Coil tach input jumping/high

[Heltzen]

Hi.

I am converting a VW T3 aircooled wanagon fom dual carb to EFI (fuel only)
I am using MS1 with V2.2 board and MS1-extra software.

Getting the tricker signal by Coil (negativ)
The engine is starting and running, but the tach on TunerStudio is jumping randomly, from 1.000 to 3.000 rpm an occasionally it peaks at 13.000 rpm.
The analog tach in the car also at distributor (negativ) is floating nicely around 1.000 to 1.100 rpm, what could be wrong?

The wiring is done bye using this harness and diagram.
https://www.diyautotune.com/product/10- ... ms3-ready/

Hope anyone can help.

[Matt Cramer]

[Heltzen]

Sory, but could not find the tab to add a file

Here is the log file and the MSQ file.

VW_T3_2.0CU.msq

2016-06-13_15.37.46 total.msl

On the board:
There is a jumper between XG1 and XG2, D8 is bypassed.

This is what I've tried to fix it:
Peter Florance Tach Circuit - http://www.megamanual.com/v22manual/PFl ... ch_mod.pdf
Made it significantly worse, RPM revs floating around 90.000 RPM and just briefly coms down to 800-1000 rpm (opperside spikes)

idle.msl

This is wat i want to try now.
- Remove bypass on D8
- instead of XG1 to XG2 then XG1 to X11 and then ground pin 25 DB-37
- 0.22µf cap across the junction of D5/R10 to XG1
- Run a seperat ground wire form coil to block (coil is sitting on side of engine bay (alredy done but not testet)
- If nothing works then tap in to the hall signal at the distributor.

[Matt Cramer]

Yes, I'd first try putting D8 back into play.

[Heltzen]

Now i have have stable RPM's

Tis is what i did.
- Remove bypass on D8
- instead of XG1 to XG2 then XG1 to X11 and then ground pin 25 DB-37
- 0.22µf cap across the junction of D5/R10 to XG1

In the beginning the Log showed x1000 rpm. so cranking was betwin 25.000 and 35.000 rpm.
I uploaded a default tuning from the firmware file witch fixed the problem and now it is idling perfekt.

Next step is organizing the wiring harnes and then tune the engine.

Thanks fore input.