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  #37  
Old 04-22-2012, 08:35 PM
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Re: 02 Overland- rough running at speed

I am sorry but there is a HIGH likely hood your dealing with a mechanical issue... clearly its not 100% but O2 sensors are going to cause problems on an entire bank not just 1 cylinder on each bank. combine with your compression numbers. I REALLY feel like your wasting a lot of money throwing parts to not fix the problem. Had you made the coil suggestion as I just did last week to someone I would have said NO, DO NOT DO THAT. Not that coils don't go bad but it takes all of 10 seconds to swap a coil to another cylinder and if it is a coil failure it WILL follow to the other cylinder.

I say this because this is going to get very expensive for you if you wait to actually diagnose a mechanical fault causing your concern till after you have replaced everything else. It is much less common that a misfire is a simple tuneup, injector, or coil than may other problems. Of course this is of the vehicles I see, I am sure there are many people who avoid the dealer like the plague that have vehicles that havent had plugs replaced since the car was driven off the lot 130k miles ago.

Just my .02 I really think your looking at a motor issue over sensor, coil, injector, again considering the compression readings and the fact you got it after a known overheat and the 4.7 is pretty sensitive to overheat.
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  #38  
Old 04-22-2012, 11:31 PM
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Re: 02 Overland- rough running at speed

Quote:
Originally Posted by 2005JGC View Post
I am sorry but there is a HIGH likely hood your dealing with a mechanical issue... clearly its not 100% but O2 sensors are going to cause problems on an entire bank not just 1 cylinder on each bank. combine with your compression numbers. I REALLY feel like your wasting a lot of money throwing parts to not fix the problem. Had you made the coil suggestion as I just did last week to someone I would have said NO, DO NOT DO THAT. Not that coils don't go bad but it takes all of 10 seconds to swap a coil to another cylinder and if it is a coil failure it WILL follow to the other cylinder.

I say this because this is going to get very expensive for you if you wait to actually diagnose a mechanical fault causing your concern till after you have replaced everything else. It is much less common that a misfire is a simple tuneup, injector, or coil than may other problems. Of course this is of the vehicles I see, I am sure there are many people who avoid the dealer like the plague that have vehicles that havent had plugs replaced since the car was driven off the lot 130k miles ago.

Just my .02 I really think your looking at a motor issue over sensor, coil, injector, again considering the compression readings and the fact you got it after a known overheat and the 4.7 is pretty sensitive to overheat.
Thanks for the comment. I am torn, but the sensors and reman injectors have run about $400 total and I can do the labor. Found great discounts trolling Amazon and Ebay. If it is the heads, then we are well north of a thousand for reman + labor. And hope springs eternal.

I will keep you apprised- you may very well be correct. Or I may get lucky. This was the risk that I took when I bought the truck, and the reason that I bargained the prior owner down to $2500 on a vehicle that blue books for 6 to 6.5K. I will test run between each step, so if I see a noticeable change after a modification I will make a note.

But I am learning a lot about how these engines work, and that is of some value. This is a project truck for me. Please stay engaged and keep on being critical! In my business, honest criticism is the best way to keep on track, so no worries - please do not hesitate to tell me when you think I am getting off the rails.
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  #39  
Old 04-28-2012, 03:40 PM
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Re: 02 Overland- rough running at speed

Quote:
Originally Posted by 2005JGC View Post
I am sorry but there is a HIGH likely hood your dealing with a mechanical issue... clearly its not 100% but O2 sensors are going to cause problems on an entire bank not just 1 cylinder on each bank. combine with your compression numbers. I REALLY feel like your wasting a lot of money throwing parts to not fix the problem. Had you made the coil suggestion as I just did last week to someone I would have said NO, DO NOT DO THAT. Not that coils don't go bad but it takes all of 10 seconds to swap a coil to another cylinder and if it is a coil failure it WILL follow to the other cylinder.

I say this because this is going to get very expensive for you if you wait to actually diagnose a mechanical fault causing your concern till after you have replaced everything else. It is much less common that a misfire is a simple tuneup, injector, or coil than may other problems. Of course this is of the vehicles I see, I am sure there are many people who avoid the dealer like the plague that have vehicles that havent had plugs replaced since the car was driven off the lot 130k miles ago.

Just my .02 I really think your looking at a motor issue over sensor, coil, injector, again considering the compression readings and the fact you got it after a known overheat and the 4.7 is pretty sensitive to overheat.
OK, did all that stuff. Replacement O2 sensors (Denso) throwing codes, not heating etc.

Each step seem to help running (except the O2 sensors), but the biggest difference was when I replaced the throttle position sensor.

I was hopeful about the injectors, as they looked pretty rough when I pulled them, but it made little difference.

