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  #1  
Old May 13th, 2017, 20:35
1989AMCXJ 1989AMCXJ is offline
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89 XJ Warm Engine/No Start

I have read countless articles on this issue, and I have found zero solutions. Any guidance here would be gratefully appreciated. OK, Starts cold no problem, drive it up to normal operating temperature, park it for 25 minutes or more, No start, just crank...Let it sit for hours, until cold again, starts.

Engine: Renix L6 4.0 with Cam, Polished ported head, bored out throttle body to HO specs, TB spacer, pacesetter headers.

Fuel New: Fuel Pump assy and pump, hoses, FPR, 3rd Gen Bosch four hole injectors, Insulation on manifold, fuel rail and injectors. Fuel Pressure 35lbs. Air fuel gauge reads Ideal to sometimes rich condition.

Sensors: ALL NEW including CPS. (tried to purchase better quality parts, not cheapy ebay china crap.)
Also Running the "R.E.M.+ V3" (hooked directly to the ECM port) and all diagnostics are within factory specs and no error codes out of range (Pre-OBD).

Ignition: Yellow top Bat good, Bosch High output Alt. Good, Cap, Rotor, Distributer (1 year old), Plugs, wires (1 year old), Coil, Coil Module, Starter relay switch, all other relays(4)(1 month old).

Grounding: Extra #4Cu gnd from rear of engine to Firewall and from bat gnd mount on block to second location on firewall, and from bat to gnd on front of frame.
(Positive cable from bat to starter good)

CPS Testing Results:

Cold Engine
Testing: CPS plug (Wiring harness end ignition on): 3.4V
CPS Resistance: 232
CPS AC V Spike when cranking: 0

Drove XJ, all warmed up, no issues. 180F
20 minute wait, test then crank: started up no issues

Engine Warmed up
Testing:
CPS plug (Wiring harness end ignition on): 3.4V
CPS Resistance: 278-280
CPS AC V Spike when cranking: 0

20 Minute wait, crank: started up no issues 160F
25 more Minutes wait, crank: 140F no start
CPS ohms test on harness side: 9.36
5 minutes later, started right up

Drove 10 miles, parked, came back hour later, no start, than I tried open throttle, started right up...
I am losing my mind!!!
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  #2  
Old May 13th, 2017, 20:39
blakews2217 blakews2217 is offline
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89 XJ Warm Engine/No Start

Other than the CPS resistance change is there moisture in the dist. Cap?


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  #3  
Old May 13th, 2017, 20:58
1989AMCXJ 1989AMCXJ is offline
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Re: 89 XJ Warm Engine/No Start

Negative
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Old May 13th, 2017, 22:19
blakews2217 blakews2217 is offline
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89 XJ Warm Engine/No Start

Can you verify if it's no spark when it won't start? Also, check it the wiring harness where the fuel rail would usuly want to wear through it.


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  #5  
Old May 15th, 2017, 07:57
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cruiser54 cruiser54 is offline
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Re: 89 XJ Warm Engine/No Start

3.4 is borderline AC voltage output from a Renix CPS.

check this out:

http://cruiser54.com/?p=50

Also Tip 3 on the same website.
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Old May 15th, 2017, 12:34
1989AMCXJ 1989AMCXJ is offline
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Re: 89 XJ Warm Engine/No Start

OK , wiring harness looks ok. This is the 3rd CPS I've replaced in six months... All diff brands...I'll re check spark after warm up soon...been a bit busy...
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Old May 15th, 2017, 12:36
1989AMCXJ 1989AMCXJ is offline
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Re: 89 XJ Warm Engine/No Start

Quote:
Originally Posted by cruiser54 View Post
3.4 is borderline AC voltage output from a Renix CPS.

check this out:

http://cruiser54.com/?p=50

Also Tip 3 on the same website.
"Oh and thanks...I live on this website"
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  #8  
Old May 15th, 2017, 12:38
1989AMCXJ 1989AMCXJ is offline
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Re: 89 XJ Warm Engine/No Start

Quote:
Originally Posted by cruiser54 View Post
3.4 is borderline AC voltage output from a Renix CPS.

check this out:

http://cruiser54.com/?p=50

Also Tip 3 on the same website.
This reading is from the Harness Side to the CPS
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  #9  
Old May 15th, 2017, 14:00
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cruiser54 cruiser54 is offline
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Re: 89 XJ Warm Engine/No Start

Quote:
Originally Posted by 1989AMCXJ View Post
This reading is from the Harness Side to the CPS
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
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Old May 15th, 2017, 18:34
1989AMCXJ 1989AMCXJ is offline
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Re: 89 XJ Warm Engine/No Start

Quote:
Originally Posted by cruiser54 View Post
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
Hooked up voltmeter, set to AC to CPS harness connector, cranked, Reading was 000
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Old May 15th, 2017, 18:35
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cruiser54 cruiser54 is offline
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Re: 89 XJ Warm Engine/No Start

Quote:
Originally Posted by 1989AMCXJ View Post
Hooked up voltmeter, set to AC to CPS harness connector, cranked, Reading was 000
Not good. ever done the drill mod?
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  #12  
Old May 15th, 2017, 19:20
1989AMCXJ 1989AMCXJ is offline
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89 XJ Warm Engine/No Start

Quote:
Originally Posted by cruiser54 View Post
Not good. ever done the drill mod?


The six page mod that used to have a harness kit? To run the two wires direct to the ECU?


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  #13  
Old May 15th, 2017, 20:30
1989AMCXJ 1989AMCXJ is offline
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89 XJ Warm Engine/No Start

Quote:
Originally Posted by 1989AMCXJ View Post
The six page mod that used to have a harness kit? To run the two wires direct to the ECU?


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Or is it drilling out the holes to put the magnet closer to the flywheel...


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  #14  
Old May 15th, 2017, 23:54
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cruiser54 cruiser54 is offline
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Re: 89 XJ Warm Engine/No Start

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Originally Posted by 1989AMCXJ View Post
Or is it drilling out the holes to put the magnet closer to the flywheel...


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Drilling the upper hole per the instructions on my website.
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  #15  
Old May 16th, 2017, 06:49
1989AMCXJ 1989AMCXJ is offline
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89 XJ Warm Engine/No Start

Ok, so with no signal coming out of the harness side, how does that reflect making a mod in the CPS side? The harness side has no signal from the ECU, so wouldn't you repair that?


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