Eturbo924

Ok now we are getting some where. Had Paul (ZEUS+) over to go through the 928 with me. First I must say... he is a great guy.... now on to what he found. Have spark and power to the fuel injectors... but no pulse to the injectors. This is after the car ran and died.

He put put power to the LH relay connection and it made no difference. He tested the coils and they were good.

He did a bunch of other things... which he can comment on if he sees this.

What we seem to have decided is that the LH is definately kaput. We were trying to decide if there was anything else that could shut the computer down or ... if it is definately the LH? Could the cars alarm... if shorting shut the car down? If the fuel injector lines some how shorted... would that shut the car down?

Next week we plan to go over these last two items and then put my computer in his car to see if it kills his ignition as well.

Anyway thoughts?

Thanks again Paul. My kids say hi.

Eric

ZEUS+

Had a good time over Erics. When I got there the car had been warmed up. Eric started car and it ran fine. In less than a minute it shut down and would not re-start. Has good spark pulses, but no injector pulse. Made sure LH has power and Eric did a good job cleaning grounds. Just need to make sure injector wiring is not shorted, if not LH is dropping out. Ran out of time, be back on tuesday.

Louie928

Good chance it is a shorted injector wire.

ZEUS+

Started to get dark and cold here. I called him back and told him I wanted to check the wiring. He said that he had a problem with one and repaired it. He also told me that he checked all of them. I cant get over there until next tuesday. I am testing all wiring and connectors before condemning LH.

Eturbo924

The only strange thing about it being any kind of short...

The car is just sitting there at idle. It can run up to 40 minutes this way. Then all of a sudden die and not restart for hours... some times it will restart within a few minutes only to die within one minute (as Paul witnessed) and not restart until the next morning.

What normally quickens the process (but not always) is to run the car for say 15-20 minutes... get her good a warm. Then shut it down... walk away from it for 20 minutes or so and then restart it. Typically (but not always) it will quickly die.

Oh one other note. It runs like complete crap for 5 minutes or so when cold now. This is a new symptom. It runs like it has a massive vac leak. Missing and hesitation when cracking open the throttle. Then after the 5 minutes it clears and idles at 1100+ rpms. It also has started to try to catch itself. It stumbles down to 300rpms some times and sputters for a sec... then back up to 1000-1100 rpms. Typically before it would just drop rpms and die. So this is new as well. Maybe some of the other things I replaced (noted in above posts) helped if just slightly.

Just thought this would give more food for thought. Car seems to be running worse and worse... but trying to keep itself running more ("catching itself").

I will go back over the injector wires. I had found that the rear passenger side most injector harness had exposed wires (insulation was split) so I stripped it back and repaired that section. I do not recall any others with that bad an issue but I will check it again.

Tampa 928s

If anyone can find it it will be Paul.

I went through that on my 86 and my brothers 86.5. What I found after refreshing the intake and moving the injector wires it would die unannounced. I chased this for a while all the wires looked good. I decided to cut open the injector boot and found the wire insulation crumbled. When it would heat up or while running they would short and take the whole injector banks down, they are in parallel. The only way is to cut them open and look or if they are running move them and see if it stalls. I purchased a set of connectors with pigtails off of e-bay and that was that.

Tampa 928s

I heard about the condition of your injector wires under the boots. Just a note, once you remove all the connectors remove the LH connector and relay and if you have an open between the injector pins the short is gone. You can connect your meter back to the LH from the injector connector to check for a good circuit, should show a short if the wire is good. As Paul said a temp fix to see if that is the problem go to your local auto parts store and get some liquid tape and put them back on. If you start you found your problem, go ahead and order replacement with pigtails make sure they are the correct ones.

Eturbo924

Ok they were all bad. Now that is not to say I could get any of them to short. But every wire either just outside the rubber boot or just inside had its insulation cracked and wires exposed. So they could have shorted. One was particularly bad in that the wires had frayed.

Again... I could not get them to short.
Also note my car would restart after sitting. Then die again later after running for a bit.

So. I went ahead and cut everyone of them out. I cleaned them all up provided insulation where needed and soldered them back in and used shrink tube to properly shield the wires from eachother and anything they could short against.

Put it all back together... and no change. The car starts... runs kind of poorly... surging a bit here and there. If you hit the throttle too hard when warming up it coughs and chokes (must have a bad vac leak I figure).

So once it is warm it is ok... not perfect but runs smooth enough. Then maybe after 1/2 hour it dies.

It seems to recover a bit quicker lately. Well it allows a couple more restarts after it dies but after about two more deaths it dies for good and will not restart for hours.

So... think it is time for the LH computer. It will be swapped into Pauls car Tuesday to get the final answer.

Wife had hoped it would be ready for her Reunion on the 2nd / 3rd. Maybe ... maybe not I tell her.

Eturbo924

Ok pulled the LH to get ready for tomorrow and test in Pauls car... found some thing interesting...

The LH seems to have been rebuilt before.

It has two white stickers across the removeable panel on the back saying Guarantee Void if Seal Broken." There are also obvious signs that the cover was off before these seals were put on. Not a factory looking seal in other words.

Does this point to a specific company? I know one rebuilder has a 3 year Guarantee... though I am sure my luck is that this unit is 3 years and 1 day since it was rebuilt.

That is... if this turns out to be the problem.

Anyway... does anyone have any information I might be able to use to track whom rebuilt this?... if there is even any way.

Louie928

If this was an LH rebuilt by John Speake, it should have a label on the cover identifying it as a JDSPorsche rebuilt unit as well as 3 of the seals over the cover joint. If it was rebuilt by John it is highly unlikely it has failed.

Eturbo924

I do not think it was Johns

His rep is great ... Paul speaks very highly of him and that is good enough for me.

I will take it off and see if it shuts down Pauls car tomorrow night.

Issue is I need to run it in my car for a while to warm it and have it fail. Question... do I need to create a ground line to the frame from the mounting bracket for the LH to be properly grounded?

Thanks

Eric

Louie928

No. The LH and EZ-K grounds are handled through the wiring harness.

davek9

This almost sounds like the issue Paul in Saginaw his car would run great then the injection would just stop. Please don't start stripping injection wires ! You can test them for a short at the main LH connector inder the dash (I think that was already said here but want to restate test from under the dash first.

Does you car have an Automatic??? If so pull the Auto Kickdown Relay and see if your problem goes away. Ask me how i know

DaveK9

Tampa 928s

You may want to open the Lh and make sure your chips are seated correctly and no corrosion is present. Make sure you are grounded, open the box if you remove the chips be very careful not to bend the pins. a little up pressure on both sides wiggle out. It could be the chip is not seated since it has been rebuilt also check if it is a factory Eprom and not an aftermarket.

davek9

Als olook for crosion in the LH cable connector, like this on I saw on Saturday.
All the injectors were clicking and it would not start.
It cleaned up nicly but still did not work, I think the corosion my have shorted it out.