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Post 420a engine swap issue

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tr4w

Probationary Member
2
0
Sep 22, 2009
Alton, New Hampshire
Here is a where we have been:

We have a 99 eclipse 420a it had a bad lower end knock so we decided the quickest fix was to do a drop in replacement with a used motor and then investigate the rebuild of the original motor. So we located a rust bucket donor car, 95 eclipse, the motor seemed to run strong.

We executed the swap. We did the entire motor an tranny together. Before putting the motor in we replaced the water pump and timing belt. Once we got the motor in place we realized the ECU and several of the sensor connections were not the same between 95 and 99 motors. We decided to leave the 99 ECU in place in the car and swapped sensors where we could from the 99 motor tot the 95 motor. The only catch to his was the line of sensors on the back side of the motor. There were several hear that were corroded in place and we could not get out to swap. So we cut the harness and wired in the connectors from the 95 harness so they would mate with the existing 95 sensors. :nono: I am an electrical so I am fairly confident in my wiring and soldering skills. But of course mistakes do happen.

Once we got it all back together (95 motor in 99 eclipse). The car actually started :thumb:
But it was running rough. We got the code P1390. And quickly realized we had screwed up the timing belt install:ohdamn::ohdamn:

So we re-read the shop manual and proceeded to redo the timing belt install on the car. Not a pleasant job. But this time I think we got it right.

Where we are now:

:banghead::banghead: The car now runs smooth as silk when it starts an keeps running. The problem it randomly starts and the just shuts off. It does not choke or sputter or run rough. It will start run for about 20 seconds and shut off just as clean as if someone turned off the ignition. When you try to start it again it won't fire. On and off several more time and a restart and it might fire up. If it keep running for more than 20 seconds it again runs smooth as silk. Both at idle and under power. We are still getting the P1390 code even though the car runs like it is in perfect time. :banghead:

I believe the issue is in the difference between the ECU's of the two years. And most likely either the crank of cam sensor. Both of which are different between the two years. But I ma unsure of how to correct it. My biggest fear is the recommendation may be put the 95 ECU and wire harness in the car. This does not seem to be an easy undertaking. Or maybe I am way off and someone has a better idea.

I am wide open to suggestions.

Thanks,:hmm:
 
it sort of sounds like a computer issue but dont quote me on that.
i used to have a 91 blazer that did the same thing after i swapped engines and the computer didn't work right afterwards.
 
Are you sure the 99 computer didn't have any issues since you never ran the car? Fix your trouble code first. I have a couple sensors and plugs on my car that are from a different year and they work fine.
The 99 ECU is good the car was running good until rod bearing issue.
 
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