Timing Help? - Page 2 - JeepForum.com
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post #16 of 28 Old 09-21-2015, 01:24 PM Thread Starter
bensimpson1981
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The local dealer told me that it would take them 5 days to get an OEM, that just does not work for me so I plan to buy an aftermarket replacement to get me thought the week, the I'll just replace it again in a week or two with an OEM. Are there aftermarket brands that are better than others?

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post #17 of 28 Old 09-21-2015, 01:41 PM
jonsnw93
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Did you replace the cap and rotor yet
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post #18 of 28 Old 09-21-2015, 02:01 PM Thread Starter
bensimpson1981
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Yes I replaced the cap, rotor and cam sensor inside the distributor. I immediately noticed an increase in ignition strength but still face the same problem it fires for about three seconds then dies. Like the PCM is cutting the fuel. That is what led me to believe that it might be the crank position sensor.
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post #19 of 28 Old 09-21-2015, 04:55 PM
CCKen
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Quote:
Originally Posted by bensimpson1981 View Post
The local dealer told me that it would take them 5 days to get an OEM, that just does not work for me so I plan to buy an aftermarket replacement to get me thought the week, the I'll just replace it again in a week or two with an OEM. Are there aftermarket brands that are better than others?
Get an Echlin from NAPA.
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post #20 of 28 Old 09-21-2015, 05:19 PM
CCKen
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Quote:
Originally Posted by bensimpson1981 View Post
Yes I replaced the cap, rotor and cam sensor inside the distributor. I immediately noticed an increase in ignition strength but still face the same problem it fires for about three seconds then dies. Like the PCM is cutting the fuel. That is what led me to believe that it might be the crank position sensor.
Here's a page from the 2000 FSM (previous years the same) with a narrative about cutting the fuel injection system. It's odd that they would just say "shut down the fuel injection system" when the fuel injectors are powered through the ASD relay, as well and the ignition coil. Why didn't they just say it cuts power to the ASD relay. I can't believe the PCM would just shut down the fuel injector driver circuits.

Of course the PCM has a mind of its own. I found out through my scanner that my PCM calls itself 'HAL', and refers to me as 'Dave'. LOL

Bottom line is the PCM is looking for a signal from the TPS that the crankshaft is rotating. No signal=no run.

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post #21 of 28 Old 09-21-2015, 10:26 PM Thread Starter
bensimpson1981
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Ken and Tim thank you both your input has been invaluable. I think I have isolated the real culprit, the bundle of wires that comes from the PCM to the crank position sensor comes down over the top of the intake manifold before heading down to the crank position sensor. Over time that bundle has gotten brittle and has been melted in the past due to overheating. I believe that through the process of changing intake manifolds I managed to brake the wire that goes to the crank position sensor. Using the new manual, thank you Tim, I am going to do some continuity testing tomorrow to check the integrity of the wires between the PCM and the crank position sensor, there is where I believe I'll find my problem.
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post #22 of 28 Old 09-23-2015, 06:01 AM
CCKen
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Originally Posted by bensimpson1981 View Post
Ken and Tim thank you both your input has been invaluable. I think I have isolated the real culprit, the bundle of wires that comes from the PCM to the crank position sensor comes down over the top of the intake manifold before heading down to the crank position sensor. Over time that bundle has gotten brittle and has been melted in the past due to overheating. I believe that through the process of changing intake manifolds I managed to brake the wire that goes to the crank position sensor. Using the new manual, thank you Tim, I am going to do some continuity testing tomorrow to check the integrity of the wires between the PCM and the crank position sensor, there is where I believe I'll find my problem.
Good find. That is more than likely your root cause.

Good luck.
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post #23 of 28 Old 09-28-2015, 12:24 AM Thread Starter
bensimpson1981
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Just got back from hunting, no luck there either :-(
I have fixed the broken wires and they are all sending proper signals to the PCM but still the same problem. I also checked the ASD relay and it is good and getting proper voltage. I am so baffled.


Edit... I just rechecked the ASD Relay again and now it is not getting voltage from ignition.
Either bad wire or faulty ignition switch...?

Last edited by bensimpson1981; 09-28-2015 at 04:57 PM.
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post #24 of 28 Old 09-29-2015, 01:11 AM
bz5
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Any opinions on Crown auto parts.

Bob K
'91 XJ Laredo 4.0 NP242 Selec-Trac
'04 WJ Overland 4.7 HO NV247 Quadra-Drive
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post #25 of 28 Old 09-30-2015, 09:05 PM Thread Starter
bensimpson1981
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I found a burnt circuit breaker in the fuse block and I am now getting ignition voltage to the ASD Relay. Tomorrow I am going to test to see if the ASD Relay continues to get ignition voltage from the PCM all the way through cranking or if the PCM is cutting it off. If the PCM is not cutting it off then my problem lies outside the ASD/PCM Circuit. If the PCM is cutting it off then I have to find out what sensor signal it is not receiving that is causing it to shut off (I don't believe that it is cutting it off due to lack of sensor signal because I have tested the 5v reference on all sensors and they are all getting proper voltage, I have also tested the integrity of all of the sensor return lines between every sensor and the PCM and they are all good). This problem is acting like a bad PCM, but I find that hard to believe since the vehicle ran before replacing the intake. Is it possible that the broken wiring harness that I spoke of earlier caused a short that back fed voltage to the PCM on the wrong line and damaged the PCM? Is there a way to test the PCM? From what I gather it is a fairly expensive part. I am still not getting any codes for anything.
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post #26 of 28 Old 10-14-2015, 12:05 PM Thread Starter
bensimpson1981
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So, this problem has got me so frustrated.


I have replaced the crankshaft position sensor, camshaft position sensor, throttle position sensor, MAP sensor, idle air control valve/motor, ignition coil, cap, rotor, PCM.


All wires that were damaged have either been patched or replaced.
I have tested the integrity of all of the wires for shorts to ground, shorts to each other, continuity to their proper pin locations on the (PCM/ECM/ECU) powertrain control module. None are shorted, all are receiving proper voltage from the PCM.


The ignition switch is sending 12v to the PCM in both the run and start positions. The PCM is sending 12v to the auto shutdown (ASD) relay in the run position, HOWEVER, the PCM cuts voltage to the ASD as soon as you start cranking.


Obviously the PCM is looking for input from something and is not getting it thus triggering it to cut voltage to the ASD.


For the life of me I cannot figure out what is missing.
I think my next fix might be a stick of dynamite.


PLEASE HELP !!!!
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post #27 of 28 Old 10-14-2015, 06:37 PM
lsmurphy
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Have you checked the connections to the fuel pump? ground? possible the pump arcing out?

Just a guess.
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post #28 of 28 Old 10-16-2015, 06:10 AM Thread Starter
bensimpson1981
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Yes I have, they are all good.

The PCM is supposed to give 3 seconds to receive signals from the sensors before cutting off the auto shutdown relay. But the ASD relay is loosing power the instant the ignition is switched to start.

Ignition switch?
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ckp , cps , MAP sensor , pcm , tps

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