Fuel Injection Brain Info

Fuel Injection Brain Info

>FWIW, I just had the LH unit, commonly called the fuel injection brain.
>replace in my 87S4. Someone, I think it was Gulf Performance in Ft.
>Lauderdale told my mechanic that if the battery ever dies in a 928 you
>should disconnect the battery leads before charging it or you could
>possibly damage said LH unit in the process. Seeing that they cost
>anywhere from $1100.00 to $1600.00 plus labor etc. I thought I'd just
>mention it here. Perhaps Dave Roberts, Wally Plumley, or some of the
>people from Devek or 928 International would care to comment on this? If
>true, it might save someone enough money to have a pretty good night on
>the town.

>Gene O'Rourke
>87$4 5sp

Most definitely a problem with the '87-'88 model year according to the good folks at Zims. Seems to be one of the most frequent repairs to these sharks at this time. Most of the time failure can be associated with charging or even jump starting. Mine was replaced by the previous owner with a "remanufactured" unit from Porsche carrying a 928.618.123.LX part number at a cost of $1,093. Time and mileage may also be part of the failures.

Adam Spangler
'87 928 Silver
'94 968


I recently had first hand experience with this problem, as my 89S4 LH computer died on the way to the DC Frenzy and left me stranded on the side of the road for the first time ever in over 10 years of 928 ownership. (thanks again to Brian Robinson who graciously offered me his "brains" so I could get back home)

After my LH failure a few of us have done a little research concerning the LH-Jetronic Computers and every computer failure that we have seen so far was due to a flaw in the construction materials used by Bosch, not from charging a 928 battery with or without the battery hooked up.

What is happening is the main Bosch proprietary Integrated Circuit is failing due to what I feel is very poor manufacturing. The integrated circuit is made with the internal components exposed and then the IC is filled with a "rosin" to protect the internal components. Unfortunately the rosin that they selected is shrinking and/or expanding with changes in temperature over the years and finally cracks which also cracks and damages the internal components of the IC in the process.

So far Bosch is not being very cooperative in currently supplying anyone with replacements or diagrams concerning the IC. There are a few companies in the US who have some of the original ICs available (while they last) and are using those to rebuild the units. We are also talking to a few people who are going to attempt "reverse engineering" the IC and then making a properly built replacement.

It is my understanding that Porsche only offers Factory Rebuilt LH computers for 88 and earlier 928s, 89 and up 928 owners have to buy new ones $$$$ or have them rebuilt by one of the 2 or so independent rebuilds that are available.

I feel this is going to become an even more common occurrence as the "Fleet" ages and as I mentioned above a few associates and myself are looking for a proper solution.

David Roberts


Bingo! Dave, you may remember a few months back I was hunting for a replacement brain for my MY91 S4. The brain cut out completely when I went over a 2-3" pothole; not a jump start in sight. The IC must have cracked with the shock.

Julian Macedo
89 (MY91) S4 auto baltic blue/linen


[24 May 1999]
Programa, in Boca Raton, FL, 800 668-8843 advises that they have stopped repairing the 928 LH units because Porsche stopped supplying the chips for it. They are working on developing their own chips, first for Volvo, (because of the volume), and then for the 928. They estimate it might be ready in about two months. I'll call them back then to see how it's going.

Don Burrows
87 S4 A/T


[12 Aug 1999]
I just talked to Scott at Programa who said the 928 LH chips should be available in one to two months. They are finishing the Volvo chip which is similar. He said the estimated cost for an LH brain rebuild will be from $390 to $410.

84S ruby red met
87S4 blue met

[Editor's note: I'm pretty sure that the whole Programma thing never worked out. Too low of a potential sales volume was the reason I heard.]


Just spotted in the Porsche news group: [November 2000]

Subject: Porsche 928 Remanufactured Fuel Injecion Bosch LH2.4 Ecu

ATP Electronic Developments Ltd have re-introduced their range of remanufactured Bosch LH2.4 ecu`s.

For availability on part numbers and prices contact our sales desk on 01543 467466.


[December 2000]
It has has been several years since we have been able to have the 928 S4 brains rebuilt affordably in competition with Porsche. A very specific chip set that goes bad had became unavailable and we were unable to have these brains rebuilt.

Right now we were able to obtain a shipment of chips and can again rebuild these units. We are charging $495.00 with a $200.00 core charge and a 12 month warranty.

We have already shipped one brain, and have only one other rebuild unit in stock, after that we have no other cores. You can purchase this unit or send your broken unit in for rebuild. Because of the problems we have had in the past with availability of chip sets I recommend that you jump to the head of the line if you are needing a brain or just want to stock an extra one.

Part Werks of Chicago

[February 2003]
Someone recently posted on RennList about having a very bad experience with an attempted brain rebuild by the above source. So, until the situation changes it is probably wise to look elsewhere for a solution. --Editor

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