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2002 dodge Durango slt 4.7L

I had the engine swapped out. Turns out the engine put in was from a 2001. The car cranks but won’t turn on. Inside someone suggest the engine put in has 16 teeth gear and in need a 32 teeth gear. Another said change the ECM and wiring harness. What would be better?

I have jeep liberty’s with the 3.7 engines . The 3.7 is basically a 4.7 with two fewer cylinders . The 02 & 03 liberty’s used a different reluctor ring on the crankshaft & a different tone ring on the camshaft than the 04’s & up . The computers changed in 04 & up . To install an 04 & up engine in an 02 or 03 those previously mentioned rings have to be swapped into the 04 & up engine which requires crankshaft removal . It requires fairly extensive engine disassembly with the engine out of the vehicle .
That being said , it is still considered easier to do the engine work than to swap computer & wiring systems . The number of teeth on the reluctor ring & the windows in the camshaft tone ring are different in the year model engines I mentioned which led me to believe this may be the same problem you’ve encountered in your 4.7 swap .
As I said before , in the 3.7 world people do the ring swaps in the engines & leave the computer & wiring alone . I would make sure this is your problem before progressing though . Hope this helps .

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I’d change the ECM I think in that situation I think. It would be preferrable if you could get the ECM and engine wiring harness from the same wrecked car you got the used engine from.

Why is not the shop that did the swap working on solving the problem?


If it’s anything like a Liberty you’d have swap a lot more wiring than just the engine wiring harness . The pcm controls transmission functions & a host of other things .

I believe the 16 tooth tone wheel is used with the early JTEC controller and the 32 tooth tone wheel with NGC controller, two different levels of PCMs and different connectors and harnesses.

Replacing the engine is easier than replacing the crankshaft and either is much easier than retrofitting to the other PCM system.

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If I was the OP & not doing the work myself & paying to have it done & it is determined that this engine isn’t compatible with his PCM , this is what I would do . I would remove & sell that engine & purchase one that is compatible & install it .

Anyone heard of a “generic ECM” product that can be used for just about any car? It seems like that’s what needed for folks who want to fiddle with old cars, like people do now with cars of the 60’s and early 70’s where its relatively simple to swap parts, but for the kind of old cars from the 80’s and 90’s that use make/model/year/power-train configuration specific ECMs. It seems like it would be possible to manufacture a generic electronics box you buy, then you plug all the sensors into it, maybe you have to pre-program it using your desktop PC for what sensors to expect, then it learns how to run the engine by a trial and error process. It seems like something like that must be available. Anybody heard of this, or used one?

I think that might get you in trouble, when it comes time to get the car smogged

If the machine somehow detects that the pcm is wrong in any way . . . calibration, model year, application, software version, etc., I imagine you’d fail, and it might be considered tampering

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Yes, I believe it is called “Megaspark”. The problem is that the owner has to do all the programming and that is a deal buster for most people. If your lucky, you might find someone who has successfully programed one for a vehicle identical to yours.

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