I recently had my temperature gauge fail, and tracked the problem down to a bad wire on the sensor. I tried to splice a little farther up the harness, but in the end I had to splice onto the wire next to the gray connector at the firewall. Now I'm getting hesitation on cold acceleration. Is the gauge sensor connected to the ecu temperature sensor? Did I bypass some important wiring, or was it a coincidence?
No the gauge sensor is not connected to the ecu at all. But, the temp sensor the ecu uses is right beside the gauge sensor, you probably disturbed its wiring.
The wiring harness in and near the engine on these cars is a known weak point, and crumbles and deteriorates after awhile.
If you plan to keep the car, and want to avoid problems: have a new one installed, or buy a used one in good shape.
Dave Barton is reputed to be a good source of used harnesses, although I found and removed one from a car (a recent, new OEM replacement) from a wreck in a U Pull It.
You can replace it yourself (I did), but it isn't easy and requires some patience.
link to Dave Barton...
Thanks!
I'm dreading the inevitable harness replacement. I might just look for a nice '88 with a 5 speed...
I solved my hesitation problem with a good cleaning of the cap and rotor, so I'll pretend the wiring's ok for now.
The problem with your idea of looking for a nice 88 is that the wiring could well be shot on it, too.
It is endemic: over time, it will happen.
A bad harness can cause myriad problems, often intermittent and hard to troubleshoot.
The hardest thing about doing a wiring replacement is getting acces to everything; you'll need to remove the intake manifold; if you are comfortable in doing that, and have the time, you can do it.
They changed the wiring in '88, or was it '89? The newer cars don't rot. Still you can put an updated harness on an older car, or just rebuild the old one.
Don't count on an '88 having the better wiring harness. Ours didn't!
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