Megasquirt 20b Na
Thread Starter
Joined: Aug 2001
Posts: 15,725
Likes: 91
From: Near Seattle
20b Na
It's been a year. I want to get back into this project.
MS I CPU, v2.2 board and MSnS-Extra022i6. Custom VE and spark tables transliterated into assembly from something renns helped me with last year.
The 20B is an early one #756 so it'll stay NA. It also needs a rebuild because it has worn apex seals and smokes. It still has enough life left in it to fire up and run reasonably well, at least while in warm up mode, so it'll be a little while before I tear it down.
When last it ran, it had those tell tale oscillations in warmup mode and then would totally stall when the fast idle solenoid would close. I couldn't keep it running with my foot. It also didn't want to restart until it had a chance to cool back down to below the threshold.
I disabled the thermowax. I feel the throttle stop needs to be set a little further open than it currently is. I set it blind.
This is my first EFI engine and my first aftermarket ECU.
Edit: I've added an MP3 audio clip of the oscillations. Just unzip and listen.
MS I CPU, v2.2 board and MSnS-Extra022i6. Custom VE and spark tables transliterated into assembly from something renns helped me with last year.
The 20B is an early one #756 so it'll stay NA. It also needs a rebuild because it has worn apex seals and smokes. It still has enough life left in it to fire up and run reasonably well, at least while in warm up mode, so it'll be a little while before I tear it down.
When last it ran, it had those tell tale oscillations in warmup mode and then would totally stall when the fast idle solenoid would close. I couldn't keep it running with my foot. It also didn't want to restart until it had a chance to cool back down to below the threshold.
I disabled the thermowax. I feel the throttle stop needs to be set a little further open than it currently is. I set it blind.
This is my first EFI engine and my first aftermarket ECU.
Edit: I've added an MP3 audio clip of the oscillations. Just unzip and listen.
Last edited by Jeff20B; Aug 6, 2006 at 03:49 PM.
Thread Starter
Joined: Aug 2001
Posts: 15,725
Likes: 91
From: Near Seattle
Late Leading with 1st gen J-109 ignitors and Diamond coils. I plan to run three FC trailing coils and leading ignitors eventually.
The spark seemed slightly on the weak side, but I adjusted the dwell until it mirrored stock settings.
I'd still like to upgrade to FC parts eventually. I just need a couple more trailing coils and one more leading ignitor base.
The spark seemed slightly on the weak side, but I adjusted the dwell until it mirrored stock settings.
Code:
Stock VR MS ignition
---------------------------------------------------------------------
| 500RPM dwell: 11%, amps: 0.32
| 600RPM dwell: 14%, amps: 0.40
| 700RPM dwell: 16%, amps: 0.46
| 800RPM dwell: 18%, amps: 0.52
| 900RPM dwell: 20%, amps: 0.56
900RPM dwell: 22%, amps: 3.3 (1.1) | 1000RPM dwell: 21%, amps: 0.63
2000RPM dwell: 44%, amps: 6.0 (2.0) | 2000RPM dwell: 43%, amps: 1.25
3000RPM dwell: 56%, amps: 7.4 (2.46) | 3000RPM dwell: 63%, amps: 2.28
4000RPM dwell: 60%, amps: 8.1 (2.7) | 4000RPM dwell: 59%, amps: 1.95
| 5000RPM dwell: 52%, amps: 1.50
| 6000RPM dwell: 44%, amps: 1.08
| 7000RPM dwell: 39%, amps: 0.80
| 8000RPM dwell: 32%, amps: 0.45
| 9000RPM dwell: 29%, amps: 0.34
| MAX dwell: 65.5%, at 3100RPM, amps: 2.38
Numbers in parenthesis are estimated amperage per coil where 3.3 ÷ 3 = 1.1
Senior Member
Joined: Nov 2005
Posts: 310
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From: Phoenix, AZ
I just had a look at your post on the ms boards and damn....
We have a large group of guys who run mega squirt here in alberta that i have been talking to and they are all amazed at your work.
I thought they were troopers but you are just plane weird.
a good weird
Nice work btw.
We have a large group of guys who run mega squirt here in alberta that i have been talking to and they are all amazed at your work.
I thought they were troopers but you are just plane weird.
a good weird
Nice work btw.
Thread Starter
Joined: Aug 2001
Posts: 15,725
Likes: 91
From: Near Seattle
Thankyou.
I wonder what would happen if I were to switch over to what few FC parts I have. Sitting here, I've got two leading ignitors and one trailing ignitor. Not enough coils though. If the compensation and dwell is similar between leading and trailing, maybe I can solve my weak spark issue by using FC ignitors and keeping the 1st gen Diamond coils for now until I can come up with one more leading ignitor and two more trailing coils.
I wonder what would happen if I were to switch over to what few FC parts I have. Sitting here, I've got two leading ignitors and one trailing ignitor. Not enough coils though. If the compensation and dwell is similar between leading and trailing, maybe I can solve my weak spark issue by using FC ignitors and keeping the 1st gen Diamond coils for now until I can come up with one more leading ignitor and two more trailing coils.
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Thread Starter
Joined: Aug 2001
Posts: 15,725
Likes: 91
From: Near Seattle
I forgot to mention both ignitors were tested with the same coil (Diamond) and a BR8EQ-14 spark plug.
Something strange just happened. When I went to test an FC leading and trailing ignitor, they kept cutting out. They'd only seem to work at 500 to 700 RPM. It would start to cut out at around 900-1k RPM and it continued at higher RPM so I aborted the test. The ignitors were pulling 6 to 7 amps and the dwell was topping out the guage.
Just to make sure all was ok, I hooked up the J-109 again and all was well with it. Infact, it peformed slightly better than in the dwell list above; it pulled slightly more amps and the dwell reading was (favorably) slightly higher.
By the way, I tried several different dwell settings while trying to get the FC ignitors to work, but no luck. Even Muy's recommended 2.6 and 0.5 didn't do the trick. I may have overlooked something this time, but from what I can remember during my bench testing last year, is that the FC stuff performed about the same as J-109s at low RPM, but then really came into their own as RPMs went up.
Well whatever. My car is currently set up to use J-109s with Diamond coils, so that's what I'll use. I suspected I had a weak spark which was causing some running problems, but now I think it was something else.
Something strange just happened. When I went to test an FC leading and trailing ignitor, they kept cutting out. They'd only seem to work at 500 to 700 RPM. It would start to cut out at around 900-1k RPM and it continued at higher RPM so I aborted the test. The ignitors were pulling 6 to 7 amps and the dwell was topping out the guage.
Just to make sure all was ok, I hooked up the J-109 again and all was well with it. Infact, it peformed slightly better than in the dwell list above; it pulled slightly more amps and the dwell reading was (favorably) slightly higher.
By the way, I tried several different dwell settings while trying to get the FC ignitors to work, but no luck. Even Muy's recommended 2.6 and 0.5 didn't do the trick. I may have overlooked something this time, but from what I can remember during my bench testing last year, is that the FC stuff performed about the same as J-109s at low RPM, but then really came into their own as RPMs went up.
Well whatever. My car is currently set up to use J-109s with Diamond coils, so that's what I'll use. I suspected I had a weak spark which was causing some running problems, but now I think it was something else.
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