With our latest dump of the wet and cold white stuff my mind wandered toward winter projects this morning and the question of rebuilding the LH brain.

My car performs well (I think, only ever compared it to a Testarossa, see thread) but do realise that components are +17 years old and may have reached or exceeded life expectancy and as such may require refreshing before the 'headstone' is ordered.

I'm looking for input re. rebuilding the existing LH brain vs buying a 'spare' vs doing nothing..............you out there John Speake?

 

No-one got any comments?

Perhaps the big 3 can comment on shelf life expectancy of the 'brains' !

 

Rich at Electronik Repair will rebuild your unit for ~580USD. My LH had been rebuilt previously and was dying--I had a rich idle and poor gas mileage. I swapped my LH for a rebuilt unit at Sharktoberfest, and saw much better idle conditions and improved mileage. I've never heard of anyone having their LH rebuilt just because it was old, but if you've run out of other things to do, well, then go for it.

Talk to Rich about the process he uses versus other rebuilders. I don't believe all rebuilds are created equal, although I don't possess the technical acumen to back up such a statement.

 

If it ain't broke, don't fix it.

 

The ready availability of spares and services locally is somewhat less than in, say, California. With that in mind, I picked up a '91 GT LH & EZK (ebay for a whopping $155), a new MAF for less - and a used MAF for far less.
I understand the LH death spiral to be more a longevity issue than usage - excusing voltage spikes, etc. - so playing the odds, should my LH die, I have a statistical 3 years of life/test unit availability in hand ( ref. an '88 S4). This unit has already proven its worth by keeping Jeffs '89 on the road this summer while we had his LH rebuilt. Similarly, I stuck the 'used' MAF in his car with success after demonstrating that his original MAF would not allow my car to run.
Conclusion - it cannot hurt to have certain spares available: you never know when they may be called into service - and are just the trick for trouble shooting. As for shelling out 5-6 bills on a LH in a premptive move, I'd be tempted to wait until it dies: the lay-up time to get a replacement is mere days.

 

Brian..............thanks for your resonse. My car is barely getting 400kms per tank and does have a unstable idle, at times. Nicole has posted getting 400 miles per tank............is there that much difference between foot pressures?

Its not that I've run out of things to do but rather being proactive vs reactive (dead at the side of the road) and I do somewhat posses the technical aspects hence my hope of a response from Rich/ John S et al.

 

Rich at http://www.electronikrepair.com/ has more knowledge in his brain about LH units...... and to boot, hes a really nice guy, really helped me out-twice....here is his email address electronikrepair@earthlink.net tell him Kyle from Erie pa sent you.

 

Malcom,
You're bored? Need something to do?
There are those of us without the means to even consider a Testarossa who would gladly sacrifice our left (fill in the blank) for an SC kit.

 

Ernest............once the GT is procured and updated with all goodies perhaps I'll settle down including the SC kit approx 30 years from now.

I'm still to young in my 48th year to be bored.............as they say back home.

Lang may yer lung reek!

 

I agree!!!! Especially if you are planning on buying a spare and fixing that one. There is a good chance you LH will never fail. You MAF on the other hand does have a life span. Maybe replace that first, before rebuilding a fully functioning brain.

But at the end it's your $$$$!

You don't need 30 years to get an SC...... The winters are long in AB, so build one!

 

Malcom,

I have a problem with my S4 too... it is running rich and stinks at the rear. I will post a link in the forum. In the meanwhile, my suggestion to you is to contact Rich from Electronik Repair. He is really nice and knows his LH stuff inside out. Talk to him, the worst that can happen is getting an honest diagnostics on your car.

Sincerely,
Khaled

 

As many have said, DON'T waste your money on a LH rebuilding if your engine
runs fine. The key problematic issue with the LH unit is overvoltaging the result
of; a charging of a fully dead battery via a strong charger, or an overcharging
alternator. Some rebuild their LH units when it's not necessary, thinking it's
the source of a running problem when it's not.

Check here ( www.systemsc.com/failuremodes.htm ) for info on 928 ECU problems.

Bottom line: There're many 928s running with their original LH units without any
problems!

 

Hello Malcolm,
The best thiug you can do is to get your LH checked out with a repairer who has a test jig. Then you will know if the problem lies there or not.

All the evidence is that LH ECUs will eventually fail. This is time dependant, not mileage. This week I rebuilt an LH from an '89 car with 23,000 miles on it. It is true that abuse can also shorten the life.

I do have people who have their working LH ECUs rebuilt as a precautionary measure.

BTW I charge 450USD fro a full rebuild.

Regards

 

The 35 pin LHs (Porsche, Volvo, Saab) that use a custom hybrid circuit are failing at a higher rate than other ECUs (L-Jets, 25 pin LHs, Motronics, etc). I've seen failures in low and high mile cars - and have had several customers opt to rebuild their LH before it dies on them. The LH can die at the worst possible time and can ruin a trip as you wait for a replacement.

I do not advise buying a used 35 pin 928 LH as a spare. It can die sitting on the shelf just as it can die when in the car. I had a customer that bought a used LH and six months later it was dead.

 

Thanks Rich and John..............my biggest fear is that my 17 year old LH brain decides to die on a very lonely stretch of highway, no cell phone coverage, the CAA hours away and grizzilies for company.

Can you advise want entails a full test on a 'jig' and the required updated and repair dependant on status.