I think that I am about to the point where I am convinced that you are correct- it is a valve or something related to a valve/head at #6 cylinder. SO- one last thing is to made sure that the injector is getting good signal, and then it is time to make arrangements to have the heads re-done.

Again, thanks to all for your comments.
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Old 04-28-2012, 04:06 PM
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Re: 02 Overland- rough running at speed

Quote:
Originally Posted by 2005JGC View Post
I am sorry but there is a HIGH likely hood your dealing with a mechanical issue... clearly its not 100% but O2 sensors are going to cause problems on an entire bank not just 1 cylinder on each bank. combine with your compression numbers. I REALLY feel like your wasting a lot of money throwing parts to not fix the problem. Had you made the coil suggestion as I just did last week to someone I would have said NO, DO NOT DO THAT. Not that coils don't go bad but it takes all of 10 seconds to swap a coil to another cylinder and if it is a coil failure it WILL follow to the other cylinder.

I say this because this is going to get very expensive for you if you wait to actually diagnose a mechanical fault causing your concern till after you have replaced everything else. It is much less common that a misfire is a simple tuneup, injector, or coil than may other problems. Of course this is of the vehicles I see, I am sure there are many people who avoid the dealer like the plague that have vehicles that havent had plugs replaced since the car was driven off the lot 130k miles ago.

Just my .02 I really think your looking at a motor issue over sensor, coil, injector, again considering the compression readings and the fact you got it after a known overheat and the 4.7 is pretty sensitive to overheat.
Anyone have recommendations for a shop for 4.7 HO engine re-build? Preferably in the South east, Ohio, Tennessee.

Seems that nothing major is going on, but the #6 cylinder mis-fire is persistent, and there was a history of overheating. About 170K miles.

BTW, when I was in under the truck removing the starter to replace the crank position sensor, there appeared to be fluid weeping from the right rear freeze plug area - which would explain the low coolant level which precipitated the overheating.
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  #41  
Old 04-28-2012, 04:53 PM
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Re: 02 Overland- rough running at speed

You may be best off buying a reman motor, I know there is one vendor that sells them that has supposedly fixed many of the factory flaws. Don't recall the name.
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  #42  
Old 04-28-2012, 11:26 PM
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Re: 02 Overland- rough running at speed

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You may be best off buying a reman motor, I know there is one vendor that sells them that has supposedly fixed many of the factory flaws. Don't recall the name.
If it is the outfit in NJ, they will not do 4.7 HO engines.
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  #43  
Old 05-16-2012, 02:06 PM
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Re: 02 Overland- rough running at speed

Just to close out this thread, the cylinder #6 problem was a broken valve lifter assembly, presumably due to the sleeve popping out when the engine was over heated, and then popping back in. I am in the middle of replacing the engine with a long block 4.7 HO from a dodge dakota 2005 (58,000 miles) which has been partially re-built including heads re-faced and re-mounted. In addition, the harness insulation near the left front O2 sensor had frayed and the wires were shorting, so that will be replaced. 2005JGC gets the diagnostic prize. Thanks again to all for your time and assistance on this.
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  #44  
Old 05-16-2012, 04:05 PM
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Re: 02 Overland- rough running at speed

YAY! what do i get??? Im just playin, sorry it went this way, at least you will have a bunch of fresh sensors on your new-to-you motor. Hopefully it wont give you too much trouble for years to come!
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  #45  
Old 05-16-2012, 08:49 PM
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Re: 02 Overland- rough running at speed

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YAY! what do i get??? Im just playin, sorry it went this way, at least you will have a bunch of fresh sensors on your new-to-you motor. Hopefully it wont give you too much trouble for years to come!
No worries- No harm/foul. like I had indicated above, I started my negotiation on price with the prior owner with the assumption that the engine was toast, and decided to drop the cash on the sensors, new coil packs, fancy plugs and re-built injectors because they could be used with a replacement long block if it came to that. The good news was that, by careful shopping, I was able to get great prices on all of the above, and will probably come out of this with quite a nice WJ for less that the price of just a Mopar reman 4.7 HO engine + installation. A testament to Craigs List, Amazon and EBay.
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  #46  
Old 06-18-2012, 12:43 PM
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Re: 02 Overland- rough running at speed

Further follow up- reconditioned 4.7HO long block from a 2005 dodge with 50K miles swapped into the Overland. During the process, a short in the upstream left O2 sensor harness was revealed. That was repaired, new O2 sensor (Denso, of course), everything stuffed back in (no small feat) and the truck runs like a new one! So, in the end, good outcome, and I have an Overland that has 169K on the clock but 70K on factory rebuilt trans and something like a new reman 4.7HO for about $4500. Not bad, despite the hassle.
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