DIS no timing advance with bypass(SOLVED)(TUNE AND LOG)

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WillExoIX
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DIS no timing advance with bypass(SOLVED)(TUNE AND LOG)

Post by WillExoIX »

Started over here
http://www.msextra.com/forums/viewtopic ... 01&t=67033

Continuing here to document both issues separately.

Now that its running, I get no timing advance with increasing RPMs.

Have a log with the bypass disconnected, where actual timing at the balancer varies from 12* to 6*

And a log with the bypass connected, where actual timing is right about 10* +/- 2* variation but much more solid.
I have however had to change the trigger angle from 66* to about 68* because it seems to have drifted a bit after the last start.
Revving the car the timing mark on the balancer stays the same with no change with the bypass connected; so its communicating with the MS at least or setting the trigger angle would make no difference.

Lets get this fixed once and for all so we can get a viable DIS system working for the MS community and update these manuals!

1995 Camaro 3.4 running MS2X 3.4.2. with 1996 Buick Century 3100 DIS.

It's been mentioned to me that some have abandoned trying to get the GMDIS to work with the MS; I'd like to change that. Whats an aftermarket ECU if the community won't help figure it out? We should be trying to support ALL configurations in one way or the other!
Last edited by WillExoIX on Sun Aug 20, 2017 12:03 pm, edited 1 time in total.
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Boost control, Fan control, Stepper IAC, Launch/Antilag, Working on the GMDIS, and Methanol injection
WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

Copy pasting a reply from the other thread.
ChevelleFan wrote:You could try just tapping into TPS VREF for the Bypass. I do that on my HEI8 setup.

-Dave
Going to probe the bypass wire to confirm 5v, as adjusting the trigger angle works. if no go I'll give this a shot.
WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

Time to get ready for work, BUT, I went out and probed the bypass wire for voltage.

Key on engine off MS powered is .45 volts
Cranking brings it down to zero volts
Once running its up to 4.91 volts

So the bypass does carry the proper 5 volts.
WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

So Ive seen recommended trigger angles of 70* on Saturns 4cyl DIS applications.
Would that infer a different trigger angle is needed on a v6 with the same 6+1 reluctor on the crank?
WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

Anyone? Matt? James? Jean?

Don't take it as me being pushy or trying to be rude. Just trying to be driven to get this done. I want this to work properly and I want the community to be able to benefit from this information.

Even if you have gotten nowhere with it please post any info you have anyway. Sometimes all it takes is a new set of eyes on an old issue to get things solved. I am still researching and researching more while awaiting responses, through existing posts on here and any informative articles I come across.

Being HEI is almost identical to DIS as far as the MS is concerned I'm also looking into those respective posts as well.

I'm not willing to give up on this. My mindset is one that cannot be told something is not possible. Doing so just increases my resolve and makes me try harder. So rest assured I'm not giving up until this gets figured out.

Sent from my SM-G900V using Tapatalk
Last edited by WillExoIX on Sat Aug 19, 2017 8:11 am, edited 2 times in total.
WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

I have confirmed the timing shown in the logs is not the timing shown at the balancer with a timing light. There is no advance from 10° when revving.

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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by jsmcortina »

Do you have access to a scope and a car running on the stock ECU? It would be really helpful to see a fully working scope shot of REF and EST.

A factory service manual might have some information like that, but there's no substitute for an actual scope shot.

James
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WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

jsmcortina wrote:Do you have access to a scope and a car running on the stock ECU? It would be really helpful to see a fully working scope shot of REF and EST.

A factory service manual might have some information like that, but there's no substitute for an actual scope shot.

James
I can certainly ask around. But I do not personally have a scope. I'm sure I can find a running 3100 Buick though.

I assume you want the signal coming from the ECU going into the ICM yes?
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by jsmcortina »

WillExoIX wrote:I assume you want the signal coming from the ECU going into the ICM yes?
and the signal going from the ICM to the ECU at the same time so we can compare them.

James
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WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

d***, apparently my whole last post i typed up completely dissapeared :/

But the jist of it was me trying to understand the trigger angle on a 4cyl DIS compared to the 6cyl DIS. one with 2 coils and the other with 3. Would they need two different trigger angles? 4cyl was mentioned to run a 70* angle, would the 6cyl require a different angle? I know with my 123456 firing order 1 is at TDC compression while 4 is at TDC exhaust, so it COULD run 180* out. Would that cause a similar issue with no timing advance if the trigger angle is wrong?

Feel free to school me, my brain is a sponge.

James, Could I do the line in audio cable for a scope or would that not get us a clear enough signal?
WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

jsmcortina wrote:
WillExoIX wrote:I assume you want the signal coming from the ECU going into the ICM yes?
and the signal going from the ICM to the ECU at the same time so we can compare them.

