I originally made a post asking for help with an intermittent sputtering issue I had been having with my car. You can view that thread here: https://brickboard.com/RWD/volvo/1692480/940/960/980/V90/S90/945_b230f_regina_intermittent_sputtering_acceleration_940_sputter_roughrunning.html

It had always been an idea in the back of my mind to throw a custom ecu in this car and do some other things to get it making some more power. During the process, I realized, information on this stuff can be few and far between, so I decided to make this thread.

This sputtering issue was the last straw for me and I decided to go ahead with a custom ecu.

I have no experience with anything like this, and while I consider myself to be technically and mechanically inclined, this is my first car, and at that, my first project car. I'm 18 as well, so I'm running on a very slim budget; most of the money I make has been going into this Volvo.

The ECU I went with was a Speeduino. Specifically the Ocelot from WTMTroinics. I chose this board for a few key reasons. It is on the more affordable side, it was designed with 4 channels in mind, which is perfect for my 4 cylinder Volvo, and is open source. I am a big fan of anything open source. This board has been great so far, although I haven't really gotten to properly use it since my car hasn't started.

Every guide I could find on installing custom ECU's recommended that I make a wiring diagram for everything before I start wiring, but I decided to just wing it and do one thing at a time until everything that needed to be wired was. This worked out okay for me and since I'm so paranoid about things actually being connected properly, I just double triple checked everything making sure polarities were correct and continuity was correct. What I can say, is watch out for shared grounds. I wired my fuel pump up and when I turned the car to run, my passenger side window rolled down. It was a comedic way to find out about shared grounds and an easy fix, but I figure I'd mention it so you can learn from my mistakes. Wiring kind of sucks, nothing ever stays where you want it to when you have to go grab more connectors or heat-shrink, but with persistence, I did it.

It's easy to say this considering my car hasn't started since I've put a custom ecu in it, but as far as I can tell everything is wired correctly and all of the data looks right.

That is, except for my crankshaft positioning. That has been the main struggle for me on this project. The trigger pattern on my car's flywheel is called Renix. You can read about it here https://wiki.speeduino.com/en/decoders/Renix but what you need to know is that even if you get a signal, there is only enough information to use distributor routed ignition. While I could do that, in my opinion, that defeats half the purpose of a custom ecu. Without being able to adjust ignition advance, it's hard to make more power.

What now?
I'm working on returning a camshaft position sensor that didn't end up working, as it has the same issue as before, not enough information for ignition. That was quite expensive and I don't have much money, especially now with Xmas around the corner. Until I return it, I don't have the money to explore other options. What I will likely do (and what should hopefully, finally work) is attach a trigger wheel from somewhere like DiyAutoTune or this one from BlingFactory https://www.blingfactory.fi/epages/blingfactory.sf/en_GB/?ObjectPath=/Shops/20101220-11092-13436-1/Products/BF300050to my harmonic balancer and rig up a mount for a hall sensor to read the trigger wheel.

I didn't go too far in depth on any specifics, but if there are questions, I'd be glad to try and answer any. I also got some other goodies for my car, like a new cam from IPD and I plan on doing the accumulator mod to my AW71 transmission. (hopefully someday I can manual swap it)
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Nathan Micklatcher