tempest411
NAXJA Forum User
- Location
- Discovery Bay, CA
Hello,
My '88 XJ has been giving me fits since late last summer. Initially it would stall while driving down the road, but would start back up right away. Changing the CPS did nothing to effect that. Then I noticed that when the engine stalls, as inertia is still spinning the engine over I had a tach signal, so I thought I therefore must have ignition, so the fuel injectors must not be firing. As the CPS was new, and wired straight to the ECU 20 years ago when I first got it, I suspected the computer. I suspected the fuel injector driver circuit must be on the way out. Well...two other known good ECUs didn't fix that:/ With a noid light on an injector connector I get a bright flash only on what I suspect is TDC #1. I didn't actually verify this, but the flashing is very consistent with a crank position it seems...and you can here the engine fire briefly when the noid light flashes.
What other failures might cause this problem? Even with a new Mopar CPS, it's output was always weak relative to the ideal quoted everywhere. I'd always heard it should be .5V or better, but the most I'd ever gotten was .25V. It ran for 20 years that way. I did pull the CPS out and drill out one of the holes to 3/8" and re-fit it. It did increase the output to .31V, but made no difference it now being stuck in front of my house...I started it a few weeks ago and it ran fine, but this week I can't get it to start at all.
Any thoughts? I'm tempted to start looking at the distributor, though every source I've come across says a failed pickup can cause driveability problems, but never a no-start.
Thank you for your advice!
My '88 XJ has been giving me fits since late last summer. Initially it would stall while driving down the road, but would start back up right away. Changing the CPS did nothing to effect that. Then I noticed that when the engine stalls, as inertia is still spinning the engine over I had a tach signal, so I thought I therefore must have ignition, so the fuel injectors must not be firing. As the CPS was new, and wired straight to the ECU 20 years ago when I first got it, I suspected the computer. I suspected the fuel injector driver circuit must be on the way out. Well...two other known good ECUs didn't fix that:/ With a noid light on an injector connector I get a bright flash only on what I suspect is TDC #1. I didn't actually verify this, but the flashing is very consistent with a crank position it seems...and you can here the engine fire briefly when the noid light flashes.
What other failures might cause this problem? Even with a new Mopar CPS, it's output was always weak relative to the ideal quoted everywhere. I'd always heard it should be .5V or better, but the most I'd ever gotten was .25V. It ran for 20 years that way. I did pull the CPS out and drill out one of the holes to 3/8" and re-fit it. It did increase the output to .31V, but made no difference it now being stuck in front of my house...I started it a few weeks ago and it ran fine, but this week I can't get it to start at all.
Any thoughts? I'm tempted to start looking at the distributor, though every source I've come across says a failed pickup can cause driveability problems, but never a no-start.
Thank you for your advice!