My 1985 CRX is finally starting and running well enough to worry about setting the timing. I'm using a stock but locked distributor for the signal to MS, which is controlling the timing.
I would just like to make sure that I understand the relationship between the trigger wizard, trigger offset, and advance as set in the tables.
The Trigger Wizard, in this instance, is used to equilabrate the VR signals coming to the MS from the distributor to the actual position of the number 1 cylinder.
It took 22 degrees in the trigger wizard to line up the timing light to the TDC mark on the crank pulley. Essentially, this means that the VR signal the MS receives is 22 degrees out of phase with TDC. It doesn't mean that the base timing is 22 degrees advanced. The trigger offset is not a component of the spark advance table, just a synchronizing device.
Stock base timing for the CRX is 16 degrees.
If I leave the crank pulley mark at TDC and don't set it to base timing mark, the cells in the advance table will be net of the missing base advance. So, if the relevent table cell was 16, the actual physical advance would be zero. If the cell was 14, total timing would occur 2 degrees ATDC.
I then reset the timing so the light flashes on the base timing mark. In this case, if I have the table cell at 16 degrees, the spark will occur 16 degrees BTDC, which is the base advance. If I have it at 14, MS will retard the signal by 2 degrees of rotation.
Right?
Big Picture: Trigger Offset and Advance
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
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Matt Cramer
- Super Squirter
- Posts: 2951
- Joined: Sat Jul 03, 2004 11:35 am
Re: Big Picture: Trigger Offset and Advance
It sounds like you get it - though you may be overthinking things a bit. The table should be the real advance. The Trigger Offset is the angle before TDC that the MS gets a pulse from the VR sensor. When this number is dialed in correctly, the advance in the table should match the real advance. The Trigger Wizard is just a handy way of setting trigger offset.
Re: Big Picture: Trigger Offset and Advance
Thanks, Matt! Since you have such a good way of explaining things, I've ordered your book. I expect to know and understand all once I've read it;>
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turbo-brooks
- MegaSquirt Newbie
- Posts: 20
- Joined: Tue Jan 11, 2011 7:08 pm
Re: Big Picture: Trigger Offset and Advance
since this thread directly pertains to what I was going to post..
I had a heck of a time getting my project to start, it wasn't until I took a wild guess at the timing bieng the culprit as to why it wouldn't start - but I had the offset set anywhere from 20-60*, and all it would do was vrrrrrrrm - pfft.. lol.
I just out of the blue knocked the reference angle back to -15*and it kicked off and ran for 30 seconds.. at that point I started logging and got it to start, idle and run good by VE, WUE, ASE etc..
MY question is, since it's "running good" at -15*, it will only line up at 0* on the balancer (with a timing light set at 0), or close to it- if you try to get the base of 40* that I"m commanding, it dies instantly. I'm assuming that since the reference is negative, MS can't or doesn't have the time to make the timing adjustment BECAUSE of the VR phasing?.. as in, it needs to be moved to correct the relation of the sensor to the pickup?
I had a heck of a time getting my project to start, it wasn't until I took a wild guess at the timing bieng the culprit as to why it wouldn't start - but I had the offset set anywhere from 20-60*, and all it would do was vrrrrrrrm - pfft.. lol.
I just out of the blue knocked the reference angle back to -15*and it kicked off and ran for 30 seconds.. at that point I started logging and got it to start, idle and run good by VE, WUE, ASE etc..
MY question is, since it's "running good" at -15*, it will only line up at 0* on the balancer (with a timing light set at 0), or close to it- if you try to get the base of 40* that I"m commanding, it dies instantly. I'm assuming that since the reference is negative, MS can't or doesn't have the time to make the timing adjustment BECAUSE of the VR phasing?.. as in, it needs to be moved to correct the relation of the sensor to the pickup?