Bill51sdr

Wire harness issues on a 23 year old car?!? Surely you jest!

Mongo

My 2 wiring harness issues have pretty much been fixed, Temp-II and ISV harness. A nice solder on them was done and they are shrink tubed, and wrapped with electrical tape again over as a profilactic just in case.

I wonder if the LH is just trying to learn the car still like some of you said. Maybe if I drive it longer, hang some garlic and a roserie from the mirror the problem will go away.

SeanR

How old is the TPS? And is it making contact all the time?

Mongo

When I was originally having all of these issues I checked the harnesses I could see. The TPS is one of them. TPS is a year old as are all parts that were done during the intake service at the same time.

dr bob

Andy--

FWIW, I had a rebuilt box installed for less than a week when I had a really interesting idle issue. Just at the end of the driveway (~1/4 mile) from the garage, the car started surging a lot, on and off. Of course this was one of those rare times when I convinced K that we would take the 928, since the seats don't fit her well. Anyway, got turned around and back to the house, and took her 4Runner instead. Back to the point though, the easy "cure" involved disconnecting the battery for a while (like a few hours), then reconecting it. All the already-clean battery connections were re-cleaned and sealed up again after assembly, but those housekeeping issues were not given any credit. Anyway, the car has been flawless since.

Might be worth it to power the car down for a while, and force it to relearn everything again if the problem emerges again. It's cheap and easy, and can be completed even after a couple brews.

worf928

One last time and then I will shut up.

Have you checked the actual operation of the idle switch at both ECU connectors? Just because it's new doesn't mean that it works.

You can also check the operation of the ISV from the ECU connectors. You don't need a Hammer for either check.

Download:

http://928frenzy.org/docs/928_Periodic_Inspection.pdf

and look in Section 8 for directions of how to do this.

Last, if both the idle switch and the ISV are operating, and if your MAF hasn't been rebuilt, I'd send the MAF to Kevin at injection labs for testing.

Landseer

Mongo, guru of my favorite OT thread of all time.

I have only read your original post. Not the ones after. Forgive me if this is a repeat.

I have been excorsizing an 85 with LH.

So far, a terrible ground cable has been discovered. And a bad harness near the Temp II. But there's more.

I've had terrible intermittent run problems since the above.

Something to try.

Take a thin long screwdriver. Backprobe and Press each and every wire connection on each and every colored plug at the base of the CE panel to seat it. If you haven't cleaned your panel in a couple years, pull, clean, replace and do this.

It helped mine on three separate occasions to eliminate the random cut-out. In between, I messed with the panel in between and unplugged some plugs.

Now, no cut out. Let me know.

Landseer

Looks like Mr. Merlin had already posted an eerily similar suggestion...

https://rennlist.com/forums/928-foru...to-wiring.html

Mongo

I barely got home today. I stopped to meet my fiancee up for dinner and when I started the car (warm start) it would quit. The car had NO POWER all the way home. At idle it was at 300 RPM and I could see the ISV was struggling to save the car from dying. It runs perfectly fine when cold! Like **** when hot!


For the ****s of it I decided to unplug the temp-II sensor and try and start it. It started and stalled. Reconnected it and had the same results right now.

I brought up relays earlier, but I don't think this can be relay related, can it???

I don't know what to do...


I'm really considering selling now after putting a hole in the pocket the size of an LH. If anyone electrically knowledgable is in my area, I beg for help to diagnose this. I cannot drive this car far. I no longer trust it anymore.

Cosmo Kramer

Unplugging the temp 2 will just give infinite resistance to the LH, which won't help you much. You need to test the sensor with an ohm meter cold and hot and compare it to spec. Specs are engine cold, should measure about 2000 to 4000 ohms. (2-4k ohms). Engine at normal temp, 500 to 700 ohms.

Mongo

Just out of curiousity, is there a polarity on the temp II sensor itself. If I spliced and soldered the new harness in with the wires swapped to the connector, would this cause the same issue?

worf928

No.

The Temp-II is TWO temperature sensors. One wire for one sensor. One for the LH. One for the EZK. The ground contact is through the waterbridge bolts to the block.

SeanR

But, if the wires for the TempII are touching just before the sensor, you will have this issue. Pull the boot back and double check that. Happened on both of my cars.

Your best bet is to do the diagnostics form the LH/EZK connections, that way you know if you have the proper readings coming to the computers.

Mongo

I am starting to think more and more that this is somehow related to the Temp II if it only happens when hot and there is no problems with the car when the temperature is below 1/2.

When I did the splicing, I used shrink tubing over the solder to ensure that the connections wouldn't touch.

If each terminal on the temp-II itself is not pole-related, than could each terminal give a different reading to the LH and EZK?

This weekend I'll try and get the car hot, disconnect the LH and EZK and take some readings from the pins there when cold and hot.

SeanR

Mongo, you don't need to get the car hot to test the wiring loom.

If you are just testing the TempII, take the thing out and get a hair dryer.