Mrmerlin

With Bill B assisting you, things will turn out well

Bill Ball

Thank you Stan. I'm not all that confident yet, but we will plug away at it until we find the problem. I'm still working on getting my car to pass smog.

newworld

I'm wrestling with similar situation to an extent. Start the car with maf unplugged...if car won't start or hard to start use carb cleaner in intake.

It's most likely not cps....my guess is maf....

Reason is I swapped my lh and get same thing.

I think the maf is bad.

newworld

Btw cleaning maf doesn't help....I tried that too.

On mine....
Hard to start...once started will start no problem. I can eliminate isv and tps as mine are brand new. I can eliminate lh as I swapped a good one. Once idle it runs better and smoother with maf unplugged. If maf is plugged in...idle is all over the place and I have to throttle it to keep it running and after throttle it wants to stall.

Very rough running with maf plugged. Now I did not run it with air box fully clamped down. But I think maf is a problem with these cars...

newworld

With maf unpluggled it will idle nicely at 500 to 600 rpm, but if you throttle it it will stall.

SMTCapeCod

Hanging thread..how'd this one turn out?

16vsilverstreak

Yeah, I would like to know what happened too.

rluvsporsche

I too have the same problem. Although my has change and gotten worst over the 3 year span every time I take my car out from winter storage. Now my car won’t run and has no fuel pressure but my fuel pump checks out ok. I’ve done the following in the past 3yrs. based on forum (not rennlist) advice and other 928 owners.
Check Compression = OK
Check and swap temp 2 sensor
Replace spark plug.
Install a fuel gauge to see if we have fuel.
Replaced LH loaner
Replace EZK loaner
Replace the MAF loaner
Replace Hal sensor
Replace 14 pin connector
Replace fuel pump relay
Check all the ground points and wiring on the car
Check timing
Check the timing belt
Trouble shoot running issues using the WSM all of the symptoms jumping pins in the ECU’s.

MainePorsche

You've done quite a bit.
Status of the CPS and its wires/harness ? Signals from it go to LH and EZK.
On the mechanical/physical side, status of the fuel filter. Clogged with varnish or other ?

jheis

On my car, the dieing problem turned out to be the CPS.

The distal (male) end of the plastic connector was completely gone - just three bare spade connectors sticking into the female connector. It was probably grounding out intermittently. A new CPS cured that part of the problem. As someone (Worf928?) explained - if the EZK doesn't see the signal it expects from the CPS it will shut things down.

Car still wants to stall sometimes when I come to a stop or back out of the throttle, so I need to replace the ISV. I've got a new one, but need to collect all the other WYIT parts that should be replaced when I pull the intake - so, in the meantime, I'm still running MMO through the ISV a few ounces at a time. Seems to work for a while. Puts out quite a cloud of white smoke on start up - probably good for mosquito abatement....

James

rluvsporsche

CPS check out good and wiring in good condition. I'm not sure condition of Fuel filter but it was replaced 30k ago some years back. I had fuel pressure after it stop running 7 weeks ago. The car run fine for 5 weeks early this year since I replaced the engine harness 14 pin connector but my idle was running high 1200.

MainePorsche

How did you check out the CPS ? Did you use an oscilloscope ?
Fuel filter - wouldn't hurt to change even if it's not the fundamental cause.

rluvsporsche

I didn't check the CPS myself it was a Porsche Master Technician he made a video of it but I can't find it. This is what he had to say "5 volt scale and a nice intermittent spike for the reference and the speed sensor was great".

MainePorsche

Great. That sounds like the Real McCoy.

rluvsporsche

I found the video but to big to upload.