VB921 resets

Keithg · Post by **Keithg** » Sat Apr 01, 2006 5:58 pm

Well, I have 2 VB921s mounted on a V2.2 board. Running MSnS-E 029L. Been driving one coil. It works fine. I just mounted the coil pack (EDIS4) and I get resets when running both spark outputs. I read this link:
http://www.msefi.com/viewtopic.php?p=105554#105554
Heribert mentions a resistor and cap for this fix.
Right now, the VB921s are mounted to the top of the case. They are grounded to one of the ground pins. The MSnS docs specifically mention pin 15. Should I ground these differently? As it is, I cannot drive it due to resets.

KeithG

Keithg · Post by **Keithg** » Sat Apr 01, 2006 11:04 pm

Answering my own post. again.
Tons of resets, then I thought... maybe it needs resistor plugs. I replaced the BCP7ES with BCPR7ES-11 and all the resets went away. Oh, and I fouled 2 sets of the BCP7ES in the process.

Now I get a noisier RPM signal, but I can drive it. I'll have to see if shielding helps it out any. Odd, but with a single coil (MSD blaster) and only one VB921 driving, there were no problems with resets or with these noise spikes. The VB921s are grounded to the head.

Resets all the time:
http://www.wideopenwest.com/~kgrider/sa ... 012353.xls

Resets gone (only change is resistor plugs) but rpm signal noise:
http://www.wideopenwest.com/~kgrider/sa ... 020015.xls

36-1 wheel decoder, GT1 hall sensor, 029l, Wasted spark with Ford EDIS coilpack.

Suggestions welcomed.

KeithG

Keithg · Post by **Keithg** » Sun Apr 02, 2006 6:11 pm

Shielding attempted, but no improvement. Erratic rpm signal.

Input is a hall sensor fed into the opto. Before this I had a rock steady rpm signal. No comments? Suggestions? Or is it that there is less traffic here than on the MSnS-E forum? Isn't this the appropriate forum for this, or should it be in msns-e?

I'll need to strap a scope on it and see what is going on. ANy hints as to what to look for?

another log:
http://www.wideopenwest.com/~kgrider/sa ... 021452.xls

Keithg · Post by **Keithg** » Mon Apr 03, 2006 5:09 am

re-read the other reset posts and changed the 'base' resistor of 330 ohm to 690 ohm and it is MUCH better. Still noise on the RPM trace, but it does not buck under boost like before. I'll try 1k tonight.

http://www.wideopenwest.com/~kgrider/sa ... 030741.xls
http://www.wideopenwest.com/~kgrider/sa ... 030747.xls

KeithG

Post by **jsmcortina** » Mon Apr 03, 2006 5:14 am

Mine seems ok with 330R but that was a massive improvement over a direct connection which had lots of nasty resets when motorway cruising.

James

purple people eater · Post by **purple people eater** » Tue Apr 04, 2006 3:52 am

i had a monstor reset problem with my version 2.2 board and a vb921, my fix was adding 100 ohm resistors in the wire from the leg of r25 that triggers the vb921, i ended up adding a total of 5x 100 ohm resistors and the problem was solved, they were later replaced by a single 570ohm resistor, i hope this helps

purple people eater · Post by **purple people eater** » Tue Apr 04, 2006 3:54 am

oops i just realised you linked to my original post

cosmo1stgen · Post by **cosmo1stgen** » Fri Apr 07, 2006 4:52 pm

I also had this problem when installing MS on a buddys VW with wasted spark. Tried the resistors on the vb921s from 330 ohm to 6000 ohm very little improvement ended up leaving them at 330 ohm. All the grounds were also run to the same place. Turns out it was the spark plug wires that were causing the problem. The wires he was using measured 700 ohm and were causing tons of RFI causing the resets and eratic high RPM readings. Replaced the wires with resistor core wires (measured 6000 ohms) and the problem went away completely. Havent seen one reset in hours of driving and tuning.

Keithg · Post by **Keithg** » Fri Apr 07, 2006 6:03 pm

put a 0.1uf cap from the hall lead to ground. No improvement. It starts fine and drives reasonably, but under boost I can get a buck. When I look at the trace, it is an RPM spike. every time. it is very well shielded to a different ground point than the power ground. The VBs have a separate ground going to the 'star'. the grounds are a 'star' with all components going to a single head bolt. Since it is drivable, and I have not had time to break out the scope, i'll wait until I get COP going and see if the rpm spikes go away with the CD COP system.

KeithG