02 Dakota 4.7 SLT issue - DodgeTalk : Dodge Car Forums, Dodge Truck Forums and Ram Forums
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post #1 of 5 Old 06-16-2019, 01:59 PM Thread Starter
Phillipsracing
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02 Dakota 4.7 SLT issue

I bought this truck non running gold it had a head issue. Pulled heads and found valve seats dropped. Had both heads completely redone, installed HO cams from a 4.7 jeep cherokee, new timing chains and tensioner, new coils, new plugs, new catalytic converter, new o2 sensors, new cam positioning sensor, new throttle position sensor. Truck started right up when completed idles beautifully at 500 to 600 rpms. I start to move the throttle and it starts to stumble once it stumbles then it gives check engine light with multiple engine codes P0345 ign coil primary and secondary sometimes one cylinder or all 8 cylinders. I can push throttle all the way to the floor and it stays at 1000 rpm. Sometimes I can get it to go above 1500 and it will run fine
It will not accelerate very well it just seems to be half hearted. Will not spin the tires or anything. I must admit I am stumped and need help as I am not sure why it will not throttle up with out stumbling to 1500 rpms. It's great if i can get it above there without a stumble. Any ideas would be greatly appreciated.Thank you
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post #2 of 5 Old 06-18-2019, 08:40 PM
steveinglendale
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Sounds like an ECM issue given the various inconsistent codes and maybe a "limp home" default kicking in. Dealer can try reflashing it to clear out cobwebs. Or it may work to get the one from the donor for the cams, if compatible, just a guess here. And then there's a new ECM that'll damage your pocketbook. Good luck. Looking forward to reading the solution.
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post #3 of 5 Old 06-18-2019, 10:20 PM
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Does not sound like an ECM issue to me. Limp home doesn't run like that. Sounds like you installed something the wrong way or you've got a defective part and are not getting a valid position/timing signal from the crank position sensor. You really need to get a scan tool on this and find out if you've got a valid crank position signal. It's always a big risk buying something not running, you have no way of knowing what's actually wrong.
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post #4 of 5 Old 06-19-2019, 01:11 PM
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Getting a non-runner comes with risks and rewards, too. A bad sensor or two, or something installed incorrectly may give indecihperable information to the ECU. But, I assume from the knowledgeable description that you've rechecked mechanical things like cam position timing, compression, etc. Guyonearth's response doesn't account for the dozens of rebuilds that work right out of the gate I've done that went way further with replacements from third party sources. Sometimes teething goes with the territory. You could have bad sensors even OEM's. One thing you might want to try is old school. If you kept the old parts try replacing sensors one by one to see if you get more normal readouts from the OBD II it appears you are using. Of course, you could have a bad old part, but if the valve seats were loose before all the work - not running or running well would be expected. The clatter and poor exhaust/intake signals going to the computer would want to shut it down for self protection. ECM's are pretty sophisticated dedicated computers, and can become corrupted or just wonkie on their own. My son's 924S Porsche went through several that misbehaved. Caused it to go bye bye. Had similar issues with a Ford and a Mercedes.

Last edited by steveinglendale; 06-19-2019 at 01:21 PM.
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post #5 of 5 Old 06-19-2019, 06:37 PM
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The point is the problem needs to be diagnosed. Diagnosing a problem does not consist of replacing random parts until a problem is fixed. It's entirely possible that there is an issue here with broken wiring, shorted harnesses, or some hidden damage from the previous owner that will not be solved by simply attaching new parts. Shotgunning parts is never the way to fix a vehicle. Sensors rarely go bad, and if they do you'll typically get a discreet OBD code that will tell you where the problem is. Seriously, taking an old non-running engine with unknown history and installing a pile of new parts on it is simply the wrong approach for a whole spectrum of reasons, and any competent mechanic would tell you that. If you used a scanner, you'd know in a second if you were in limp in mode, and you could quickly pinpoint values that were out of expected ranges. If you have multiple PIDs that are out of range it's obviously not a "bad sensor". You can buy very capable scan tools in the sub-$400 range these days.

Don't ever, EVER, believe what a seller tells you about a vehicle. If they're not lying, they may not even know. I used to buy a lot of "fixer uppers". I bought a cute Audi one time that "just had a blown head gasket". Know what was actually wrong? The engine had been massively overheated, the head was cracked in a hundred places and had been taken off and reinstalled with silicone gasket maker. The exhaust valves were melted. Coolant had blown out the intake and filled up the air box and got into the fuel distributor, which was seized. The exhaust was full of coolant gel. It took weeks of work to get that car to run. I've learned to always expect the worst, because that's usually what it is.

Last edited by guyonearth; 06-19-2019 at 06:46 PM.
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