MS3 and LT1 Camaro

Testing and development of Megasquirt 3

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Re: MS3 and LT1 Camaro

Postby jsmcortina » Sun Aug 21, 2011 11:32 am

sportage4x4 wrote:The LT1 ecu does not use the 360 slots for anything critical. It is used to calculate engine speed at and just above idle speed so that the idle speed stabilization routine can react quicker than simply waiting for the long slots. It does not compare the edges of the 360 slots with those of the 8 slot track. It does, however, use both edges of the 8 slot windows and can sync sequentially within 180 crank degrees.

That does tally up with the fact that the "broken" MSD optis will work with it, but also seems rather perverse. What's the source of your information? How authoritative is it? The LT1/Opti information that I've read makes big of the high-resolution of the CAS that can reduce spark scatter which _suggested_ that the hi-res track was being used.

As found earlier in this topic my code does seem to work ok with OEM Optis, but not with the MSD ones. It seems a shame to through away the hi-res information although from what I've seen all(?) other aftermarket ECUs ignore the hi-res slot.

James
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Re: MS3 and LT1 Camaro

Postby sportage4x4 » Sun Aug 21, 2011 12:33 pm

i gathered that from the factory service manual and some deduction. Like you noticed, the OEM ecu will run with the 360 slot track in any orientation with regards to crank position.

It does help to reduce spark scatter. it allows the ecu to more accurately calculate instantaneous engine speed, and therefore, more accurately calculate dwell.
1990 Mazda Miata: GM Gen3 V8 swap, 4.8L, custom cam, 2x GT2860R turbos, MS3 + MS3X.
2003 Kia Rio wagon: Mazda B6T/G25MR swap, Miata CAS, IHI RHF5 @ 2bar, LSx truck coils, P&H board, boost control.
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Re: MS3 and LT1 Camaro

Postby jsmcortina » Sun Aug 21, 2011 12:45 pm

Any chance you could share any of that detail? Here or offline ?

James
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Re: MS3 and LT1 Camaro

Postby sportage4x4 » Sun Aug 21, 2011 1:03 pm

i'm off to the shop shortly, and will post some scans of pertinent information when i get there.
1990 Mazda Miata: GM Gen3 V8 swap, 4.8L, custom cam, 2x GT2860R turbos, MS3 + MS3X.
2003 Kia Rio wagon: Mazda B6T/G25MR swap, Miata CAS, IHI RHF5 @ 2bar, LSx truck coils, P&H board, boost control.
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Re: MS3 and LT1 Camaro

Postby sportage4x4 » Sun Aug 21, 2011 2:56 pm

Sorry, I was confused. After re-reading my notes it turns out the OEM ecu does use the 360 slots all the way up the rev range. It appears as though the ecu counts the number of pulses that fall between the leading and trailing edge of the larger slots to determine which cylinder is firing. No where is it mentioned however, that the 360 slots have any special timing relevance to the crankshaft. It is mentioned several times that the leading edge of the 8 slot track are in time with TDC for each cylinder. Only mention of counting the edges on the 360 track between leading and trailing edges of the 8 slot track is made. It is mentioned that both the leading and trailing edge of the 360 slot are used, and that they are used to reduce spark scatter and more accurately control coil dwell. no mention is made of their angular relationship to the crankshaft, or even to the 8 slot track. these engines will run with only the 8 slot track functioning, but with "reduced quality" as the service manual puts it.

I've almost finished mounting the MS3/X setup inside the OE ecu case (as well as a microsquirt for 4L60E trans control), so i can also help with testing perhaps by next weekend.
1990 Mazda Miata: GM Gen3 V8 swap, 4.8L, custom cam, 2x GT2860R turbos, MS3 + MS3X.
2003 Kia Rio wagon: Mazda B6T/G25MR swap, Miata CAS, IHI RHF5 @ 2bar, LSx truck coils, P&H board, boost control.
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Re: MS3 and LT1 Camaro

Postby jsmcortina » Sun Aug 21, 2011 3:22 pm

sportage4x4 wrote:these engines will run with only the 8 slot track functioning, but with "reduced quality" as the service manual puts it..

