Bjbpe

Here in Wyoming we probably have more unpaved roads than any other state. While driving on one of these washboard beauties my car began to lose power. I returned home and found that the ignition coil had rattled loose and the cable and coil were toast. I replaced the defective parts so now I have all eight cylinders running again. However, the intermittent no-start is back. I suspect that I am going to have to repair/replace the fuse and relay for fuel pump again. While I am crawling under the dashboard what other parts/relays/fuses should I be looking at? Lots of stuff in this thread but I thought I would ask. It's no fun pushing these 79 year old bones into various contortionist positions.

marknsf

Thanks for the suggestions I’ve been following up on them, including going through the list from AO’s link.

The car is and early ’87 without DIA in the LH. I would like to update to ’88 EPROMs. Does anyone know here I could get those?

I've tried starting multiple times during the last couple of days, the engine started quickly every time.

The alarm is after market and it only disables the starter. I verified the alarm would not engage when the engine is running (a good thing) so I don’t think it is the problem.

Tasks completed over the last several days:

- Cleaned the red positive wires on the battery and cleaned and checked the negative battery cable. The cable is clean even under the insulation.

- As a test I checked the voltage drop across the negative cable with the car idling, the headlights on high beam, the AC on and the heater fans on full. The voltage drop was less than 1 millivolt. At the same time the voltage at the battery was 12.8 volts and at the front jumper point 12.73 volts.

- I checked the Temp II Sensor. Both sides measured 2730 ohms to ground with the engine cold which should be close enough to the 3000 ohm spec. The contacts looked fine. I sprayed the contacts and reassembled.

There are two items I’m putting off for the time being:

- Complete cleaning of the engines rear ground points requires removing parts of the fuel system. I haven’t worked on the fuel system before and the fuel lines are original. I don’t want to risk creating a fuel leak.

- I have not disassembled the CPS connector. I’ve had connectors for both Hall sensor and ABS crumble to dust when opened, the CPS connector might do the same.

Some things I know:

- So far the engine has never stumbled or cutoff while idling or driving. So probably not a lose connection.

- The spark plug was dry when it was removed it after the first no start and before trying the new FP relay. So there was no fuel in the cylinders.

- The first no start occurred when the engine was hot, the second time the engine was cold.

- If any of things I have done actually fixed the problem I wouldn’t know it since the starting has not failed again.


Based on what I’ve read I think the most likely candidates are the CPS, grounds VIII or IX, one of the ECUs or a short/open in the injector circuit.

If the problem reoccurs I have an inductive timing light, fuel pressure gauge, spare relays and jumpers. So I will be able to determine if there is spark and fuel. Some of the tests are going have to be done very carefully if done without disconnecting the battery.

For now I will continue to try to reproduce the problem.

Mark

BTW, the link to the ground pictures in the New Visitor threads no longer works. The pictures were on another site and have been deleted.

John Speake

I can supply DIA MY88 EPROMs for LH and EZK, but anyone with a Sharktuner and an EPROM blower can make you a pair using 27C256 EPROMs. The default LH file in ST is based on the MY88. EZK S4 is one of the options on ST.

Randy V

It is unlikely that the factory alarm was disabled, unless you did it yourself.

marknsf

I didn't think the car had a factory alarm but I went back and checked the options and it has M533. It also has an added after market alarm with a remote which unlocks the doors. There are two relays mounted next to the air pump filter behind the radiator one is a black square and the other is a round silver can. There are lots of wires and I've been reluctant to try to figure out where they all go.

Is there and easy way to jumper the EZK disable?

I ordered some 27C256s and Bill Ball says he has a programmer. I found a download for the '88 LH at the 928s4.com but it does have the '88 EZK.

Thanks for the info guys. Learn something new everyday.

Mark

WallyP

Two prime suspects for electrical problems on a 928:
Aftermarket alarm system.
Aftermarket stereo system.

