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No spark on cylinder 2 and 5


NAXJA Forum User
Acquired a 91 XJ that was not running and didnt have a computer or trans in it. installed salvage yard computer, new coil, new fuel pump and new cap and rotor.
set TDC on crank, #1 piston and rotor put it all together and she will not start! No spark on #2 and # 5 cylinder. I used the same wire to check spark on all cylinders again 2 & 5 no spark any IDEAS?
thanks in advance for any info. I think it may be the computer?
also the trans is out and i just hooked up the flexplate bellhousing and starter just to try to get it to start. could the wrong flexplate if it is wrong cause this problem. ( my flexplate has three sets of four square holes around it for the CPS pickup)
thanks again
Double check the numbers on the computer. Could you have gotten the 4 cyl computer????
The computer i grabbed ddint have any numbers on it but it was on a 91 xj chassis. dont know if it was a 4 banger or not. Also just changed the computer and still no luck starting
Any ideas anyone ? help appreciated. changed CPS harness today still no ideas
what actually sends the signal to the coil for spark? is it tied in with injectors possibly
Just a WAG (wild arsed guess) but might want to check the cam position sensor. Remeber reading about a no fire on 2 and 5 once long ago, but can´t bring it to mind again.
When you set TDC, are you sure you were on the compression stroke. I´ve gotten so I always throw a compression gauge in number one, when looking for TDC, I´ve been fooled a couple of times (with the thumb test) and tried to set it up on the wrong stroke.
great idea on the compression tester i was kinda thinking that myself. in case i was tdc on exhaust stroke.
as for cam sensor i just bought a whole new distro (napa $55)and no luck same thing.
totally stumped on why no spark on those 2 cylinders. did research on the computer and its for a 91 auto .. so its the right computer..
UPDATE Re: No spark on cylinder 2 and 5

Well, come to find out it was the wrong flexplate.. the distance between the CPS and flexplate was just a tad to far for the sensor to operate properly..
Motor now runs excellent..thanks