Little Nugget from Steve Wong on ECUS, early Tachos and 3.2 Swaps

[ischmitz]

I would look here http://www.megamanual.com/

It’s an open source EFI project and has tons of information on how various algorithms determine fueling and spark timing. Lots of good information.

[917_Langheck]

Originally Posted by ant7

Interesting!
Any idea why it was limited to certain markets ?
Ant.

Certain markets responded to the oil/political scenarios of the 1970s and 1980s by requiring more efficient cars. One way to increase mileage and reduce emissions is to upshift early. Cars today still do that in the US. 1st to 4th shift in automatic cars is not uncommon. Some even do 2nd to 4th from a dead stop.

[wazzz]

Originally Posted by mysocal911

Datasheet - https://www.alldatasheet.com/datasheet-pdf/pdf/619872/TI1/ADC0808CCN.html

Vcc (+5V) is pin 11. Various semiconductor suppliers produced this part.

Dave, thanks. But I did download and browse the TI datasheet for this ADC before I asked this (probably) stupid question.

Here is what I mean; circled in red. No +5V power supply to pin 11, only a 4.7k pull down to ground.
All other +5V lines are pull-ups, except for VREF+ (pin 12) which is connected to +5V through a 0R resistor (again a strange 0R resistor labelled B11).

So how does that ADC IC get its power supply? Is something missing on the schematic?

[ant7]

That makes sense
Ant.

Originally Posted by zuch

I believe the up-shift light was added to the US market cars in an attempt to improve fuel efficiency. The idea being if you shift to a higher gear sooner you will burn less fuel.

[ant7]

Totally understand your frustration with the schematic, I spent many hours going over it when my own ECU started doing odd things, I did learn quite a bit, although I still have the issue with my original ECU the time spent did help me diagnose an issue I had with another ECU I initially got for spares, but managed to get it up and running, I also realised there are various mistakes!
Ant.

Originally Posted by wazzz

Cheers Ant,
Currently trying to decipher and understand as much as I can from the Motronic schematics. My circuit analysis ability has gone long ago and those schematics are not easy to follow. Trying to annotate them for reference.

Does anybody know why the ADC appears not powered? VCC is connected to ground via a 4.7k resistor. Or is it powered via VREF+ and VREF-?

I may open a dedicated thread later to ask other questions, hoping that guys like Dave, Ingo, Sal and others will chime in.

[wazzz]

Originally Posted by ant7

Totally understand your frustration with the schematic, I spent many hours going over it when my own ECU started doing odd things, I did learn quite a bit, although I still have the issue with my original ECU the time spent did help me diagnose an issue I had with another ECU I initially got for spares, but managed to get it up and running, I also realised there are various mistakes!
Ant.

Ant, thanks. If you remember of any errors, please let me know. I'll fix them on the schematic and will be pleased to share my own "fixed" and annotated version with you and anybody here.

[mysocal911]

Originally Posted by wazzz

Dave, thanks. But I did download and browse the TI datasheet for this ADC before I asked this (probably) stupid question.

Here is what I mean; circled in red. No +5V power supply to pin 11, only a 4.7k pull down to ground.
All other +5V lines are pull-ups, except for VREF+ (pin 12) which is connected to +5V through a 0R resistor (again a strange 0R resistor labelled B11).

So how does that ADC IC get its power supply? Is something missing on the schematic?

Yes, I know. It's another schematic error! You have a 3.2, so open your DME ECM and use an ohmmeter.

[3rd_gear_Ted]

Originally Posted by ischmitz

I would look here http://www.megamanual.com/

It’s an open source EFI project and has tons of information on how various algorithms determine fueling and spark timing. Lots of good information.

Thank you Sir, nice resource to have

[ant7]

My memory is not what it once was Gilles, but when I get chance, I will look over the schematic again, just to jog my memory, and if anything comes to mind I will of course pass it on.
Ant.

Originally Posted by wazzz

Ant, thanks. If you remember of any errors, please let me know. I'll fix them on the schematic and will be pleased to share my own "fixed" and annotated version with you and anybody here.