Trigger Angle Offset & Trigger Wheels

[MrMuddle]

Hi All, I have a potentially really stupid question, so please feel free to mock me if it is that stupid!!!

Ok here goes, I just wanted to check, I've got my e39 528i running off Megasquirt 2 now and I'm running a parallel install with the stock ecu, so stock ecu is still controlling all the relays and EWS, currently also the ICV and still does the tach out.

The only wires I've actually cut so the ecu can't do anything with them is the injectors and coils, otherwise everything else is spliced so the MS and stock ecu are sharing the same signal wires and grounds and all the sensors are using their original grounds.

So my question is, to sync my timing from MS to the crank I used the Tooth #1 Angle(deg BTDC) adjustment, so my ignition timing was slightly out so I adjusted it from 330.0 to 334.0 so the timing marks lined up and MS could command the correct timing. So if the stock ecu is still sharing all the same wires from the crank sensor etc, could it also adjust this angle and effectively change my ignition timing?

Please excuse my massive waste of your time if that really is a stupid question, but I've never done anything with coils and crank wheels before, so I wasn't really sure how it all worked and I wanted to check before I start tuning the car!

Cheers
Rob

.......goes and hides under the table awaiting a reply......

[Butters Stoch]

So, "Mega Piggy Squirt" or "Piggy mega Squirted" !

[MrMuddle]

lol yeah, I'll probably switch the ICV over to MS as well at some point, main reason I left the stock ecu in place so to make it more PnP while I set it up and to run the EWS and stock dash gubbinz!

So was my question utterly stupid or will the stock ecu still retain any control over that tooth angle adjustment? I don't want the stock ecu to effect the ignition timing at all as I'm boosted now.

[someguy2800]

The ecu cannot change the crank sensor signal. The trigger angle that I and others have found to be correct is 324.5, unless a euro motor is different, which may be for all I know

[MrMuddle]

Thanks for the info, I tried lower and higher values on the tooth #1 angle and it only seemed to line up on 334.0. Just to check, I am lining it up to the raised line on the block just to the right(clockwise) of the crank sensor and then to the mark on the trigger wheel where it says 0 | T?

Sorry for the stupid questions, so how does the tooth angle relate to the ignition advance, I know it's about x number of degrees before TDC, but the bit I don't really understand is the tooth angle. So I get if I change the angle from say 334 to 324 or 344 it would retard/advance the timing(whichever way around it is), but how is the ecu controlling that change and have I removed that ability from the stock ecu just by not allowing it to control the coils?

Sorry...I'm not as stupid as I sound.....honest!!! lol
Cheers

[someguy2800]

The O l T mark on the balancer is top dead center for cylinder 1. If you are testing with a timing light and the mark on the front cover lines up with the O l T mark, then the coil is firing at top dead center. It should be firing before top dead center.

The trigger offset just tells the ECU where top dead center is based on how many degrees it is after the missing teeth. Basically the ECU is reading the teeth go past the sensor and it waits until it sees the first missing tooth go by. Each tooth is 6 degrees apart so it counts the teeth going by to figure out what angle the crankshaft is. In our case top dead center is 324.5 degrees after the missing tooth. So now that the ECU knows where top dead center is, it can calculate when it should be firing the spark plug. For example if you have 15 degrees of timing advance in your timing table, then it needs to fire the plug 2.5 teeth before top dead center.

So the actual ignition timing is controlled only by the ECU. If you get the trigger offset setting wrong by 10 degrees, then the timing will also be wrong by 10 degrees. The correct way to verify the timing on megasquirt is to set the timing to a fixed number. You can do this in the wheel decoder menu. Under the "fixed advanced" drop down select Fixed Advance, then set the fixed advance number to 12 degrees. Start the car and let it idle. Take a reading with your timing light. The #1 coil should be firing exactly 2 teeth before the O l T mark on the balancer. Adjust the trigger offset number until its perfect. Once you have it set turn the fixed timing off. Check it again while it is running on the timing table. It should match the ignition advance shown on the dashboard of tuner studio. If you did in fact have the advance set to 0 degrees before, it should idle much better now.

[dburt86]

make sure the timing is locked at 0, like SG2800 said.

[MrMuddle]

Thanks very much guys, that makes much more sense now.

