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Unread 05-02-2007, 09:47 PM   #1
cjist1
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Join Date: Mar 2004
Posts: 136
ignition system trouble on 2.5 L

Im getting this strange electrical misfire while under acceleration, usually only at RPM's higher than 2500. Its not really a misfire like when you have bad wires that are shorting out. Its more severe, like all cylinders are not firing for a split second. I have replaced plugs, wires, cap and rotor. Coil is only 2 years old. Its like a cough or sputter. I also replaced the entire engine wiring harness because the original one was hacked up and shorting out. Im starting to suspect the computer is starting to go bad. Most of the time the speedometer does not work either. It is either on for an entire ignition cycle or off, it never stops or starts in the middle of an ignition cycle. Are these symptoms of a failing ECU?

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92 YJ 2.5L 5 spd.
75.6hp/100.0 ft,lbs.

1998 Grand Cherokee 5.9 Limited
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Unread 05-03-2007, 01:05 AM   #2
YJ_
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1994 YJ Wrangler 
 
Join Date: Dec 2005
Location: Cincinnati, OH
Posts: 344
Quote:
Originally Posted by cjist1
Im getting this strange electrical misfire while under acceleration, usually only at RPM's higher than 2500. Its not really a misfire like when you have bad wires that are shorting out. Its more severe, like all cylinders are not firing for a split second. I have replaced plugs, wires, cap and rotor. Coil is only 2 years old. Its like a cough or sputter. I also replaced the entire engine wiring harness because the original one was hacked up and shorting out. Im starting to suspect the computer is starting to go bad. Most of the time the speedometer does not work either. It is either on for an entire ignition cycle or off, it never stops or starts in the middle of an ignition cycle. Are these symptoms of a failing ECU?

your problems (other than the speedo) sound like a faulty ECU. When mine was on its last leg I would "sputter" while being under throttle. It usually happened on the highway past 40 mph. I don't really know any way to test the computer ( I bought one over the forums, replaced the new (to me) one with my stock one and it's been running fine ever since. This was on a 94 S.
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Unread 05-03-2007, 07:47 PM   #3
cjist1
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Join Date: Mar 2004
Posts: 136
Yeah that sorta sounds like the symptoms Im having. Maybe I will try to find an ECU. Thanks.
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92 YJ 2.5L 5 spd.
75.6hp/100.0 ft,lbs.

1998 Grand Cherokee 5.9 Limited
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