Very interesting - I wonder if the MSD Optis are actually running in reduced quality mode?

The only way I can think to test would be to look at the spark stability under engine accel/decel events from low rpms and compare between the OEM and MSD Optis.

James
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Re: MS3 and LT1 Camaro

Postby sportage4x4 » Sun Aug 21, 2011 4:47 pm

I doubt they are running in reduced quality mode, as that mode sets a DTC for the high resolution reference signal.

Is there anyway we can count the number of edges of the 360 track as seen by the ecu between the leading and trailing edges of the 8 slot track? I bet the MSD and OEM opti both have the same number of edges between the leading and trailing edge of any given 'tooth' on the 8 slot track. Where the OEM may be rising the MSD may be falling (on the 360 slot track) but the OEM ecu doesnt appear to care.
1990 Mazda Miata: GM Gen3 V8 swap, 4.8L, custom cam, 2x GT2860R turbos, MS3 + MS3X.
2003 Kia Rio wagon: Mazda B6T/G25MR swap, Miata CAS, IHI RHF5 @ 2bar, LSx truck coils, P&H board, boost control.
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Re: MS3 and LT1 Camaro

Postby jsmcortina » Mon Aug 22, 2011 2:20 am

I tried counting both edges, but with the MSD opti, the edge was so close that it was sometimes before and sometimes after, so the count was inconsistent and caused a loss of sync.

James
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Re: MS3 and LT1 Camaro

Postby pimp4lyphe » Mon Aug 22, 2011 3:01 pm

James,

Where can I find the best working version of the code that you sent to Dookie454? I'm at the wiring stage of setting up MS3/3X on a SR20DET motor with 360/4 CAS.

Thanks.
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Re: MS3 and LT1 Camaro

Postby jsmcortina » Wed Aug 24, 2011 1:39 pm

The code is still a work in progress and it will be at least next week before I have another version.

James
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Re: MS3 and LT1 Camaro

Postby Dookie454 » Thu Aug 25, 2011 1:43 pm

Comparing datalogs between the stock PCM created with Datamaster ~10 points/sec and both stock+MSD opti's, and datalogs created with Tunerstudio on the MS3 10-15points/sec, in the rapid accel area's I see the stock PCM RPM log is very jagged and uneven rate of increase. With Tunerstudio + MS3 + MSD opti I see the RPM log very smooth. Unfortunately I am only able to test the MS3 with the MSD opti in real world, in low res mode so I don't know if this is creating "smoothing" therefore not sure if the difference is due to the OEM PCM reading all 360 slots being more accurate, or if it's due to allot of error in the stock PCM.

If you would like to see a picture of the two RPM graphs I could post one later.
Current:
1997 Chevy Z71 Vortec 350 4x4, MS3X, 4.66 or 4.95 khz good so far, Knock using BOSCH - 0261231036 (stock 1 wire resonant style did not detect knock and had input drift when elec. fan came on).
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Re: MS3 and LT1 Camaro

Postby Dookie454 » Fri Aug 26, 2011 8:49 pm

sportage4x4 wrote:i'm off to the shop shortly, and will post some scans of pertinent information when i get there.


I have a 94 service manual (attached), should be the same?
The service manual says it provides "angle based timing information to the PCM for individual cylinder spark timing. The ignition module (the optics in the opti) is capable of providing both 4X and 360X timing pulses each crankshaft revolution. Using these timing pulses, the PCM processes ignition spark timing and sends an IC signal to the ignition coil module to activate the secondary ignition system." It continues to say "The PCM will compare the 4X and 360X signals to each other to determine the location of the number one cylinder and top dead center". DTC 16 will be set if the 4x signal is missing, DTC 36 will be set if 360X is missing. "The vehicle will not run if the 4X signal is not avail at the PCM for processing."

