M42 piggyback fuel controller wiring

[axisofjustice]

Also on rev... trying to find someone who wants to give a once over.

So to be able to tune fuel my piggyback needs:

Power - Ground - AFM In - AFM Out - RPM In

The E30 M42 Motronic pins that correspond to this seem to be:

Power = Pin 54 (Red/Wt) [Tap]
Ground = Pin 55 (Brn/Or) [Tap]
AFM In/Out = Pin 41 (Grey/Yel) [Cut]
RPM Signal = Pin 74 (Blk) [Tap]

Would someone please check my work? Does it look like this will do?
I know it looks like I am asking for a handhold and I'm not denying it.
This is my first foray into wiring in this car. Next is LC-1 install.

[wazzu70]

I will review the wiring diagrams and verify these are the correct pins.

The wiring can be tricky, and there is not a ton of info out there for the M42 engine as you know!

Also, its good you actually made an attempt to locate the correct pins without just asking for the answer I learned a lot wiring up my standalone and struggling to understand rather than just ask for the answer. You learn a lot more that way!!!

[axisofjustice]

Yes, I've tried to do my own work. I really hate how most people want free legwork because of online forums. I just do not want to go out there and do something I mistaken and fry my ecu or run lean and kill my engine. So I just want someone who has been in my place to check my work. Thanks!

[wazzu70]

I looked at the wiring diagrams and your pins seem correct. Only question I have is whether the RPM signal for the tach works like you have it listed, or if the unit wants a signal from the VR sensor (67, yellow).

Doing it the way you have it makes less a chance for interference though as VR sensors can be fussy.

Pin 28 is brown/orange. Pin 55 ground is just brown and its also the ground for sensor shielding. Pin 28 is the ground for the VR sensors, so I would stay away from that, and use 55 as listed....just be aware its not striped.

[axisofjustice]

Thanks Nick! I am glad to see I was so close to being right, I really tried to get it right. Thais for among some time out to check it over for me.

[wazzu70]

No problem. Its always nice to know you aren't way off in space for these things.

The wiring diagrams are not always clear!

Keep us up to date on your project!

[axisofjustice]

Wow, my iPhone really chopped up that thank you I wrote. I should be going out to install the wide band and computer later this weekend. I may put a build thread up soon, I have a lot to do to the car this month.

[axisofjustice]

Got the fuel tuner installed, I did some other engine work too. Still need to install the wideband and put the cam over and supercharger back on.

[axisofjustice]

For any who actually read this...

It runs again! Roughly.

The Bosch Volvo 32# injectors are in, so it the fuel tuner, and now the old o2 is out and the wideband is wired and will be finished tomorrow. The supercharger is in, the new cam gears are on, and new gaskets all around, as well as some paintwork.

Now, I hope it is just a few tweaks from idling nicely, I am hoping the injectors are to blame for the bad lope at idle and not the cam timing, as it appears correct.

[wazzu70]

Glad to hear its working for you!