Paul Robles

hello 928ers,


I am in a bit of a hole my 928GT will crank but wont start.
Here are the symptoms:

1) turn key to on position to prime fuel pump (car sits a lot)

2) ticking sound coming from intake area (constant when key is in on position)

3) car cranks but will not start


4) cranks several times with only battery starting to get low, will charge
(battery full and try again)



this is new car usually is started every 2/4 wks , have read some older
posts that the LH is bad. I have had this car nearly 20 yrs and never heard
of that and have the battery replaced and charged many times over that
period could use some assistance before taking to my local dealer top
end refresh less than 6 months ago( intake & cam covers refinished pc
sliver/alum finish all new hoses,new idle stabilizer/from Porsche "expensive"
car ran fine but between 200/400 after back from shop drove and
started like normal, do not think there is any relation here. any ideas
or know what this is and fix would be helpful.

SeanR

Welcome to rennlist.

Yep, typical LH computer failure. They are all going to fail, it's just a matter of when. Contact Roger@928sRus.com and he will get you set up. He has 7 on their way back from England (JDS Porsche) as they have the best rebuilds.

worf928

Yup: Dead LH. And yup: it's just a matter of time.

I won't opine on who does the best rebuild, but Rich Andrade at http://www.electronikrepair.com also rebuilds LHs. From my perspective, the main difference is that Rich rebuilds YOUR LH and sends it back to you. Roger via JDS Porsche does an exchange.

Some folks don't care and some folks want the LH that came with their 928.

I have customers that have fallen into both categories and have installed both rebuilders results.

Chalkboss

That's it. My 87 runs great but has original MAF and brain. I'm going to put those on the list to get done. Seems like a good pre-emptive strike.

Paul Robles

Thanks for your info/answers,,, the car has been running for yrs with the same use
now this shorts out,, how can i be 100% sure. I have seen other posts here which
are old posts but state the same symptoms or similar issues with some finding
this an expensive repair but without solving the problem. I do not want to have
this repaired and not fixing the problem. I am sure that all of you understand what
I mean. In the past I would visit new car dealers just to throw parts at the issue and
not fix the problem any other info or things/areas to check before having this
replaced or repaired would be great to hear anything else regarding this issue.

worf928

OP, if you can't seperate the wheat from the chaff on this forum and can't diagnose the issue yourself, then have it flat-bedded to Greg Brown's Precision Motorwerks.

Also, to think that there is a 100% probability that there is only one thing preventing your 25-year old 928 from starting is not based on solid logic. You might indeed have two or three things that have conspired to cause this issue at this time.

One more thing: any of the above-mentioned Rebuilders, or any local 928 owner with an '87+ can test your LH for you. All you have to do is to accomplish removal. If a local is willing to travel you might not even have to do that.

UpFixenDerPorsche

Sorry Paul but your LH ECU has gone to electronics heaven. :-(

Been there done that.

Get one of John Speake's re-manufactured units. Better performance and far more electrically robust than the original. I 'know' thes
e things. :-)

I should have mentioned: the 'key' microchips involved are quite sensitive to over-voltage spikes that often occur during instant of connection/disconnection of poor quality battery chargers when attempting to re-charge a flat battery.

I found out this the hard way, but in hindsight the improvement given by John's re-built unit well overshadows the initial inconvenience.

Cheers.

jcorenman

Paul, the key symptom that you mentioned is the "ticking sound coming from intake area (constant when key is in on position)". That is a 99.9% certain indication of LH failure. But as Dave points out, one failure is no assurance that another doesn't exist.

In any event your LH will need replacing at some point, the "hybrid circuit" in the LH (a small ceramic circuit board) will eventually fail with age. This gets replaced by a proper PCB during rebuilding, so rebuild LH's are not subject to the same aging problem.

jetson8859

Had same issue with my 87s4 when I first got it. Went through preliminary steps like relay, relay, relay and she ran for about 2 weeks then back to the clicking and no start. Swapped out a good local unit and she fired right up so that confirmed the LH failure. Sent mine off to Louie Ott who extracted my original eeprom chip and dropped it into a JDS unit and 3 days later had it back and installed, no issues since and the car idles and runs smoother after the LH upgrade.

PR89928GT

thanks for all the response's I will check this out. A new one is has a retail of $2k!! What are the
rebuild costing and is there anyone in CA that is actually fixing them on site without farming out
the jobs. thanks again all!

worf928

Rich Andrade fixes them himself.

dr bob

I've had several done by Rich Andrade with so-far excellent results.

OP-- There's a very limited number of things that trigger the injectors at all. One is bad injector wiring, but that tends to cause them all to stay on or stay off. The clicking with no engine run is an almost guaranteed failure of the LH controller. If you still suspect it's wiring, just unlatch the connector on the LH and see if the clicking stops.

The good news on the rebuilt units vs the new is that new ones suffer the same problem as the one you have. It's just a matter of time. The good rebulds (Rich in Phoenix or John Speake via Roger) have ceramic replacement circuits that don't have the same interior corrosion issues as the factory pieces.

I'd been party to a few failures on others' cars over the years, and in the middle of all that managed to secure a failed controller to have rebuilt. Kept the original in the car just to see how long it would go. Like yours, the symptoms showed up after the car had been sitting a while. Obviously there's no guarantee that a car that was running fine when parked will run fine when restarted a day or a month later (as in my case).