It sounds to me like the low res signal is ok for sequential injector pulse, but it needs the high res to calculate very accurate spark timing, so there may be a split system in the stock PCM, one that runs the injectors sequentially off the low res signal, and the ignition system that relies on the high res+low res signals to calculate TDC for #1 cyl, and if the high res signal is not avail, it defaults to low res.

I've learned the Big Stuff and Fast systems only wire up the low res wire, therefore if they are getting 8 seperate sequential injector pulses, they are doing it from the low res signal. Since they do not use the high res signal I can only assume they are also running the OEM ECU's version of "reduced performance and poor fuel economy" since spark in those systems is based off of the low res 4X signal.

This makes sense since there are 8 slots total in the low res, every other is a different length, so the PCM knows what cylinder to fire, but needs the high res to know when exactly to fire it for ignition accuracy.
Current:
1997 Chevy Z71 Vortec 350 4x4, MS3X, 4.66 or 4.95 khz good so far, Knock using BOSCH - 0261231036 (stock 1 wire resonant style did not detect knock and had input drift when elec. fan came on).
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Re: MS3 and LT1 Camaro

Postby LT1buggy » Fri Sep 02, 2011 4:52 pm

I don't mean to butt in but I am planning on running a Mega III on my LT-1. I want to use the opti for trigger but was planning on making a new shutter wheel. If you have made it work with the 360/8 shutter wheel that would be awesome. Can I get some info on your progress??? Thanks for any help I need to get this buggy on the road.
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Re: MS3 and LT1 Camaro

Postby Dookie454 » Wed Jan 04, 2012 7:09 pm

James, nice work! I ran the code you sent earlier for the problematic MSD Opti, v 1.223 2011-12-23 01:56:18

It synced fast and runs!! And pretty good too! In full sequential at least I believe I have it setup in that mode. The only settings I changed were:
Spark Mode: Changed to Optispark (trigger angle previously set to 45, and skip pulses = 3)
Cam input = MS3X Cam In,
Fuel settings: Sequential ON: Fully Sequential

I didn't drive it but had it running for 20mins and had only 2 sync loss, first at ~9mins (1398s in the log), and the other at about 14mins, (1738s in the log). I heard the first one hiccup lean, and didn't notice the second one but I was just idling along. It didnt do it any of the times I blipped the throttle, I didnt rev very high.. 2000rpm.

All of the other settings (including noise filtering) are carryover from what you recommended a while back to get batch fire running smoothly, which it did.

Dan_383_25_METH_OPTIWORKING.msq


Dan_383_25_METH_OPTIWORKING_MSL.zip
Current:
1997 Chevy Z71 Vortec 350 4x4, MS3X, 4.66 or 4.95 khz good so far, Knock using BOSCH - 0261231036 (stock 1 wire resonant style did not detect knock and had input drift when elec. fan came on).
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Re: MS3 and LT1 Camaro

Postby jsmcortina » Wed Jan 04, 2012 8:07 pm

Sounds like things are moving in the right direction, good.

Did you double check the timing? With 45 degrees of offset in there you are likely to be 20degrees advanced !?

Double check that and perhaps try turning off all of the noise fitlering.

James
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Re: MS3 and LT1 Camaro

Postby Dookie454 » Wed Jan 04, 2012 9:41 pm

I don't have ignition connected yet, the MS3 is running fuel only. Stock PCM controlling spark. Should I change 45 to 25? At some point I had a problem with MAP Sample Settings, so I changed MAP sample to 40 and Trigger Angle/Offset to 45 and it worked. What do you think they should be set at?

