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Discussion Starter · #1 ·
Alright, here is my problem. I have a 1998 Durango with the 5.2 engine. It has 292,xxx miles on it and it's been a jewel up till now.

The check engine light came on and started flashing. The code, at that time was P0306, detected misfire on #6 cylinder.

First fix was a complete tune up. New plugs, wires, cap and rotor. The plug that came out of 6 looked exactly like the other 7. That didn't cure the problem.

Second fix was a new crankshaft position sensor. While replacing the sensor, I discovered that the plug on the harness side had severely corroded wires. Replaced the plug and wires. Still, no cure.

I did do a compression check, #6 was at 92lbs, consistent with the other cylinders +/- 5lbs.

It does misfire but it does not do it consistently. Under load or coast, makes no difference. It seems totally random as to when it decides to act up.

I've been trying to troubleshoot this thing for over a month now. In addition to the parts listed above, I've swapped the injector for a known good one and I've replaced the MAP sensor.

Whatever is failing won't just give up and fail. Since the original P0306 code, I've gotten P0300 and a code for every cylinder except #5.

The engine has never been apart and has received it's regular maintenance. Minus the MAP and CPS sensors, everything is original.

I'm at my wits end right now. I live 20 miles down a dirt road, 50 miles from the nearest services of any kind. I need this old girl to be reliable again so I'm asking for your ideas as to where to look next.

Thanks.
 

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a mis fire would be 1 cylinder .. some of the things you mention would effect all cylinders .. so your looking for something related to 1 cylinder ......  plugs wires cap ,      and        fuel injectors / their wires/connectors . all the injectors get power + constantly when key is on , running, EACH injector gets a ground from the pcm when its time to fire . So there are 8 connections at the pcm plug , and 8 separate ground wires to the injectors . I'd suspect a bad injector , or its connection at the injector first  ( AH ! you did that !) or a clogging  fuel rail ... next look at the harness from that injector back TO the pcm connector . ( ugh )    also note a mechanical problem could cause it , lifter , valve guide/seat .... does it "use" coolant ?
 

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Coil? Do you have an Accel coil if you do get rid of it.
 

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Discussion Starter · #4 ·
I'm gonna pick up a new coil today and give it a shot. It IS the original so it couldn't hurt.
I'm shying away from a mechanical issue because there is nothing consistent about the way it's acting. She doesn't use any fluids, no smoke from the tailpipe, all the plugs look identical, cap and rotor look good, no play in the distributor....... I'm just not seeing the evidence for a mechanical failure. On the other hand, if I have to dig through that wiring harness, I may just hang myself with it. Lol. That thing is a serious pain in the rear.

Thanks, I'll keep ya posted.
 

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Coils can do weird things they can test out fine when they're cold when they heat up they act up or they give a really weak spark that might be just causing your misfires and remember do not unplug any sensor in that vehicle unless your battery is disconnected. I on the other hand had to bed crank sensors that were giving me the random misfires in my 2001. And a shit Accel coil that would give out weak spark when it wanted to. The best thing to do is try to stick to the stock Mopar coil if you don't have an MSD or anything like that.😎    also again if you unplugged the crank sensor when your battery was connected or installed it that may very well also be your problem right there.
 

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why in the world would a single coil set up cause only # 6 to missfire ?  seems like it would be completely random any cylinder any time . but whatever .
 

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Discussion Starter · #7 ·
It is totally random as to which cylinder or cylinders it says is misfiring. The only one that hasn't popped up is #5. After every change I make, I clear the codes and start again. After the MAP sensor was changed it gave me P0300, P0301 and P0302.
Many years ago my power wagon had a coil issue. Ran great cold and as soon as it warmed up, it would shut down. I'm wondering if it's not the same type of issue here. Guess I'll find out.
 

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🤔 you also said you had misfires on every cylinder
 

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I had the same problem with an 03 durango with the 4.7

I sold mine after full tune up new plugs coils battery computer and still no cure.

I later found out there is a a known ground issue having to do with the power steering pump that causes random misfire. they do have a wiring kit to fix it for like $150.
 

