GUMBALL

Just purchased the car a couple of months ago, and am going thru the "resurrecting" issues (the car had been parked for 2-3 years)

The car had developed an issue where it would be idling, and just "shut off", but would re-start immediately. When I would engage the starter to re-start it, I noticed the tach needle would swing full field (unusual)

I checked and cleaned all the grounds (that made it a little better)
Replaced the MAF with one from Rich at ERI (which made it a LOT better)
It then ran fine, but I noticed the idle (warm) was 400 RPM - a little low.

But now, on a drive today, I have the similar symptoms again - I noticed that it had "stuttered" a couple of times while on the highway (70-80 mph)
then, sitting at a stoplight, it just "shut off" like I turned off the key. But same as before, it would re-start instantly, but again, the tach needle would swing on engaging the starter. It would run fine, accelerate properly, drive like normal . . for 10-15 minutes, then repeat.

I do not want to start "throwing parts at it", but not sure where to start - fuel ECU??. . ignition coils?? . . fuel pressure regulator?? . .

Any suggestions would be MOST welcome . . .
.

Speedtoys

Top end refresh, git er done. And the 14pin refresh.

AND you're close...join us!

https://www.facebook.com/groups/400240050086850/

MainePorsche

EZK sends signal to tach. Same signal also feed LH to prime/fire injectors.
Also consider CPS, and its effect on the EZK.
EZK relay would be an easy first look if can be swapped for testing.

Mrmerlin

I would replace the 3 running relays, do one at a time,
if the computers have not been rebuilt then now is a good time to have that done,
BUT do the relays first


https://www.google.com/url?sa=t&rct=...-ciFMIL7g877sw

GUMBALL

Next step:

I have replaced the 3 relays - EZK, LH and ignition.

Took it for a drive today, it seems to run well and power seems normal. (still idles at 400 RPM)
Idling at a stoplight, it just "quit" again - exactly as before, like you turned off the key. Re-started immediately and ran fine. And like before, when engaging the starter, the tach would swing to full field.

Reading another post, there was discussion that a tach problem would "shut off" the LH computer . . . is it possible that is what is happening here?

Or, is this issue something that a failing LH computer would cause??

MainePorsche

Sounds like your close to Speed. Make a contact with him. See if swapping in known good computer units mitigates the issue. If you need a new/rebuild control unit, so let it be done. I would also do a complete intake job too. Your ground points (8 & 9) are the two bolts that hold the throttle cable pulley to the engine block deep down under the MAS. These ground your EZK and LH. Also your CPS harness connector needs a look at. It often is in bad shape. Lots of heat and soiling at the bottom of the 'V'. Some say they can service the grounds without removal of the intake, but I find that a chore. After sitting for so long the wiring do the controller grounds may need surgery, not just a scrub and deoxidizing. First time I was there after I got the car the wires did not look like copper at all - they looked like bone. An ISV issue could cause a stalling too. I would just do the full monty.
Best wishes with the work.

http://dwaynesgarage.norcal928.org/1...%20Refresh.htm

GUMBALL

ISV ???

James Bailey

idle stabilizer valve....controls idle speed. It is buried under the intake

Speedtoys

...a big part of that top end refresh that -must- be done to begin to stabilize the operation of the car.

Many tiny little issues will revolve around the top end refresh.

GUMBALL

The next step in the ongoing battle - replaced the LH ECU with one from Rich at Electronik Repair in Mesa, Az. The engine immediately sounded better - cleaner, better taking the throttle, and better power. Obviously it was "time".
Over the past week of normal driving, the car performed very nicely, and I was beginning to feel that I had found . . "it" . . then the engine stalled again.

But, THIS time, I had the hood open. I heard a "gasping" sound (or a "vacuum" sound) which seemed to initiate the stall. It did not want to immediately restart. I disconnected and reconnected the battery, and it started immediately, and ran fine.

Suggestions Please ??