2003 Grand Cherokee 4.0 P1391 + - JeepForum.com
 
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post #1 of 7 Old 05-13-2020, 07:34 PM Thread Starter
Kodak
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2003 Grand Cherokee 4.0 P1391 +

Long 1st post. I usually can figure things out without asking but kinda at a loss. Got this 03 Grand Cherokee 4.0 from a friend that threw his purse at it. Everything is in non driving situation, just in park no load.

I reset the computer and it would start and idle but eventually backfire and then missfire and die. Found this post (which I cant post) and turning the cam sensor helped a whole lot but something is still wrong. Eventually still misses and will backfire when slamming the peddle. I have to be real close if not dead on with the phasing. Fuel pressure is still good.

Codes before cam sensor timing P1391 P0352 P0353, P0135, P0141, P0161 whatever. They keep changing.

Fuel pressure prime 45 then 52 after it starts and stays there, holds pressure after off for a while more than 10 minutes.

Seems like fuel pressure but if I restart it is like new. Has a few cracked vacuum hoses that I temp sealed but no difference.

It's not fuel pressure as I thought I got a tester. Previous got all new coils and rail.

I would guess injectors but on restart it is fine and will rev up to 5k or more if I wanted for a limited time, it is not heat related but time related. At a loss.

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post #2 of 7 Old 05-13-2020, 08:27 PM
jtec
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P0135-1/1 O2 SENSOR HEATER FAILURE
P0141-1/2 O2 SENSOR HEATER FAILURE
P0161-2/2 O2 SENSOR HEATER FAILURE
check wiring to o2 sensors, also GROUND. Did anyone change sensors?


P0352-IGNITION COIL #2 PRIMARY CIRCUIT
P0353-IGNITION COIL #3 PRIMARY CIRCUIT
What plugs are installed? check coil spring boots.

P1391-INTERMITTENT LOSS OF CMP OR CKP
Use a scanner and set sync. Observe CMP and CKP waveform signals with a labscope

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #3 of 7 Old 05-13-2020, 08:45 PM Thread Starter
Kodak
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Don't have a labscope. Did you read my post?

2003 Grand Cherokee Laredo
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post #4 of 7 Old 05-13-2020, 08:53 PM Thread Starter
Kodak
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Will check wiring to O2 sensors.

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post #5 of 7 Old 05-14-2020, 06:56 PM Thread Starter
Kodak
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jtec

O2 sensors seem fine, wires unmolested and none are rubbing or worn through. Uppers and lowers, checked the connections and all clean with no sign of oxidation or anything bad. Coil packs new, everything looks fine. Old coil packs in the back of jeep look fine also. New copper plug Autolites, don't remember the number but crosses correct and gap all BTW .035 and .037.

Did remove the engine grounds, cleaned and reconnected, nothing close to bad. Removed and inspected every injector connection. All no sign of anything bad.

Cleared the computer several times after changing crank sensor position. I know I will never be dead nuts on but close should work at least to drive the thing somewhere.

Codes: 0353, 0351 and P1391. I could throw my purse at it but this idle miss happens right at startup a few seconds after not when getting hot. When getting hot it's much worse.

Plugs are black so my thinking lean condition is opposite and a rich condition.

I am still thinking something stupid somewhere but I just don't know where. lol.

Any guesses I haven't hit yet?

Is 52lbs too much? Injectors should still work I think.

Edit: I don't think I cleared the computer right, will recheck and update codes.

2003 Grand Cherokee Laredo

Last edited by Kodak; 05-15-2020 at 08:56 AM.
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post #6 of 7 Old 05-22-2020, 06:00 PM Thread Starter
Kodak
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Don't work on this all the time. Today I pulled the coil rail out to put in new plugs. All plugs were the same, not healthy but the same. Checking all the wires and harnesses it looks like the motor was replaces and everything is just hanging. Going in closer there is a ground connection just hanging in the wind. I still have not found a ground from the engine to chassis. It is a mess back there. Wish I could just power wash it but know clean with that will even be more issues.
Anyways that's my update.

2003 Grand Cherokee Laredo
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post #7 of 7 Old 05-25-2020, 11:16 AM Thread Starter
Kodak
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Posts: 6
Fixed the open ground, cleared codes and computer. Sometimes it starts just fine before stalling, fuel pressure good the whole time. Other times it misses right away.

Getting ign. coil codes 0351 0352 0353 So I will get another coil rail, these are relentless.
New code 1494 LDP vacuum leak. Will check for more leaks.

No more O2 heater codes so that ground must have fixed that part.

Lots of popping and misfiring like a huge vacuum leak but could also be the coil rail. Can't tell at this point.

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