runs great cold but when warm it runs bad. -

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post #1 of 5 Old 06-23-2011, 08:38 PM Thread Starter
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1999 XJ Cherokee 
Join Date: Jun 2011
Location: Elkhorn City
Posts: 3
runs great cold but when warm it runs bad.

my jeep runs great when cold but when up to operating temp it runs like crap, i checked the fuel pressure its good, no vaccum leaks, i can hook it up on a OTC Genysis it will show a ingnition coil #1 and #2 but i cleared it didn't come back on . I can watch it with the genysis when idling or driving no misfires on any cylinders. Could it be the ingnition coil bar?

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post #2 of 5 Old 06-23-2011, 09:08 PM
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1995 XJ Cherokee 
Join Date: Feb 2008
Location: north Ga.
Posts: 14,216
It could be that it is suffering from heat soak which is common for a failing electrical component. Once it gets to a certain temp it doesn't work correctly but functions fine when cool.

  1. '95 XJ country edition, 4" coils/3/4" spacers, HD leafs with extra main added in, Ironman adjustable control arms, rough country shackles, aussie locker, JK rubicon shocks, 35" mudder's, soft 8's, cobra cb
  2. Sold'99 WJ limited, 4.7L, 3" IRO lift. Bilstein shocks, JK rubicon wheels, 255/70/17's, carolina driveshaft, IRO adjustable control arms, IRO adjustable A-arm
  3. Sold '00 TJ, 4" lift, rusty's adjustable control arms, skyjacker shocks, rock krawler adj. trac-bar,rugged ridge SYE and RE driveshaft, soft 8's, 35" mud king xt's,XJ HP D30 w/aussie locker, 4:88 yukon gears, hella 500's, rock crusher diff covers
4. 04 Dodge ram 1500 quadcab, yes, it has a hemi.
5. '08 BMW X3, Mods in progress.
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post #3 of 5 Old 06-24-2011, 01:21 AM
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1997 ZJ 
Join Date: Dec 2006
Posts: 19,793
Also possible bad o2 sensor. Fuel trims running stupid rich or lean?

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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post #4 of 5 Old 07-06-2011, 03:43 PM Thread Starter
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1999 XJ Cherokee 
Join Date: Jun 2011
Location: Elkhorn City
Posts: 3
the 99 only has one oxygen sensor i cut the catalatic converter off no change. replaced the camshaft position sensor no change, I replaced the ingnition coil bar no change.
It is showing p0351 and p0352 ingnition coil A and B circuit malfunction.
I broke into the harness traced the wires to the pcm nothing broken.
Ive had ppl tell me it is the pcm.
What do u all think?
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post #5 of 5 Old 07-09-2011, 05:29 PM Thread Starter
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1999 XJ Cherokee 
Join Date: Jun 2011
Location: Elkhorn City
Posts: 3
i put a pcm in it no change..
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