Mongo

Looking at the wiring diagram, I can identify the wire that has lost its sheething after cutting away the tape and old connector. The wire is brown and appears to run from terminal 3 on the MAF to MP IX. This of course being the main grounding location, and could explain the issues when hot. Perhaps this ground wire has a higher resistance when temperatures climb.

I have my new connector ordered and will be working on the wiring this weekend again.

borland

Before disturbing the ground strap and while your waiting for the replacement MAF connector, you could perform the suggested engine starter cranking voltage reading (measure voltage between chassis ground and engine block).

Bill Ball

We checked the the rear ground strap, resting voltage, and there was no difference direct from ground post to body or from end of unfastened ground strap to body. But we didn't get the car up in the air to check the engine strap. We could, but I'm not sure why you want cranking voltage. Wouldn't the current flow blow my meter?

borland

No, it won't blow your meter. You would only be measuring voltage, not current. This is another way to measure the ground strap resistance with a common multimeter. An ohm meter that accurately measures less than one ohm would be very expensive.

By measuring this starter cranking voltage across the engine and chassis, you will be determining the relative resistance through the engine ground strap. While the starter is cranking, there normally be some small voltage drop across the engine ground strap. If the voltage drop is too much, the starter will be hogging all the current and the voltage during cranking will be too low for the other engine mounted electrical sources like the sensors and fuel injectors.

So those electrical sources on the engine may not function properly until you release the starter or the cranking speed gets fast enough to reduce the cranking amps and decrease the voltage drop across the engine ground strap.

borland

The fuel injectors are not grounded to the engine, so scratch that. Looks like the MAF and throttle valve sensor are only ones grounded to engine.

Bill Ball

borland:

Sorry if my high school physics is failing me, but I still don't understand exactly what you want us to measure. Do we leave the strap in-place and use the meter to measure voltage from the body to the motor in parallel with the strap while cranking versus not cranking?

borland

Yes, measure the voltage across the engine block and the chassis. If you have a helper, you can do this with the multimeter probes while your helper handles the ignition switch. If you don't then, you would need some clips to hold the probes and place the meter near the windshield.

It would be a good idea to do this measurement before disturbing the bolts for the engine ground strap. With the ignition on, you should read zero volts across the engine and chassis. With the starter cranking, you should be able to read some voltage. That voltage is the voltage drop across the ground strap.

If you were to measure 3 volts across the engine and chassis, and the battery voltage is 8 volts (measured across the jumper post and chassis ground) while cranking, then the engine would only be seeing 5 volts.

Mongo

Whether or not the bolts or disturbed. It would still be more advantageous to get rid of a 23 year old crimp with aged, heat cycled wires attached to it and replace it with a nice new crimped terminal and fresh wires coated with DeOxit, or something for protection for the next 20-30 years of running.

borland

Sorry, I don't see it your way. You don't seem to know anything about troubleshooting.

It's your car and problem, so do what you like. I was just trying to help.

Mongo

No I greatly appreciate the advice. I don't believe I am having an alternator issue, but could still be grounds related. I never had to troubleshoot like this before so bear with me; although I have been doing it for the past 6-8 months with factory workshop manuals.

SharkSkin

Andy, that recommendation is a grounds test, not an alternator test.

BTW DeOxit cleaner has no protective properties whatsoever. They do offer a separate product that is advertised as a protectant but I think Stabilant is the best approach.

Mongo

Got it!

The DeOxit product you mentioned is the gold and it's included with the cleaner in a package from Radio Shack.

Mongo

This weekend will be the grounds overhaul while I wait for my MAF connector. If I am taking apart the wires going to the MP IX ground by cutting off the ring terminal and replacing, do I need a special wire crimper, or can my Home Depot one suffice? I will also be working MP VIII which is on the driver side of the rear section of the block, adjacent to IX.

Landseer

Redo them if they look like the solder joint is corroded. Careful, not much room in there. I used a torch in vicinity of fuel lines for about 15 seconds to melt the ring terminal solder, but handwrote a will first.

If you are using the solder-containing shrink terminals, then a cheap crimper will be ok to hold it all together for the soldering. Be careful.

Mongo

Wait, did you solder the ring terminals you bought from Napa? I have those same terminals in your prior pictures.