Full Version: ECU Repairs
Anyone have a source for rebuilding the ECU units? Fuel Injection Corp no longer does them.
Check with Jeff Bowlsby. I believe he now has the equipment.
I think Jeff can test them, but I don't think he offers rebuild services.
They are apparently overbuilt, but they can and do fail. I've got two ECUs that were rebuilt that failed, and I recently bought a NOS one that had never been installed that was bad right out of the gate.
Based on what I've read from Dr. DJet, I don't think I'd trust anyone to rebuild them other than Bosch. Unfortunately, their classic car rebuild services don't seem to be offered in the U.S.
You may be better off looking for a known good ECU which will probably be cheaper than having yours rebuilt.
They are apparently overbuilt, but they can and do fail. I've got two ECUs that were rebuilt that failed, and I recently bought a NOS one that had never been installed that was bad right out of the gate.
Based on what I've read from Dr. DJet, I don't think I'd trust anyone to rebuild them other than Bosch. Unfortunately, their classic car rebuild services don't seem to be offered in the U.S.
You may be better off looking for a known good ECU which will probably be cheaper than having yours rebuilt.
I dont repair ECUs, my equipment is the interposed shop testers from Bosch and EFI Associates for diagnosing D-Jet and L-Jet systems while mounted to the car.
Google ECU repair, I have aheard of a few places that do this over the years but never had a need to pursue it.
Google ECU repair, I have aheard of a few places that do this over the years but never had a need to pursue it.
I'm not sure if he does them but but Loren at Systems Consulting has been repairing Bosch CDI and FI units for the 911 groups for years...
https://www.systemsc.com/
https://www.systemsc.com/
PCB board repair is straight forward but also very scary for those not used to doing it.
ARE YOU SURE IT IS THE ECU?
I would very closely ring-out the cabling = from the board to the various components. I bought 3 of them and one did not work in my car - there was a wire problem on the inside. Mr. Bowsley does a fantastic job at building new harnesses - if you have open wires, he can save a great deal of time.
The unit itself is not a computer as we now think about computers, though there are some logic gates built within using discrete components (transistors) and for 1966 (most likely the year the engineering started at Bosch) this was as close to a computer as automobiles would see for a few years. The device is over-built by a bunch. So ground loops and large differential voltages imposed by broken wires and polarity goofs are survivable. (No guarantees on that one) . This system uses timing signals to generate squared wave pulses for the injectors. The timing is introduced by the distributor and the duration of the pulse is determined by pre-calibrated references that measure voltage differentials from various sensors. The machine keeps no state, is hardwire programed with one exception and that is a single potentiometer (might be a varistor) that can adjust richness pulse width.
The non-working one that I bought was in an engine fire and survived the heat/water and then years of sitting. My guess is a wire was broken when it was taken apart since I bought it already in pieces.
When I debug old systems like this I focus on the power circuits. the 12V source and how it is distributed and powers the unit. In the very old days I would fix TVs and Radios (I was an Electrical Engineer - still am - and all of my older relatives would expect me to fix their TVs) near always the problem was a capacitor in the power supply. They fade and then fail from heat. Where there is power there is failure.
In the ECU, I would start looking for burn marks on the board, where due to miswiring or other goofs an over current condition is introduced, creating heat and then failed circuitry. If there are areas like this clean and re-solder any broken traces or wires. Next, learn how to test transistors and diodes and check all of them. There are lots and this will take a while - also testing them WHILE they are in the circuit takes some skill......do what my kids do: watch a you tube video.
Unless you have an ECU that is a parts source, getting transistors and diodes that are of the same electrical spec is simple, there are cross reference sites on the net. read the number and select a new component - it will be much smaller, different case and most likely more reliable. But will do the job.
Not sure if this is helpful, however, I felt the need to write this, happy to adjust this note if you have different opinions.
Thank you for being here, this site has resulted in a great car and an unbelievable bonding experience with my 19yr old son,
CTC911CTC
I dont repair ECUs, my equipment is the interposed shop testers from Bosch and EFI Associates for diagnosing D-Jet and L-Jet systems while mounted to the car.
Google ECU repair, I have aheard of a few places that do this over the years but never had a need to pursue it.
ARE YOU SURE IT IS THE ECU?
I would very closely ring-out the cabling = from the board to the various components. I bought 3 of them and one did not work in my car - there was a wire problem on the inside. Mr. Bowsley does a fantastic job at building new harnesses - if you have open wires, he can save a great deal of time.
The unit itself is not a computer as we now think about computers, though there are some logic gates built within using discrete components (transistors) and for 1966 (most likely the year the engineering started at Bosch) this was as close to a computer as automobiles would see for a few years. The device is over-built by a bunch. So ground loops and large differential voltages imposed by broken wires and polarity goofs are survivable. (No guarantees on that one) . This system uses timing signals to generate squared wave pulses for the injectors. The timing is introduced by the distributor and the duration of the pulse is determined by pre-calibrated references that measure voltage differentials from various sensors. The machine keeps no state, is hardwire programed with one exception and that is a single potentiometer (might be a varistor) that can adjust richness pulse width.
The non-working one that I bought was in an engine fire and survived the heat/water and then years of sitting. My guess is a wire was broken when it was taken apart since I bought it already in pieces.
When I debug old systems like this I focus on the power circuits. the 12V source and how it is distributed and powers the unit. In the very old days I would fix TVs and Radios (I was an Electrical Engineer - still am - and all of my older relatives would expect me to fix their TVs) near always the problem was a capacitor in the power supply. They fade and then fail from heat. Where there is power there is failure.
In the ECU, I would start looking for burn marks on the board, where due to miswiring or other goofs an over current condition is introduced, creating heat and then failed circuitry. If there are areas like this clean and re-solder any broken traces or wires. Next, learn how to test transistors and diodes and check all of them. There are lots and this will take a while - also testing them WHILE they are in the circuit takes some skill......do what my kids do: watch a you tube video.
Unless you have an ECU that is a parts source, getting transistors and diodes that are of the same electrical spec is simple, there are cross reference sites on the net. read the number and select a new component - it will be much smaller, different case and most likely more reliable. But will do the job.
Not sure if this is helpful, however, I felt the need to write this, happy to adjust this note if you have different opinions.
Thank you for being here, this site has resulted in a great car and an unbelievable bonding experience with my 19yr old son,
CTC911CTC
QUOTE(JeffBowlsby @ Aug 6 2021, 11:21 AM) 
I dont repair ECUs, my equipment is the interposed shop testers from Bosch and EFI Associates for diagnosing D-Jet and L-Jet systems while mounted to the car.
Google ECU repair, I have aheard of a few places that do this over the years but never had a need to pursue it.
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