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Randall C
Randall C, ASE Certified Technician
Category: Car
Satisfied Customers: 12886
Experience:  32 years Foreign / Domestic Cars All aspects of Diag and Repair
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95 trooper: it starts but backfires; it ran..ran perfectly..dohc

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Transferred powerpack off '93 trooper to '95 trooper, had wired it incorrectly, put powerpack back on '93 and made sure wires were in correct order and it starts but backfires; it ran perfectly before switching it out. 3.2 DOHC motoer Isuzu trooper

Tracer :

Hello, I am Randall. I have reviewed your question and working on it now. Will return shortly

Tracer :

so you are saying you took the coil pack off a 93, put on the 95 and it backfired. you corrected firing order on the 95 and it ran just fine. Put coil back on 93 and it backfires? is this correct or something else


No, that is not correct. It did not run correctly on the '95. It was running perfectly on the '93. I put it on the '95 because that vehicle did not have one. I took it back off the '95 because it didn't run correctly. I put it back on the '93 and it no longer runs correctly on that vehicle. I have been over the wiring 3 or 4 times according to Chilton's. The wiring diagram shows that the right bank cylinder is 1, 3, and 5 and the left bank 2, 4, and 6 and that is how I have the wires distributed to the coil pack. It starts but backfires.


Should I still be waiting?

just saw your reply, Unsure why. is this the way you have them? this is the corerect for the DOHC engine

Customer: replied 6 years ago.
Yes, frustrated because it worked before I took it off and put on the other and now it doesn't. I already had this diagram from Chilton's, so I am sorry but you haven't provided any new suggestions.
I am / was only at step one. I am not there and no way to know exact diagram you looked at. Did you take each coil off one at a time>?
Customer: replied 6 years ago.
no, took all three off
trying to understand. did you remove the coils and module as one unit? or did you unbolt each coil and transfer to the 95? did module move over as well.
Customer: replied 6 years ago.
removed it as 1 unit
backfiring, is it only when under load and runs smooth at idle or missing bad all the time?
Customer: replied 6 years ago.
missing bad all the time
have you identified which cylinders are possibly not firing by removeing one wire at a time till you find one or more that will still allow engine to run but maybe only on 4-5 cylinders. hard to explain. You would pull a wire from coil, if no change in engine, move to next etc>?
Customer: replied 6 years ago.
no, i haven't tried that
ok, very possible you have wires on correct. So,, these coils are very sensitive to handling. I have run into so many over the years that develop a carbon track or very small hairline crack in them from a post to the bolt that holds them.either something on the 95 damaged the igntion module , or you have wires wrong or you may now have faint crack in a coil. I would try to get a spray bottle of water, Run engine and mist down the coils, look for sparks or really starts to run bad confirming what I think. You can los look real close at each coil with flashlight looking for very faint cracks. water works best. we do this often in the shop
Customer: replied 6 years ago.
when i take 1 and 4 off it runs much worse; doesn't seem to make any difference when i take the others off; should i still try the water?
yes, you need to try everything I mention, the engine will not reallly run at all on just 2 cylinders, generally takes minimum 3-4 cylinders to stay running at all. I am still thinking problem with one coil. trying to determine which one. water is a good start or visually for very faint cracks
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Customer: replied 6 years ago.
sprayed water, saw nothing and ran the same, looked with magnifying glass and saw nothing
I have given all the info I can not being there. I will need to opt out and let another expert chime in on this one. One should help soon.Please dont respond to me as it will lock question to me only.