OK can anyone running a vauxhall c20XE with wasted spark please list up theyre wheel decoder setting. i have found 4 differing sets of figure on megasquirt forums so far and given that tooth out will be 6 degrees of difference then thats quite a bit.
Mines are 10/18/ 40/48 and trigger return.

But I have also found 11/19 41/49 and 12/20 42/50


I was told to set it up using a timing gun but the one i borrwed does not like the wasted spark and James from Msefi recomends a std gun where there is no facility to dial in advance. I'll need to mark up the pulley as it only has TDC marks at the moment. I just have a niggle that its not quite right ( and if the second set of figure are right then I'm at least 12 degrees out to start with.) I have a sort of clacl clack clack noise coming from the air intake pipe at times. mostly under very light loads. Think of the clip clop noise you make with your tongue on the roof of your mouth. It's very tedious as I have takn the inlet of cold air from the cockpit now and it's become noticeable and annoying.

Like you I found more than one set of timings that allegedly worked on an XE.
In the end I worked it out from scratch and confirmed it with a cheapo timing light.

10/18/40/48 and trigger return.

So you're spot on.

Paul.

Just to confuse everyone, I ran 11/20/41/50. Are the wheels in exactly the same position on dizzy and coilpack engines?

For MS1 the values depend on the Angle you set in "Spark Settings", as your telling the ECU that at xx tooth the angle = yy So you need to know what xx and yy are rather than just xx

You can easily work it out with a torch and a straw.
Remove the crank sensor, turn the engine over until you get cy #1 to tdc (straw in spark plug hole)
Now get a torch (remove the straw first ) and look down the crank sensor hole and turn the engine over in the opposite direction to which it normally rotates.
Count the amount of teeth that pass until you get to the gap in the teeth.
With a minus 2 setup (Vauxhall/bosch) then you must count the first missing tooth you come to, the next missing tooth will be zero as this is the first reference the ECU sees.

Now you know the tooth number that passes the sensor at TDC.

Download this program and enter the data and youll get the answers to xx and yy
http://www.extraefi.co.uk/software/wheeldecoder.xls


For MS2, you can do the same as above but you dont need to use the file as you only need to know what the angle is for tooth #1

Phil

[Edited on 24/5/11 by daxtojeiro]

OK so a night fiddling and here's how it went.

I borowed an old style bog std timing strobe. I then did a cad drawing for the pulley dia of 142 and divided it into 10 degree divisions did a trim to between the 10 degree lines and found the arc length of 12.4mm. Marked a bit of masking ape at 4 off 12.4mm spacings ( to give a total of 10/20/30/40/ deg BTDC) and wrapped it round the pulley taking care not to stretch it and then transfered the marks in marker pen to the pulley itself.

Timed it as it was and it was way out. Then I removed a plug (no1) and set at tdc ( i used a dial indicator and a wooden dowel in the spark plug hole for accuracy) then it transpired that my tdc pulley mark and pointer were slightly out of line so i squared up the pointer.
Then I removed the crank sensor and counted back the teeth. A wee bit confusing because being anal it started at a half tooth (trough) and at countback it was 21 teeth ( counting the space for tooth1) or if you like 21 1/2 teeth.
So set it at 11/19 41/49 and timed it again with the light. It was still a wee bit out and at 12/20 42/50 it looked better ( this is all under cranking mind not running.
So I ran it up and watching tuner studio advance and reading off of the crank pulley. It seems more accurate at 11/19 41/49 so I have set it at that.

How far out would my spark settings/table have been across the board by being 1 to 1.5 teeth out?? 6 to 9 degrees I reckon.

Set the fixed angle to 10deg

Use a strobe and adjust the" Trigger Angle" until you get 10deg advance on the strobe.

Undo the fixed angle

Job done

Phil