89 xj timing
08-30-2011, 02:00 AM
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89 xj timing
I am working on my 89 xj 4.0 and my timing light says that its retarded 22 degrees. I know that the timing is set by the pcm but i also know that it should not be that retarded. Any help.would be awesome.
08-30-2011, 11:08 AM
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Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Well, if nobody better qualified is going to chime in....that may be correct and as it should be. For emissions the retarded timing at idle may be best. I assume you would have mentioned it if it wasn't advancing with higher RPM.
Older Fiat 124 sport Spider had 2 sets of points, one retarded and one advanced, it switched them with a thermal switch.....
Older Fiat 124 sport Spider had 2 sets of points, one retarded and one advanced, it switched them with a thermal switch.....
08-30-2011, 12:28 PM
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Year: 1990
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Engine: The venerable 4.0
If it runs decent its right. The only thing that will throw the timing off considerably is indexing the distributor wrong. Well, a bad knock sensor will retard it too.... mmmm.
08-30-2011, 01:27 PM
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Ok so i will try it at a higher rpm. But with a bad knock sensor retarding it, it would run hotter. Which would explain my next problem with it always running a little warm and a little bit of backfire when i shift. I have changed it over to an open system cause all i ever did was fight the old closed system and that stupid recovery tank. Thanks for all the help. Keep them coming.
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08-30-2011, 10:08 PM
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See post #5. Slick is pretty slick! By indexing I think he means if it's off a tooth. Somewhere you should be able to find where the rotor should point when the engine is at TDC. Probably a good thing to do first. My knock sensor is above my left ear and works fine. Don't know where yours is!
08-30-2011, 10:38 PM
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Year: 1990
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Originally Posted by DFlintstone
See post #5. Slick is pretty slick! By indexing I think he means if it's off a tooth. Somewhere you should be able to find where the rotor should point when the engine is at TDC. Probably a good thing to do first. My knock sensor is above my left ear and works fine. Don't know where yours is!
09-02-2011, 02:54 PM
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This could be caused by a bad knock sensor. The knock sensors job is to retard the timing when it senses detonation. The factory ones are very fragile.
09-02-2011, 02:58 PM
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Ok i think i will try that. I sure do appreciate the ideas. Do you think that running retarded could cause it to run hotter than normal? Thanks for your help.
09-02-2011, 03:01 PM
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Year: 1990
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Originally Posted by firefighter89
Ok i think i will try that. I sure do appreciate the ideas. Do you think that running retarded could cause it to run hotter than normal? Thanks for your help.