[Argos]

I am restoring a 1984 Spider S3 and I have hooked up a battery and turned the key and nothing happens.

I am working on verifying all the electronics work and haven't gotten in too deep yet. I opened up the motronic unit and I do see a spot where the pcb is a little charred. Does anyone know what that round thing is? Its on the other side of where it is charred.

Is it worth repairing the unit? I have seen some people talk about using megasquirt or is that a rabbit hole not worth going down? Let me know what you think.

 

[Argos]

 

[Gubi]

Dude, the whole underside of that PCB looks pretty messed up. Was it sitting in water or something?

 

[FrassoFetta]

That is just flux from wave soldering. It is ugly, but pretty normal to find 80's boards that look like that right off the line.

 

[spiderserie4]

I am restoring a 1984 Spider S3 and I have hooked up a battery and turned the key and nothing happens.

nothing? meaning nothing at all?.... no crank, no dash lights.....as in zilch?

(if so, I'd hardly be blaming the ICM at this time...)

 

[Gubi]

That is just flux from wave soldering. It is ugly, but pretty normal to find 80's boards that look like that right off the line.

Oof. Maybe you’re right, but my Milano ECU did not look like that...

 

[Argos]

There definitely is a break on contact where the black soot is. Could possibly run a jumper wire across.

Admittedly this car was sitting at auction with the top down for probably a while. Things got wet but there is no sign water entered the unit.

According to the wiring diagram the battery only goes directly to the starter and to the fuel injection ecu. Then from fuel injection ecu to ignition ecu and then the ignition switch.

Is there an inline fuse somewhere that I am not seeing?

 

[Argos]

Looks like the round thing is a transistor.

 

[GV27]

I think you mean L-Jetronic.

Backup a step though - do you mean it cranks but won't fire? Or do you actually mean that nothing happens - no cranking? It should crank no matter what the status of the computers is. If it's not cranking you have another issue.

 

[Argos]

There was no crank, nothing.

 

[Argos]

Alright I may have something actually. Battery wasn't fully charged. Tried a new battery and im getting relay clicks now. Going to investigate more and retroubleshoot with new battery.

 

[DFit]

The brown spots and cracks visible on the back side do not look hopeful to having an operational board. Do you have someone with a similar car that you could plug your computer into and see if it functions?

 

[ghnl]

To clarify, the 1982 - 1989 USA Spiders (Series 3) have Bosch L-jetronic EFI. The 1990 - 1994 Spiders (Series 4) have Motronic. To make it more confusing, the FI computer in the Series 3 Spiders is labeled Motronic - the ignition computer is labeled L-jetronic (or is it the other way around...?). In the Series 4 cars the two computers were combined into one.

Click on the link in my signature to a page of DIY diagnosis of the Series 3 Spider's L-jetronic system. I do not know of any way to test the computers themselves. Even back-in-the-day, the instructions were to check everything else and if no wiring or sensor faults are found then the last step is 'replace computer'.

 

[FrassoFetta]

There definitely is a break on contact where the black soot is. Could possibly run a jumper wire across.

Admittedly this car was sitting at auction with the top down for probably a while. Things got wet but there is no sign water entered the unit.

According to the wiring diagram the battery only goes directly to the starter and to the fuel injection ecu. Then from fuel injection ecu to ignition ecu and then the ignition switch.

Is there an inline fuse somewhere that I am not seeing?

Ah! I didnt see the burn. Yeah that is just the ground plane though. It is connected to the bolt where the unit mounts to the chassis. There are other components below where the big transistor is mounted to the frame as a heat sink... I would investigate in there... Dont stress on the flux unless you have to re-solder.

 

[FrassoFetta]

I bet there is a regulator under there that has burnt.

 

[Lokki]

HOW WE DO IT

Porsche, BMW, Ferrari - We'll make any used ECU work - Send us your damaged ECU and we'll TEST and REPAIR your unit and send it back to you with our 5 YEAR WARRANTY.

www.ecudoctors.com

Although ECU Doctors does not specifically mention Alfa on their website anymore, they used to be the “Go-To” solution for Alfa Motronic ECU’s. Not sure about the Bosch boards. Noting they may be able to fix it or know someone who can, it might be worth the cost of a phone call to see what they say.

 

[Argos]

Ok thanks for the tips guys. Just had a baby and I am working a lot so I only get one day a week to work on this.

Don't know anyone with a functional board to test but I'll check under burn to see if something is fried and will attempt to repair it before I send it off for repair.

I'll post pics if I make progress on the board.

 

[spiderserie4]

forget the computor for a moment!

Alright I may have something actually. Battery wasn't fully charged. Tried a new battery and im getting relay clicks now. Going to investigate more and retroubleshoot with new battery.

Relay clicks are one thing, but if the starter is not cranking that engine over (and strongly at that!), you are wasting your time looking for iffy solder points in the ECU!

Get the car cranking strongly: a good battery needs to be 12.6 V static, and when cranking you need to measure at least 10.5-11V..........without that necessary minimum cranking voltage your computor won't work no matter what you do to it....
Check the battery ground cable bolted to the floor near the battery, remove the attachment bolt, polish the metal and put it all back with some copper grease.

Oh and congrats on the new baby

 

[Tom&RobsAlfas]

Given how many Bosch Spiders have rusted away and been parted out why don't you just buy another unit? How much could they be? Hint Hint...

 

[alfaparticle]

L_Jetronic is an analog system with separate fuel and ignition controls. Motronic is digital and as Eric posted they are combined in a single computer. According to Bosch, Motronic is a more complete engine management system as it computes optimum ignition advance and fuel throughout the driving range based on many sensor inputs.