We have a 1995 Dakota 4X4 with a 5.2. The engine spun a bearing so we found a replacement 5.2 but it is from a 97 Jeep and were told it was running fine before it was pulled. We swapped over the intake, exhaust, oil pan and all other sensors from the 95 to the 97 and installed the motor.

It runs like crap. Will not idle, seems to have a miss and backfires through the exhaust. We did not change the 97 flex plate on the replacement engine to the one from the 95. Could this be what the problem is?

I did see the part number for the flex plate is different 95 vs 97.

Does anyone have both and can compare the 2 to see if there are differences in the spots where the crank sensor gets its signal on the flex plate?

We have checked the spark plug routing and firing order several times and it is correct.
Also cleaned the idle control valve and changed the MAP sensor.
Verified no vacuum leaks.
There are no codes in the computer.

If we do need to change the flex plate is the any way to do it without removing the engine again?

Thanks

 

What did you do with the crank sensor? They are frequently victims of engine/trans swaps...... bend it, or break it, and the engine won't run worth beans.

 

Yeah we were careful with the crank sensor with this truck. On a prior swap with a different truck last year it broke lining up the transmission.
Also there are no codes in the computer.

 

If you didn't install it after everything else was all together.... I would still have a look at it.

 

You can swap the flexplate by disconnecting the trans and torque converter and sliding the trans back til you have enough room to get to the flexplate bolts. Did you swap over the distributor from the 95 to the 97? If so you may be looking at a sync issue with the distributor

 

Thanks for the tip on moving the trans back.
No we did not change the distributors, but that is the next thing we are going to check.
We are not sure of the history of the donor motor so who knows what was done to it before we got it.
It needs to warm up some though the truck is outside on it is no fun working on it when its 30 degrees.

 

both are 5.2 (318) neither is 5.9 (360) the 318s are internal balance, the 360s are external balance. starting in 96 they made all the converters the same between engines.
up til 95 all had 1 converter bolt hole slightly offset so they would only bolt to the converters 1 way. to keep the balance weights on the converters for those that needed them (the 360s, and some big blocks) located in the right location in reference to the crank. Starting in 96 they didn't offset the holes on the flexplate to converter any more, so the converter can bolt up anywhere, any of the 4 holes in the flexplate can match up with any of the 4 holes in the converter. From then on, the weights on a 360 were on the flexplates instead. like they should have done 25 years sooner..... ALL have the same goofy offset bolt pattern where the flexplate goes to the crank, so the flexplate is keyed to the crank and will only line up in one place. back to at least the 1960s. If yours is a "late" 95 it might already have the newer style flexplate. Side by side looking at them you cannot tell them apart. Used to be, when you'd order a trans from Mopar they'd come with a new flexplate.
That said, even if you could only line up 3 converter to flexplate bolt holes, it would run fine. Both are 318s , the long block is the same 92-03. The flexplate is NOT your problem. (nothing to do with why the engine isn't running right anyway-- to be right, and strong so the flexplate doesn't crack, it needs to be supported at all 4 places. Now if you'd said you were going from a 6 to an 8, that would be different. the 6 only has 6 windows for the crank sensor to read, while the V8 has, yeah... 8 of them. I don't think it would even run.
but yes I have seen many smashed crank sensors on a trans install.....

On that converter to flexplate bolt up deal, you can cheat and oval that 1 hole in the flexplate that is 1/2 a hole out of whack with a die grinder. I would still unbolt the converter and trans and push the trans back a couple of inches....you might be able to just unbolt the flexplate and spin the converter a bit so that the mounting block is offset from the hole in the flexplate so the nub of the die grinder can poke thru and not contact the mounting lug...… (to keep from buggering the threads in the mounting lug)

I wasn't there to help with/see what was done with the engine swap. There are several places that things can go wrong in the process. did you leave the distributor cap on and smack it against something as you swung the engine in/out? Plug wires on in the right order? Sync set on distributor? Injectors plugged in all the way, and to the right injector? vacuum lines connected right?
Ive done engine swaps on these before both newer>older and older>newer. It isn't that the engine came out of a Jeep. Other than oilpan (maybe depending on what it came out of/going into) and things like EGR or no EGR, 318 Magnum is a 318 Magnum. my last was a 318 out of a 94 Dakota into a 97 Ram 1500. all I had to do was the intake (97 didn't have EGR, 94 did) and oil pan (though because I went from small body to big body I could have left alone and it would have worked just fine)

I just re read your post... I see that "you were told" it ran fine in the Jeep. Now did it, really? Did you hear it run when it was in the Jeep? maybe it didn't. What happened to the Jeep that made the engine "available? Wreck? or did they swap the engine out of the Jeep because there was something wrong with it? I forget the year they eliminated EGR from "most" engines besides Calif. I'm thinking 95 might have been the 1st year without it. I'm quite certain the 97 wouldn't have had it.

 

Wow thanks volaredon that was a lot of helpful information!

I think we will leave the flex plate alone for now and focus on something else.

The firing order is right checked that several times. The next thing we'll double check is the injector order, vacuum lines and distributor.

We know nothing about the donor Jeep. My son bought the Dakota for basically scrap price. The blown 5.2 engine was under the hood and the jeep 5.2 motor was in the bed. The guy selling it had lost interest in fixing the Dakota and just wanted it gone. He was told the motor was a 145k motor that ran well before it was pulled, but who knows.

This was supposed to be pretty straight forward (5.2 to 5.2) compared to the last one we did (3.9 to 5.2). That one was extra complicated because the donor 5.2 5spd was a 96 and it was going into a 95 was 3.9 5spd. We changed the computer and under hood and cab wiring harness so the 95 is now OBD2. I was expecting all kinds of problems with that one, but hooked everything up and it fired right up has has been running fine for a year.

 

This has us stumped.

Were rechecked the fire order, vacuum lines they are correct. Fuel pressure is within specs and it holds pressure, Computer still has no codes. EGR checked, changed coil, checked the timing it's with specs, checked the distributor it is synched within specs.

It still runs like crap, will not idle, backfires through exhaust and will only keep running if over 2k rpm. After a while of running at 2K the drivers side exhaust manifold gets glowing orange the passenger side does not.

The data on the scanner says it is running lean, but the exhaust smells and looks rich.

 

The ECU THINKS it's lean, and it is on the driver's side!

It's enriching the PASSENGER side to fix it.

Have you used a NOID light on each of the injectors on the driver's side?

RwP