John Speake

I can email you the '88 EZK bin file if you email me.

marknsf

I’ve been researching the forum concerning the factory alarm (now that I know my car has one). The factory alarm has jumped the top of my list because cycling the battery connection would affect its state, one of the symptoms I’ve observed.

The after market alarm’s remote locks/unlocks the doors and when the alarm is set off the starter is disabled. The alarm system can not be enabled/disabled from the key locks.

Since the aftermarket alarm disables the starter I think the best thing to do is jumper 15 and 87a as this will jumper the EZK relay in the factory alarm. Is it possible to identify and get to these wires without removing the glove compartment and other pieces, maybe near the CE?

Trying to remove the after market alarm is likely to cause unexpected problems and the remote unlock is convenient. Besides if the factory alarm is defective removing the after market alarm would not solve the "no start" problem.

Thoughts?

John thanks for the EZK binary offer, I sent you a PM.


Mark

Mrmerlin

well its rather time consuming to remove the non factory alarm,
it involves taking your time and carefully inspecting where the extra wires are spliced into the factory harness,
then figuring out what you have to reconnect, there will be atleast 6 wires to remove.

Its a great idea to remove these systems as they cause issues years after they were born.

You sound pretty savvy so this task is something you should be able to handle.
as always,
make sure you have the battery disconnected while working on any electrical system in the 928

marknsf

No start problem found! Finally had the no start problem reoccur.

Since my prime suspect was the factory alarm disabling the EZK, I pulled the EZK relay on the CE and checked pin 86 which should be 12 volts when the key is in the run position, it was 0v. I then jumpered pins 87 and 30 on the CE EZK relay socket and was able to start the car. I replaced the EZK relay and installed a temporary jumper between B23 and F25 on the CE panel connectors since they were much easier to reach than the factory alarm itself. Again the car started with no problems. When the jumper was removed the car would no longer start.

So clearly the problem is the EZK enable relay in the factory alarm. This could be because the relay is bad, some other part of the factory alarm is bad or the after market alarm is causing a problem with the factory alarm. It really doesn't matter since jumping the alarm's EZK enable relay will eliminate the problem.

I plan to place and label a permanent jumper between the yellow wire to CE connector F25 and some convenient bus 15 location.

I would like to thank all the people who provided suggestions which helped narrow down the search. Special thanks to Alan and Randy for convincing me my car really does have factory alarm.

A big thanks to Alan for his "Wiring Diagram Primer", I'm looking forward to the full book. Also to John Speake for providing a binary to help me update my ECUs to DIA. Any ECU diagnostic would have shown immediately the ECUs weren't powered.

I know for myself and I'm sure many others this forum, its members and sponsors are what makes owning a 928 possible. I can't imagine being able maintain one without them and there would be far fewer 928s on the road today.

Now I can finally get the my 928 out of the garage with a reasonable chance of getting back :-) Oops, it finally raining in California :-(

Mark

Randy V

Good for you - happy to help.

John Speake

Good work Mark, I like happy endings :-)

dr bob

Great new, Mark! Kudos to you for figuring it out, and for sharing the diagnosis and results. Each 'adventure' like this adds to the community collection of puzzle pieces. Hopefully the puzzle will be complete within my ownership lifetime. One piece at a time...

M. Requin

I agree with Stan, you do sound savvy and well capable of returning the car to its original state and therefore should, so although I hate to add to the rain in CA, do not ignore those fuel lines at the aft end of the engine! Not paying attention to them is not preserving them, and the price for the former is dire. My U-shaped line looked perfect, broke completely in half on removal, pleanty of stories like mine here on the list. But kudos for tracking down your electrical gremlin!

marknsf

Thanks Martin. Yes, fuel lines are definitely on my list. I had a PPI done and they are ok for the moment.

When I got the car it was is in fairly good cosmetic condition but a there was a lot of deferred maintenance. When the "no start" problem occurred it was my first drive since finishing the TP/WP job which hadn't been done since 2000!

So soon.

Mark