I did do the fixed timing but I wasn't sure which mark I should be lining it up too, so my timing is definitely out then as I had it set to 10degrees and I lined it up with the | mark! Doh!. Ok I'll do it again with fixed timing, adjust the timing to 12degrees, set the trigger angle to 324.5 and then make sure I can count 2 teeth before the 0 | T mark. So I assume once I go back to my timing table, if I've done it right and my timing at idle is 10degrees, it should be firing just a smidge less than two teeth before the 0 | T mark.

Thanks again

[someguy2800]

Yep you got it. It will most likely be happiest idling at about 15-20 degrees. Once you have the trigger settings correct you can play with the timing table to find the smoothest idle.

[dburt86]

If your tune is rough and it has a hard time idling at 0 degrees, you can get an adjustable light, put the light on 10 or 15 or 20, fix the timing to the same value, and the 0 mark will line up again.

[NOTORIOUS VR]

You will certainly have to add IAC duty and get fueling right to have it idle ok @ 0 DEG advance

[MrMuddle]

Thanks guys, it idles ok and didn't have any problems running it while setting the timing. I've got it idling pretty nice at about 14.6 AFR with what I thought was 10degrees advance, but I guess is actually 0degrees?! I was amazed how well it ran and started tbh, was much better that other MS setups I've done, but this is my first MS Bimmer. I
I'll get the timing set properly though so I know I'm commanding the correct timing. Hopefully the car should feel even better afterwards.

[MrMuddle]

Just coming back to this after a while and hope someone can answer my query. I was just going to load up a new firmware but was checking my timing first. I just noticed that if I changed the trigger angle on my current firmware the timing didn't actually change, it only changed if I adjusted the fixed timing value! So I'm wondering if my timing has been out all this time as I noticed the trigger angle setting was back at 334* as well whereas I'm sure I changed it to 324.5 as above!

So correct me if I'm wrong, but if I had it set to 334 and then even if I set it to 0* for fixed advance and lined it up with the 0 | T mark, technically it should be 10* retarded based on the values alone?

When I was just playing with the trigger angle, I could set the fixed timing to 12* and the car would run and still appear to be at 12* even if I changed the trigger angle from 312.5* all the way to 338*!!! If I set it to something like 360* the car wouldn't start, so it seems like the trigger angle is having some effect, but maybe its not working properly when I'm trying to set the timing with fixed timing!!

I'm going to load up the latest firmware and try it again to make sure it changes, but I'm just trying to work out if I'll need to retard/advance my whole spark table by 10* if it had been using a trigger angle of 334*!
The main reason I was double-checking the timing/angle again is I'm still getting random misfires and now anything over 9.1psi my car misfires! That's with all grounds checked, iridium 7 plugs, new coils etc etc, so something isn't right somewhere!!

Any thoughts please would be great.
Cheers

[cj.surr]

That's weird, changing the trigger angle should definitely be changing the timing respectively. Dumb question, but you were cycling the key after changing that, right?

[MrMuddle]

I tried both but I didn't think you needed to turn the key on/off, as you should be able to adjust the angle with the car running as long as its an angle it can run at. I know you need to change between fixed\use table with the car not running.

I could measure and hear the advance changing when I changed the fixed timing...it was just the angle that didn't seem to want to play ball!

[cj.surr]

A lot of core settings like trigger angle require an ecu reboot to take change, but it seems like that's not the issue if you tried that. Trigger angle should definitely affect timing. Try adjusting it in 10 deg increments while making sure the ecu reboots every time.

[someguy2800]

If you use the trigger angle wizard (I think thats what its called) you can adjust it in realtime to see the changes by just clicking the arrow up and down.

[MrMuddle]

I think it was definitely a bug in that older firmware, as I loaded up the 3.4.2 firmware last night and changing the trigger angle did change the advance, so could see it was working differently! So I set my trigger angle to 324.5 and then fixed timing to 0* and it lined up perfectly with the 0 | T mark. I then marked two teeth from TDC and checked the timing on them and it lined up perfectly also. Car now runs much smoother in general, just need to finish dialling my VE table back in and then I can try more boost.

On the trigger wizard, I think you only get that for certain trigger types, as if you choose Toothed Wheel it greys out the Trigger Wizard, so you have to set the angle etc just in the ignition options screen.

Thanks for the help guys.