The LT1 doesn't have timing marks that I've seen so it will be hard to check.
Current:
1997 Chevy Z71 Vortec 350 4x4, MS3X, 4.66 or 4.95 khz good so far, Knock using BOSCH - 0261231036 (stock 1 wire resonant style did not detect knock and had input drift when elec. fan came on).
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Re: MS3 and LT1 Camaro

Postby Dookie454 » Thu Jan 05, 2012 6:41 pm

jsmcortina wrote:Sounds like things are moving in the right direction, good.

Did you double check the timing? With 45 degrees of offset in there you are likely to be 20degrees advanced !?

Double check that and perhaps try turning off all of the noise fitlering.

James


Today I ran it with settings you suggested:
1) Noise Filtering: OFF
2) Tach Period Rejection: Off
I also reduced the 45 degrees to 25 since you mentioned it could possibly be 20 degrees advanced (I didnt see any info about Optispark in the manual for this setting)

I got one sync loss after about 4 mins of runtime, and ran it for another 13mins with no problem. Reason 65

This sync loss dropped to 0rpm and back up to normal, nothing else looked affected.

I'll try driving it soon, see what happens.
Current:
1997 Chevy Z71 Vortec 350 4x4, MS3X, 4.66 or 4.95 khz good so far, Knock using BOSCH - 0261231036 (stock 1 wire resonant style did not detect knock and had input drift when elec. fan came on).
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Re: MS3 and LT1 Camaro

Postby jsmcortina » Thu Jan 05, 2012 6:48 pm

Dookie454 wrote:I also reduced the 45 degrees to 25 since you mentioned it could possibly be 20 degrees advanced (I didnt see any info about Optispark in the manual for this setting)

I'm thinking this should be set to zero. The code is _intended_ to have the required offset built in. That won't be confirmed until someone runs a coil from it and strobes the output.

James
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Re: MS3 and LT1 Camaro

Postby Dookie454 » Thu Jan 05, 2012 7:06 pm

jsmcortina wrote:
Dookie454 wrote:I also reduced the 45 degrees to 25 since you mentioned it could possibly be 20 degrees advanced (I didnt see any info about Optispark in the manual for this setting)

I'm thinking this should be set to zero. The code is _intended_ to have the required offset built in. That won't be confirmed until someone runs a coil from it and strobes the output.

James



I actually just picked up 8 LS Truck coils with harness and brackets today since I was reading through the manual and it mentioned they were logic level and the MS3X was by default logic level ready... so... I might be ready to swap to MS Spark very shortly.

Would connecting the MS3 to the default OPTI coil work just as good for this test or would running 8 coils separate be best?

I think the only thing slowing me down is figuring out how to get TDC markings on the main pulley. At first I wanted to keep the stock knock detection working.. but I also just installed a meth kit.. so that should take care of knock.. at least at the current advance.. plus I will still have "after the fact" knock reporting using the scanmaster.

Maybe.. just maybe I can set the stock PCM (currently controlling spark) to a set value of say 10 degrees... then fire it up, watch the reported timing on a computer, then make my own marks on the balancer+block with a timing light? I think this would effectively tell me where 10 degrees is.. a point of reference. I could even make 10 and 15 degree marks.
Current:
1997 Chevy Z71 Vortec 350 4x4, MS3X, 4.66 or 4.95 khz good so far, Knock using BOSCH - 0261231036 (stock 1 wire resonant style did not detect knock and had input drift when elec. fan came on).
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Re: MS3 and LT1 Camaro

Postby Matt Cramer » Fri Jan 06, 2012 6:14 am

I think the stock LT1 ignition has some sort of external module that takes a 5 volt signal, so that should be easy to run with the MS3.

When we find ourselves dealing with an engine that doesn't have timing marks (like the new Hemi, which CAN'T even have timing marks from the factory because the damper is not keyed to the crank!), we usually use a piston stop to find TDC, and draw timing marks on it with White-Out, a paint pen, or whatever else we can get to stick to the damper. Forcing the stock PCM to run 10 degrees should work in theory - as long as the timing was correctly set at the factory.
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