Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: dc on May 17, 2008, 10:05:13 AM

Title: Grand Cherokee heat sensor problem
Post by: dc on May 17, 2008, 10:05:13 AM
Hi
My Jeep runs well but when I stop it will not start until nearly cooled down, indicating a heat sensor problem can you tell me where it is located or whether there might any other problem with it?

Its a 4.0 litre petrol running on LPG 1997 reg

Thanks

DC
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Post by: Jonny Jeep on May 17, 2008, 08:07:29 PM
What year is the Grand? And what engine is in it? More info the better for problems like this. Oh, and welcome to the forum.
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Post by: Bubba on May 17, 2008, 08:57:31 PM
yup hi dood
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Post by: greggmo on May 17, 2008, 10:05:35 PM
hi
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Post by: dc on May 22, 2008, 12:08:16 PM
Quote from: "Jonny Jeep"
What year is the Grand? And what engine is in it? More info the better for problems like this. Oh, and welcome to the forum.


Hi
Thanks for the reply, its a 4.0 litre petrol with LPG conversion and 1997 reg

Dave
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Post by: kitch on May 22, 2008, 12:37:01 PM
do you find that it only does it on a very short jorneys its just that i have a jeep gc lpg and mine does the same only on a very short jorney under a mile
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Post by: dc on May 22, 2008, 12:49:33 PM
Quote from: "kitch"
do you find that it only does it on a very short jorneys its just that i have a jeep gc lpg and mine does the same only on a very short jorney under a mile


The heating guage has to cool to the first bar before it will start, which can happen on a short trip or if you travel 500 miles?
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Post by: Mike Pavelin on May 22, 2008, 02:16:51 PM
That sounds like a problem with the LPG system.
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Post by: Big Stew on May 22, 2008, 08:42:42 PM
Quote from: "Mike Pavelin"
That sounds like a problem with the LPG system.


Sometimes the crank sensors can play up and  only work at certain temps had this on mine ,the AA first blamed the LPG system. Mine would start only when cold and cut out and stop when it reached normal running temp.
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Post by: Jonny Jeep on May 23, 2008, 07:41:26 PM
Crank sensors can be affected by the heat as suggested. It's mounted at the front of the bell housing on the left side of the engine. Another thing that can also be affected by heat is the coil which is bolted to the engine.

The crank sensor is a hall effect sensor similar in nature to ABS tone ring sensors. The coil primary should be 0.95-1.2 Ω The secondary resistance should be 11,300-15,300 Ω.

If you turn your key on-off-on-off-on and leave it on the third time you will get codes displayed in the odometer display. A crank (or cam) sensor may have stored a code (11). 55 means end of codes. Try it, and post any codes displayed.
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Post by: dc on May 25, 2008, 09:58:20 AM
Quote from: "Jonny Jeep"
Crank sensors can be affected by the heat as suggested. It's mounted at the front of the bell housing on the left side of the engine. Another thing that can also be affected by heat is the coil which is bolted to the engine.

The crank sensor is a hall effect sensor similar in nature to ABS tone ring sensors. The coil primary should be 0.95-1.2 Ω The secondary resistance should be 11,300-15,300 Ω.

If you turn your key on-off-on-off-on and leave it on the third time you will get codes displayed in the odometer display. A crank (or cam) sensor may have stored a code (11). 55 means end of codes. Try it, and post any codes displayed.


Hi
Tried the on off but no codes displayed, I guess that must apply to a newer model than my 1997, also tried the ASD relay but no difference and also checked with the LPG guy so I am beginning to think its the coil getting hot and malfunctioning?

Dave
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Post by: MuckShifter on May 25, 2008, 12:12:53 PM
Link is up to 97xj...OBD1 codes..should be same for the Grand?

http://go.jeep-xj.info/HowtoECUcodes.htm (http://go.jeep-xj.info/HowtoECUcodes.htm)
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Post by: dc on May 25, 2008, 07:32:50 PM
Quote from: "MuckShifter"
Link is up to 97xj...OBD1 codes..should be same for the Grand?

http://go.jeep-xj.info/HowtoECUcodes.htm (http://go.jeep-xj.info/HowtoECUcodes.htm)


Tried the code access but no luck with all suggestions?
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Post by: Bubba on May 25, 2008, 08:28:28 PM
sounds like a trip to the stealership to me lpg can fool oxegen sensors so i would imagine it is where the fault lies but there is a possability that its the cam sensor as its a sneaky litle bastard when it plays up so dont rule it out
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Post by: Bishops Finger on May 25, 2008, 10:17:03 PM
Hate LPG.......cheap mileage but more to go wrong....
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Post by: daggie on May 26, 2008, 07:32:30 AM
to get the codes its a dealer job  :wink: on grands
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Post by: dc on May 27, 2008, 08:26:51 PM
Quote from: "Bishops Finger"
Hate LPG.......cheap mileage but more to go wrong....


Don't knock LPG its good stuff, I've had 3 of them and never missed a beat, all that power without the cost of petrol or expensive mechanics on dirty weezels!!!
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Post by: dc on May 27, 2008, 08:28:18 PM
Quote from: "V8 Bubba"
sounds like a trip to the stealership to me lpg can fool oxegen sensors so i would imagine it is where the fault lies but there is a possability that its the cam sensor as its a sneaky litle bastard when it plays up so dont rule it out
Thanks for the replies, I think your right, I'm taking the sensor off tomorrow to get the part number and order one! Thanks