shiva1

I haven't posted in quite awhile but back then my car was showing signs of thrust bearing failure (engine dying at stop lights etc.) Since then the problem is consistantly remedied by disconnecting then reconnecting the battery ground strap. After this the car runs and idles fine even with a warm engine. This seems to fix the problem for a few hours of driving, but sometimes, usually after driving the car a few times (highway and city) The idle problem reoccurs. The common factor seems to be the LH unit. I had it rebuilt last summer and installed it myself. Seemed like a straight forward installation. Could I have damaged or loosened some of the wires behind the LH/EZK mounting frame? Should I have the LH unit checked? It's just a hassle to not know when the dreaded idle problem will occur next and have to stop, pull up the hatch and mess with the ground cable. Suggestions?

Landseer

Did you ever replace the ground cable itself? Its new, right?

dprantl

The fact that the problem is cleared for a while when you disconnect the battery for a while definitely points directly at the LH. Easiest test would be to try your LH in someone else's 928 to see if the problem happens there too.

Dan
'91 928GT S/C 475hp/460lb.ft

Landseer

I think it points at the groundstrap and/or grounds. BTDT.
Or possible partial melt behind CE of defroster wire or similar into LH relay terminal wires.
Would definitely go thru that whole electrical core check first.
Alternately, CPS. On mercedes and audi, they fail with warmth / delta temp. Very possible here,too.

RED SHARK 1990

I had these symtoms before ,thought it was the LH, it was the hall sensor then 4 months later stalled at warm up and idle until the cps replaced. Try that...

shiva1

The strap is not new. It hasn't been replaced since Ive had the car 9 years

Landseer

We've seen a rash of these. If it has a little greying on the copper, its toast. Replace with a $7 parts store cable while you wait for the real one.

shiva1

Please explain hall sensor and cps................?

shiva1

Cable end is more of a brass color

the flyin' scotsman

What year is the 928?

The LH R&R is relatively simple, did you disconnect the battery when doing the work?

Newer than '87 MYs can run diagnostics with the proper equipment..........who rebuilt the LH? its probably under warranty.

Landseer

Hall sensor listens for engine knocking and makes a timing adjustment to protect it.

CPS is the crankcase position sensor that reads constantly the engine crankshaft position and tells the computer. CPS can make the car stall. Hall probably can't.

Change your groundstrap tomorrow. They take the car down intermittently. We had an S4 go down 3 or 4 weeks ago. I went out and rescued it with another ground strap. Don't bother looking for other symptoms until you do this, trust me. Cable tarnishes under the plastic shroud where moisture gets trapped, sometimes an inch from the body side, sometimes an inch or two from the battery side, either way, under the plastic.

the flyin' scotsman

The hall sensor is part of the ignition system mounted on the passenger cylinder head; it retards the ignition when theres an issue but shouldn't cause the stall.

The CPS is the crank position sensor and is located under the MAF at the rear of the engine block. It gets super heated and its cable/connecter deteriorate after time. Possibley cause the stalling issue.

Landseer

Crazy isn't it? Little stuff taking it down. That's the beauty of it. Guys get frustrated and punt. We buy them.

shiva1

I'll try a new strap. If that doesn't do it, I'll cal the LH rebuilder-he gave me a 5 yr warranty.

Landseer

No, not the right route.

LH is likely fine. You've not serviced the groundpoints on the car that the LH uses to operate.

Highly likely not the LH fault.