Bogging Out?
12-02-2011, 04:34 PM
#46
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
12-02-2011, 05:47 PM
#48
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Good to go, just like my wife's 88. What output voltage do you have from your CPS?
12-02-2011, 08:43 PM
#50
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Engine: 4.0
Sounds like a coil. They can short internally when hot. Sometimes they'll make a no start condition, sometimes it'll bog. Sound familiar?
When it won't start or is running badly - pull a plug wire at the plug - look at the spark - it should be a thin crispy blue color - not red or yellow.
You checked the spark, but not when it wasn't starting.
The original coils are famous for it - but aftermarket's are worse.
Buy quality, not Chinese knock-offs. NAPA, CarQuest, or the dealer. AutoChina and the like only sells trash.
When it won't start or is running badly - pull a plug wire at the plug - look at the spark - it should be a thin crispy blue color - not red or yellow.
You checked the spark, but not when it wasn't starting.
The original coils are famous for it - but aftermarket's are worse.
Buy quality, not Chinese knock-offs. NAPA, CarQuest, or the dealer. AutoChina and the like only sells trash.
12-02-2011, 08:43 PM
#51
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Year: Several
Model: Cherokee
Engine: 4.0
Sounds like a coil. They can short internally when hot. Sometimes they'll make a no start condition, sometimes it'll bog. Sound familiar?
When it won't start or is running badly - pull a plug wire at the plug - look at the spark - it should be a thin crispy blue color - not red or yellow.
You checked the spark, but not when it wasn't starting.
The original coils are famous for it - but aftermarket's are worse.
Buy quality, not Chinese knock-offs. NAPA, CarQuest, or the dealer. AutoChina and the like only sells trash.
When it won't start or is running badly - pull a plug wire at the plug - look at the spark - it should be a thin crispy blue color - not red or yellow.
You checked the spark, but not when it wasn't starting.
The original coils are famous for it - but aftermarket's are worse.
Buy quality, not Chinese knock-offs. NAPA, CarQuest, or the dealer. AutoChina and the like only sells trash.
12-02-2011, 08:47 PM
#52
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Try this for a suspected coil/ICU issue:
Renix Jeep ICU/Coil contact refreshing
The contacts between the coil and the ICU on your Renix Jeep can become corroded and loose causing a complete or intermittent no-start condition. I recommend the following procedure as a maintenance precaution to insure this is eliminated as a possible cause now and in the future.
The coil is attached to the ICU by two T20 Torx bolts. Remove these two bolts and lift the coil up off the ICU. You will see 2 pins and 2 sets of contacts. Clean both the pins and springy contact pieces with a good electronics cleaner.
Squeeze the springy contacts closer together with some needlenose pliers. Apply some dielectric grease to the contacts and bolt the coil back on to the ICU.
While you’re right there unplug the connectors from the ICU and inspect the pins in the harness connector. Make sure the pins are not retracted into the connector. Spray out the connector and the receptacle of the ICU with the same good electronics cleaner you used earlier. Apply dielectric grease to the connectors and plug them back in.
I feel this procedure should be performed at least once in the lifetime of a Renix Jeep.
Revised 11-29-2011
Renix Jeep ICU/Coil contact refreshing
The contacts between the coil and the ICU on your Renix Jeep can become corroded and loose causing a complete or intermittent no-start condition. I recommend the following procedure as a maintenance precaution to insure this is eliminated as a possible cause now and in the future.
The coil is attached to the ICU by two T20 Torx bolts. Remove these two bolts and lift the coil up off the ICU. You will see 2 pins and 2 sets of contacts. Clean both the pins and springy contact pieces with a good electronics cleaner.
Squeeze the springy contacts closer together with some needlenose pliers. Apply some dielectric grease to the contacts and bolt the coil back on to the ICU.
While you’re right there unplug the connectors from the ICU and inspect the pins in the harness connector. Make sure the pins are not retracted into the connector. Spray out the connector and the receptacle of the ICU with the same good electronics cleaner you used earlier. Apply dielectric grease to the connectors and plug them back in.
I feel this procedure should be performed at least once in the lifetime of a Renix Jeep.
Revised 11-29-2011
12-02-2011, 10:44 PM
#53
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Year: 1996
Model: Cherokee
Engine: 1998 4.0L Inline 6
Sounds like a coil. They can short internally when hot. Sometimes they'll make a no start condition, sometimes it'll bog. Sound familiar?
When it won't start or is running badly - pull a plug wire at the plug - look at the spark - it should be a thin crispy blue color - not red or yellow.
You checked the spark, but not when it wasn't starting.
The original coils are famous for it - but aftermarket's are worse.
Buy quality, not Chinese knock-offs. NAPA, CarQuest, or the dealer. AutoChina and the like only sells trash.
When it won't start or is running badly - pull a plug wire at the plug - look at the spark - it should be a thin crispy blue color - not red or yellow.
You checked the spark, but not when it wasn't starting.
The original coils are famous for it - but aftermarket's are worse.
Buy quality, not Chinese knock-offs. NAPA, CarQuest, or the dealer. AutoChina and the like only sells trash.
12-03-2011, 12:10 AM
#58
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Year: Several
Model: Cherokee
Engine: 4.0
Think!
Why after so many years and so many miles would it suddenly need the injectors to be wrapped?
Why don't the other millions of 4.0's need it? Why just yours?
When you checked the spark what color was it? How far did it jump? You don't need to test it on all the plugs, at the distributor end of the coil wire is good enough. Color and how far DOES make a difference.
Did it start right after you tested it? When you tested it it may have already gone back to normal.
Swap the coil wire out - another possible.
A leaky injector won't stop it from running - it may misfire, overheat the cat, smell funny, but it will run - the other cylinders still work.
Why after so many years and so many miles would it suddenly need the injectors to be wrapped?
Why don't the other millions of 4.0's need it? Why just yours?
When you checked the spark what color was it? How far did it jump? You don't need to test it on all the plugs, at the distributor end of the coil wire is good enough. Color and how far DOES make a difference.
Did it start right after you tested it? When you tested it it may have already gone back to normal.
Swap the coil wire out - another possible.
A leaky injector won't stop it from running - it may misfire, overheat the cat, smell funny, but it will run - the other cylinders still work.
Last edited by rrich; 12-03-2011 at 12:14 AM.
12-03-2011, 08:53 AM
#60
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0