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Old 11-11-2021, 01:48 PM   #11
Board Member
Join Date: Dec 2019
Location: Sacramento, CA

Thanks for all the advice. I am so close - actually, getting this CAS set up is the last step before firing my b20! But assuming I am reading the logs , I must have done something incorrectly or otherwise screwed some setting up. Any advice would be super appreciated. Hoping for any friendly Volvo advice before I jump into the MS forums...

I have the CAS wired as in bobxyz's excellent post, and am using the Yoshifab disc. I have done the mods in 5.2.3 for Tach and for Cam. The Crank/Tach mod was easy. For the cam, I used the IAC1A plug on the DB37 connector (it was jumpered elsewhere to JS0, I removed and taped the jumper wire off). I also had to remove a jumper on JS10 (was jumpered to the middle pin of Q16) since the instructions were clear that nothing else should be on JS10.

The result is... not what I expected. Neither the tach signal nor cam signal (are they separate?) appear solid - they jump around a ton as if the pull-ups were not there (the pull-ups are there). The composite log when I removed the CAS and spun it by hand was similar to when it was on the engine. This is what it looks like by hand:

I went over all of my (admittedly, novice) soldering connections but they all appear to have continuity where they should, and the resistance is matching the pull-up resistor circuits:

The only customization on the back should the wasted spark jumpers:

And my settings in Tuner Studio:

What have I screwed up, I wonder? Any advice welcome!
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