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RamProject440 said:
I did do a compression check, #6 was at 92lbs, consistent with the other cylinders +/- 5lbs.
92 pounds of compression?!!! and all others the same?!!! ... that motor is very worn out or your compression tester is bad... not worn out magnum motors put out at least 160 pounds of compression and that is with some miles on 'em
 

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Yeah I just caught that or you're doing the compression test wrong
 

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Discussion Starter · #12 ·
***Update***

Replaced the coil with a new OE unit, no change in performance.

That being said, now it is giving me the P1391 code with NO check engine light. It stutters worse under a load, I.E. heavy throttle, and it stutters under even throttle (cruising), just not as bad.

Looked up the 1391 code and it say it's the camshaft position sensor..... I can't find a CMP on this engine....

That leads me to believe 1 of 2 things. It is either hiding in some deep dark recess and engineers are laughing their asses off OR it's the plate under the distributor cap (AKA the distributor pickup coil).

Ideas?
 

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Yup. It's the sensor in the distributor.
 

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  Is the problem better or worse when you first start it . I had a 5.9 that miss once it warmed but not when cold. It was a small crack in the head at a valve. It ran perfect on start up and only missed when full warm.  The compression test didn't show much but a hot leak down test did.
    In the photo you can barely see the little crack.
 

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lopaka311 said:
I had the same problem with an 03 durango with the 4.7

I sold mine after full tune up new plugs coils battery computer and still no cure.

I later found out there is a a known ground issue having to do with the power steering pump that causes random misfire. they do have a wiring kit to fix it for like $150.
is this particular to the 4.7 and/or the 03? I have an 01 5.9 that has been driving me nuts, fresh engine (brand new EQ heads even) and the injectors went wide open, melted down a brand new cat, injector on parameter went to 17.1 secs on time, like 5x what it should be.... washed out the cylinders like a stuck float would..... had a #6 misfire on the original engine that I had dome everything to, to try and solve, decided it had to be internal even though like the OP there was no real proof, so with 258K I decided I didn't want to just do the top end....
new engine ran like a top during break in, before my initial test drive with new engine in place. had about 2 hours un time on that engine before that initial test drive. about 4 miles away from home I had to call my son with his truck and a chain.
 

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Volaredon your injectors get power full time and are triggered by grounding through the injector's driver in the computer. Your injector may be stuck, driver is bad or the ground wire from the injector to the computer is shorting out.
 

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injectors had been thru a BOSCH certified fuel injector service, on 2nd computer, 2nd complete engine wiring harness.  did 1st oil change and came out as a powdery metal slurry. NEVER had that happen on a fresh engine job. Ever. probably rebuilt ~15 car engines from the bottom up over the years, not (quite) a rookie.  electrical/electronics/fuel injection has always been a thorn in my side.  that is why I still hate EFI.
 

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first time for everything ,  forensics now required ...
 

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volaredon said:
is this particular to the 4.7 and/or the 03? I have an 01 5.9 that has been driving me nuts, fresh engine (brand new EQ heads even) and the injectors went wide open, melted down a brand new cat, injector on parameter went to 17.1 secs on time, like 5x what it should be.... washed out the cylinders like a stuck float would..... had a #6 misfire on the original engine that I had dome everything to, to try and solve, decided it had to be internal even though like the OP there was no real proof, so with 258K I decided I didn't want to just do the top end....
new engine ran like a top during break in, before my initial test drive with new engine in place. had about 2 hours un time on that engine before that initial test drive. about 4 miles away from home I had to call my son with his truck and a chain.
I'm not sure if it was 4.7 specific though I can't see them having multiple power steering units per year. So I'm going to guess what ever years used that same power steering unit would have the same issue.
 

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Discussion Starter · #20 ·
Okay, I replaced the camshaft position sensor and it's still having the same issues. I can't say that nothing has changed because now I get the random misfire without the check engine light or a code.

Again, this misfire seems to be totally random. It does it when it feels like it, I cannot totally recreate it. I have a hard time going with a mechanical failure do to the fact that it is not consistent. Is it possible? Sure, but I don't see the evidence for it yet.
Yes this thing is pushing 300k. Yes, this engine is tired. I just can't go down the mechanical failure road yet. I'm at the point where I'm just going to have to drive it until whatever is failing, fails. At least then I'll have a starting point for fixing it.

 
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