Sputtering and dying HELP - JeepForum.com
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post #1 of 70 Old 06-09-2016, 09:15 PM Thread Starter
JDNightFox
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Sputtering and dying HELP

1989 Wrangler 4.2L with complete top end from a 94 cherokee (MPI system & harness, sensors, etc)

Okay so I drove 250 miles through the AZ mountains no problem but as soon as I hit I-40 I got about 30 or so miles in and the engine suddenly started missing real bad then just cut out completely

I tried restarting it but it would just sputter and die instantly, or just crank with nothing

I let it sit there for about 20 or 30 minutes and it started up fine like nothing was wrong


it did this about 9 or 10 times so far, I made it to Albuquerque at least

I replaced the coil pack the first time it happened because I thought that was it, but it did it again about 30 miles later so I thought it was the TPS and unplugged that sensor, drove fine for another few miles then started doing it again, so I tried the MAP sensor, same thing

there are no check engine codes coming up, that is what frustrates me

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post #2 of 70 Old 06-10-2016, 04:36 AM
OHbandit
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You need to first figure out if it's fuel related or electrical. When it quits, check and see if you can hear the fuel pump cycle on for a couple seconds when you turn the key to the run position.
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post #3 of 70 Old 06-10-2016, 06:04 AM
Que89YJ
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Quote:
Originally Posted by JDNightFox View Post
1989 Wrangler 4.2L with complete top end from a 94 cherokee (MPI system & harness, sensors, etc)

Okay so I drove 250 miles through the AZ mountains no problem but as soon as I hit I-40 I got about 30 or so miles in and the engine suddenly started missing real bad then just cut out completely

I tried restarting it but it would just sputter and die instantly, or just crank with nothing

I let it sit there for about 20 or 30 minutes and it started up fine like nothing was wrong

it did this about 9 or 10 times so far, I made it to Albuquerque at least

I replaced the coil pack the first time it happened because I thought that was it, but it did it again about 30 miles later so I thought it was the TPS and unplugged that sensor, drove fine for another few miles then started doing it again, so I tried the MAP sensor, same thing

there are no check engine codes coming up, that is what frustrates me
Disconnect the o2 sensor. It force's the ecu into open loop. See if it makes a difference.

Fault codes:
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post #4 of 70 Old 06-10-2016, 06:42 AM Thread Starter
JDNightFox
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1989 YJ Wrangler 
 
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Quote:
Originally Posted by OHbandit View Post
You need to first figure out if it's fuel related or electrical. When it quits, check and see if you can hear the fuel pump cycle on for a couple seconds when you turn the key to the run position.
fuel pump does cycle on when I turn the key, it also cycles when I start cranking it so I know the CPS is working too
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post #5 of 70 Old 06-10-2016, 06:47 AM Thread Starter
JDNightFox
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Originally Posted by Que89YJ View Post
Disconnect the o2 sensor. It force's the ecu into open loop. See if it makes a difference.
I guess I can try that next, the O2 sensor was bought new when I did the swap though so it only has maybe 8000 miles on it
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post #6 of 70 Old 06-10-2016, 07:02 AM
Que89YJ
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So, did you hook up the check engine light? How are you checking codes?
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post #7 of 70 Old 06-10-2016, 08:13 AM Thread Starter
JDNightFox
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Quote:
Originally Posted by Que89YJ View Post
So, did you hook up the check engine light? How are you checking codes?

Yeah I have it hooked up, would a bad voltage regulator cause this? I know m alternator gauge was showing 12v yesterday and now it's showing 14
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post #8 of 70 Old 06-10-2016, 08:32 AM
Que89YJ
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A charge issue definitely can. Keep your eye on it and see if the voltage correlates to the problem when it happens.
I would think that you have a sensor issue though. Try this. Next time it happens disconnect the battery and let it sit for 10 seconds. Just a long 10 count. Hook it back up and see if it starts. If it does then maybe a bad crank sensor.
O2 trick is to force it into open loop and a default calibration. It will run rich but no big deal if it keeps you on the road. If it doesn't rehook up the battery and pull the battery cable for the 10 count to clear the codes.
No codes? So you don't see 12 and 55?
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post #9 of 70 Old 06-10-2016, 08:38 AM Thread Starter
JDNightFox
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Quote:
Originally Posted by Que89YJ View Post
A charge issue definitely can. Keep your eye on it and see if the voltage correlates to the problem when it happens.
I would think that you have a sensor issue though. Try this. Next time it happens disconnect the battery and let it sit for 10 seconds. Just a long 10 count. Hook it back up and see if it starts. If it does then maybe a bad crank sensor.
O2 trick is to force it into open loop and a default calibration. It will run rich but no big deal if it keeps you on the road. If it doesn't rehook up the battery and pull the battery cable for the 10 count to clear the codes.
No codes? So you don't see 12 and 55?
Yeah I've got 12 and 55 so I know the computer is still good
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post #10 of 70 Old 06-10-2016, 11:59 AM Thread Starter
JDNightFox
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Okay it did it again and I unplugged the oxygen sensor then it started and drove for another few miles but sputtered and died again
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post #11 of 70 Old 06-10-2016, 12:16 PM
Que89YJ
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I would think that you have a sensor issue though. Try this. Next time it happens disconnect the battery and let it sit for 10 seconds. Just a long 10 count. Hook it back up and see if it starts. If it does then maybe a bad crank sensor.
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post #12 of 70 Old 06-10-2016, 01:39 PM Thread Starter
JDNightFox
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My crank sensor is on the front of the engine where I can easily reach it, I can unplug that one instead if that's what you intend the battery unplug to do

Also I'm pretty sure it's heat related because when it dies, if I open the hood and let it cool off for 5 minutes or so it starts up fine

Also, my alternator gauge is reading 14v, if I turn on the heater it drops to 13-ish, is it supposed to be reading 14???
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post #13 of 70 Old 06-10-2016, 08:08 PM
Que89YJ
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Quote:
Originally Posted by JDNightFox View Post
My crank sensor is on the front of the engine where I can easily reach it, I can unplug that one instead if that's what you intend the battery unplug to do

Also I'm pretty sure it's heat related because when it dies, if I open the hood and let it cool off for 5 minutes or so it starts up fine

Also, my alternator gauge is reading 14v, if I turn on the heater it drops to 13-ish, is it supposed to be reading 14???
Yes.

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post #14 of 70 Old 06-10-2016, 10:40 PM Thread Starter
JDNightFox
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Alright so whatever the issue is, I know it must be heat related because the distance I can drive is proportional to how long I let the engine sit after it dies

I'm still thinking it's the alternator overheating, I have an electric fan and with it being summer it's running constantly
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post #15 of 70 Old 06-11-2016, 03:20 AM
Que89YJ
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Quote:
Originally Posted by JDNightFox View Post
Alright so whatever the issue is, I know it must be heat related because the distance I can drive is proportional to how long I let the engine sit after it dies

I'm still thinking it's the alternator overheating, I have an electric fan and with it being summer it's running constantly
The fan shouldn't be.on above 30'mph. Does the temp gage stay in normal range?

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