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Discussion Starter · #1 · (Edited)
I just bought a Durango that was not running. They said the dealer said the PCM was bad because the alarm would not turn off.
I replaced the PCM.
I unlocked the door with the key
The alarm stopped beeping
I started the truck
It died
I started it with my foot on the pedal
It runs but dies if I let go and it is rough
It has plenty of fuel in it, but after it runs for about 45 seconds the gas gauge drops to zero and says low fuel.
The securtiy light flashes the entire time.

Any advise and to what to try next? also no check engine lights but the battery was just hooked up because of the alarm going off and I don't know if it has had time to set a light.

This is the first 4.7 durango I have had and I am not really sure if it is normal or not for the security light to flash.
Also when its idling rough the rpms go up and down alittle
 

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Diesel Mechanic
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sounds like a security issue definetly. are you sure its the proper PCM for the vehicle? i havent seen a junkyard PCM work correctly yet.
 

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Discussion Starter · #4 · (Edited)
I put the old PCM back in. I started it and it would run for a few seconds with the gas down and then it would die and I could not get it to stay running very long. Then I put the new one in and it runs like first described.

edit:
I checked the air filter, Pulled out the IAC cleaned it and checked it to see if it moves when the key is turned on, put it back in, started it with the intake tube off. It will now idle a little smoother but still same issue. When I start it if I hold the RPMs high only the security light flashes. If I let it drop below 1k RPM the gas gauge goes to E and the Brake light comes on and the ABS light comes on. It stays on until I turn it off and start it again. I think it smells like its running rich.

I guess I am going to have to tow it to the dealer :cursin:
 

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Discussion Starter · #5 ·
I took it to the dealer.
They said there is a fault in the PCM
Also they said the miss is caused by something else and they believe its because of loss of compression.

The PCM was garanteed. They said I can get my money back or they can send me another one.

I am going to check the compression myself, but I think they are probley right about that being a problem.

Should I get a new pcm and replace the engine or should I just part it out?
The only thing I am afraid of is there being some kind of crazy wiring issue with it and that I will still have problems after fixing the engine and replacing the PCM again. The blue book is $4200 private party if it was running. The body and interior are pretty nice. The trans seems to shift good. I priced a 63K engine at $1750 and a grooms engine at $2800. I have $1k in it at this point and I can replace the engine myself.
 

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Jay
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isnt there a specific code for the security option? Like when they program a new key it needs to match the code or frequency of what is already in the truck. The eBay site might have just programed the vin and not the security code since its specific to each vehicle. When you took it to the dealership did you tell them you got the pcm off ebay? They probably need to program it there to get the security to work.
 

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Discussion Starter · #7 ·
isnt there a specific code for the security option? Like when they program a new key it needs to match the code or frequency of what is already in the truck. The eBay site might have just programed the vin and not the security code since its specific to each vehicle. When you took it to the dealership did you tell them you got the pcm off ebay? They probably need to program it there to get the security to work.
I told them the dealer exactly what I did. The place I bought the pcm from on ebay told me as long as the key was programed to the vin that the computer would work because the computer was also programed to the vin.
 

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Discussion Starter · #8 ·
I did a compression check and here are the results
Cyl-pressure
8-60
6-90
4-95
7-95

2-00
5-150
3-120
1-85

Is my engine gone?

Could the engine running so badly cause the pcm issues?
 

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Discussion Starter · #9 ·
Ok I got it tore down enough to lift the valve cover up a little. I looked at the cylinder with 0 compression and I noticed a rocker arm just sitting there on its side. I can't see the other one for that cylinder right now. I still have to pull some more parts to be able to pull the valve cover all the way off. From what I can see it looks like all the springs are fine, but there is just the two rockers off.
 

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Discussion Starter · #10 ·
Ok I loosened the cam and got the rockers back in, but the rear most one is loose and can be pulled out even with the cam tightened down. I guess it has to be something else. Maybe either worn cam or bent valve keeping the spring down some.
 

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I hate you people.
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Need pics to help with anything at this point.
 
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