Nicole

Is there a pattern of age and mileage when these thigns fail? Tell us when yours failed - how old was the car, and what mileage did you have at the time!

Should one cosider having them refurbished as a preventife measure, to avoid getting stranded in the middle of the desert at night?

imfinlay

Mine failed totally at about 101K miles in around September '05. It's an '89 S4 Auto. However, the car had not run terribly well in the 12 months leading up to that - rough idle, hesitant acceleration. A John Speake rebuild sorted it.

Ian

Drmark

Is the set up in a 95 GTS likely to be any different? Or just as prone to failure? My 87 S4 needed a John Speake rebuild at 93.000 miles and 18 years - poor idle and hunting were the first signs of trouble.
Mark

Tails

Nichole,

Mine failed after 15 years and just over 80,000 kilometres (last year).

From all my reading on the matter it is an age thing relating to the breakdown of protective coating on a hybrid tile fitted onto the LH ECU mother board fitted in later model 928 S4s, GTs and GTSs.

John of JDSPorsche had me back on the road within 18 hours of my notification by e-mail of a suspected LH ECU failure. This was quite a feat at I am 12,800 miles from where John lives, but he was able to arrange a loan LH computer from his agent in my home town. John is truely international in his operation and help he provides to us 928 owners.

Tails 1990 928 S4 Auto

Nicole

Hmmm... So if you had a 91 model with 90k miles, would you advise driving alone through the desert with the orioginal ECU, or have it rebuilt as a preventive measure?

Drmark

Don't be such a pessimist Nicole!

John Speake

Hi Nicole,
There is no pattern at all to LH failure. I've seen all years and mileages fail. There's no pattern.

I am seeing progressively later and later MY for rebuild since I started nearly 4 years ago. So there is a time element in there, I think.

Death of an LH may well also be hastened by the usually suspects - usually a heavy duty charger/starter (usually used by garages), igntion leads arcing, faulty alternator......there's a pretty complete list on page D24/28-3 in Vol 1-A of the workshop manual.

Ispeed

Mine's original. '87 with 115k miles and runs great/knock on wood.
I've been thinking about preventative rebuild like anyone would.

Nine2Eight

87 928 S4 - 17 years, 90,000 miles approx.

Joe C. - Seminole, FL

AO

FYI... Per my records, my '91 failed at 116k in June of 2003. Car now has 123k

heinrich

i've never had one fail

John Speake

Like I said - no pattern :-)

I've rebuilt one from an '87 with only 27k miles on it. I have known several that failed as someone drove over a pothole.

I am also getting people wanting them rebuilt as a precaution.

There was a theory that the encapsulation on the chips was failing, but I don't subscribe to that - exactly the same technology is used in the MAF electronics and I have not seen any failures in many hundreds of units.

My suspicion is that the usual mode of failure is that the chips are damaged by high voltage pulses on the input lines to the LH. But there is also good evidence that mechanical shock can also kill them.

Jerome Craig

My 86.5 had 225K when I sold it, never had an LH failure.

Mongo

She has a good point. It really sucks how the 928's LH is an Achilles Heel on the fuel injection system. I have not had mine rebuilt yet, but I'm willing to bet that it has already been replaced.

inactiveuser1228

45k miles and some time between 1992 and 2005