
6 CYL
4WD
AUTOMATIC
200,000 MILES

I am having issue where the engine misfires when applying an electrical load such as turning on headlights and triggering the High beams or the combination of rear defogger and lights. Especially bad when putting the vehicle into the Drive position only. Voltage from the alternator is between 14.47V to 13.39V constant. No vacuum leaks are present and the ignition parts: spark plugs, cap, rotor, & wires are new. Could this be still related to the output of the alternator in amperage vice voltage or maybe an ignition coil on its way out?

Monday, February 8th, 2010 AT 3:26 PM

1 Reply

JDL

MECHANIC
16,098 POSTS

Hi, Are you carbed or fuel injected? The reason I ask, if your fuel injected, according to my info, makes it harder to check for mil trouble codes.

Do you have a digital multimeter, most will give inductive reading, by touching the plug wire. You don't unplug anything, you don't penetrate the insulation. You just touch the meter lead to plug wire. Say, if 4 four of the plug wires read.5 volts or close to the same, and 2 are reading zero, you found the place to start. Not conclusive test, but, a place to start.

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Monday, February 8th, 2010 AT 3:50 PM