Switching LED 19 to spark B causes guage misreading

ion332 · Post by **ion332** » Thu Aug 17, 2006 8:49 am

Ok, here it is:

I have switched to 3 VB921s, and everything is fine until I switch the output of LED 19 to Spark B.

Once I do that, the guage readings all go up for some reason. I am using 29q2.

Any ideas about what might cause this?

Post by **jsmcortina** » Thu Aug 17, 2006 8:51 am

Which gauges? Oil pressure gauge?

What setup were you running before? What is your full setup now?

James

ion332 · Post by **ion332** » Thu Aug 17, 2006 9:00 am

Engine map, coolant temp, and MAT.

They all read +43F disconnected. Normally they read -40F.

The MAP guage reads about double (189 instead of 97 for ambient)

It works fine initially, but, when I power down the MS, and it comes back up, thats when the corruption occurs.

Now, by placing LED 19 back to Warmup, it goes back to normal.

ion332 · Post by **ion332** » Thu Aug 17, 2006 9:05 am

The only things that I changed since last time:

1) I put in 3 VB921s off of the LED outputs

2) I connected the Fuel Pump output to a relay to power the coilpack

3) I put in a secondary wheel trigger opto and connected it to U1 Pin 11

4) I also momentarily reverse-voltaged the MS during testing on my lab supply. Protection diodes should have shunted that and saved it, but, I don't know. It communicates and turns on just fine, everything else seems fine. Once again, if I program LED 19 back to its normal output then power it down, it goes back to normal so this leads me to believe the hardware is ok.

5) When installed, everything looks fine, I get a tach signal, the whole deal as long as I don't enable spark B.

Post by **jsmcortina** » Thu Aug 17, 2006 9:33 am

Are you getting a configuration error? Fuel pump led flashes on and off. For 3 VB921 you need three spark outputs not two.

James

shaodome · Post by **shaodome** » Thu Aug 17, 2006 9:35 am

like what James said....

You will also need to configure the spark triggers in the wheel decoder

ion332 · Post by **ion332** » Thu Aug 17, 2006 9:48 am

jsm: I do not get a configuration error. I *do* get one if I try to dump the msq. That explains a few things.

shaodome: I haven't configured the spark triggers at all. If I was using time based, I didn't think you had to? That is prlly my problem. Duh. lol.. Its been a hellish last couple of weeks between finishing up an MS install on a BMW and going to a zillion different interviews all around the country.

Post by **jsmcortina** » Thu Aug 17, 2006 9:53 am

If you want three spark outputs you must define triggers A, B, C. How else will the Megasquirt know when to fire the coils?

James

ion332 · Post by **ion332** » Thu Aug 17, 2006 10:03 am

OK, did that now..

But, the fuel pump is still flashing.

And, does this look right:

wheel decoder base teeth : 3
2nd trigger enable : 2nd trigger
2nd trigger active edge: falling like IRQ
2nd trigger and missing teeth : no missing

trig pos A: .25
Trig return A: 0
Trig pos B: 1.25
Trig return B: 0
Trig pos C: 2.25
Trig return C: 0

Dual dizzy mode : normal
Wheel decoder routing : 025 style

When I do the excel sheet, I get the above. When I reset the MS, it shows A: 0 B:1 C: 2
I don't think that the excel sheet info is right, I thought you needed whole numbers?

ion332 · Post by **ion332** » Thu Aug 17, 2006 10:36 am

OK, that fixed it.

I set it this way

Trig A: 1
Trig B: 2
Trig C: 3

and the error went away. So, thats good news. All is good.

Now I gotta finish this install before I collapse from exhaustion.