James
May take a few days as I have work tonight and tomorrow night but I'll get it done.
EDIT: I do have a logic probe, but I doubt that would get the info we are after.
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by jsmcortina »

WillExoIX wrote:d***, apparently my whole last post i typed up completely dissapeared :/

But the jist of it was me trying to understand the trigger angle on a 4cyl DIS compared to the 6cyl DIS. one with 2 coils and the other with 3. Would they need two different trigger angles? 4cyl was mentioned to run a 70* angle, would the 6cyl require a different angle? I know with my 123456 firing order 1 is at TDC compression while 4 is at TDC exhaust, so it COULD run 180* out. Would that cause a similar issue with no timing advance if the trigger angle is wrong?
It depends on how GM designed the module.
James, Could I do the line in audio cable for a scope or would that not get us a clear enough signal?
That would be a start for sure. It might be enough. If you try that, scope your own car first and make sure you can see something before searching out another one.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
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WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

jsmcortina wrote:
WillExoIX wrote:d***, apparently my whole last post i typed up completely dissapeared :/

But the jist of it was me trying to understand the trigger angle on a 4cyl DIS compared to the 6cyl DIS. one with 2 coils and the other with 3. Would they need two different trigger angles? 4cyl was mentioned to run a 70* angle, would the 6cyl require a different angle? I know with my 123456 firing order 1 is at TDC compression while 4 is at TDC exhaust, so it COULD run 180* out. Would that cause a similar issue with no timing advance if the trigger angle is wrong?
It depends on how GM designed the module.
James, Could I do the line in audio cable for a scope or would that not get us a clear enough signal?
That would be a start for sure. It might be enough. If you try that, scope your own car first and make sure you can see something before searching out another one.

James
Excellent. Worth a shot. Still going to try to acquire a real scope to keep in the arsenal. Will post back soon. In the meantime I have PM'd Prof315 and encouraged him to pop in here with whatever information he may have learned from his endeavors.
WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

Quick question.
Will a single channel work or will I need a 2 channel?
Found a single channel local for $75
Two channel for $250
Tips on the preferred frequency range?
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by jsmcortina »

Two channels are required - it is required to see how the in/out signals relate to each other. A 20MHz scope should be fine, that's what I used for most of MS1/Extra development.

James
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WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

jsmcortina wrote:Two channels are required - it is required to see how the in/out signals relate to each other. A 20MHz scope should be fine, that's what I used for most of MS1/Extra development.

James
Ok. I have a lead on a used 2 channel 20mhz scope. As long as the dot appears on screen when powered up it should be workable? Awaiting response from the seller. Any easy tests for the seller to confirm the scope is workable on both channels? There are a couple scopes available just waiting to confirm they're 2 channel, which from the pictures they appear to be.
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

a 35Mhz unit should be better here no? Found a tested and working T932a Tektronix for a great price. Would rather use the older equipment as its what I have used in the past and trust it more than some of the newer stuff. From what I recall 35Mhz will be faster than 20Mhz, which should be better but i'll wait for confirmation before I pull the trigger as its been awhile since Ive used this sort of equipment.

EDIT: Nevermind, Answered my own question LOL. Pulling the trigger on the scope listed. Will take a week or so to get.
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by jsmcortina »

Sounds ok. Normally with no trigger input those analogue scopes should give two straight lines.

Turn to lowest voltage range and touch the inputs, you should see mains frequency (60Hz US, 50Hz Europe) signals picked up by your body.

James
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WillExoIX
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by WillExoIX »

jsmcortina wrote:Sounds ok. Normally with no trigger input those analogue scopes should give two straight lines.

Turn to lowest voltage range and touch the inputs, you should see mains frequency (60Hz US, 50Hz Europe) signals picked up by your body.

James
Ah yes, I forgot we used to do that when I first started in electronics classes. I found the same scope tested and working so thats the one I'll be going with.
I should have a 96 Buick Century 3100 to test on by the time I get the scope. Ill test on my car and the Buick and post up with the results once I get it.
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Re: DIS no timing advance with bypass(TUNE AND LOG)

Post by Six_Shooter »

I did have some scope shots at one point, I'll have to find them. However signals are the same for HEI7/8 as far as between the ICM and ECU are concerned.

However, I've been running this setup for a year or so, maybe longer now with the MS, though I have used the GM DIS for many years longer than that with GM ECMs.

My setup;
LX9 (3500), external crank trigger (7x), because the LX9 uses a 56x similar to some LS engines and didn't work with my GM OBD1 EFI setup, where I used the earlier 60 degree V6 ignition system (before switching to MS), that I have used on my old Franken60, my Nissan L28 and now my LX9. The only difference between the internal and external setups is that my sensor placement is adjustable, though I have it very close to where GM places it in relation to crank angle, MS2 3.4.2 (even though I have an MS3 for it, just not installed yet).

The settings as far as in Tuner Studio is concerned are identical to HEI7/8, except for the trigger angle. This must be higher than 50* to use same cylinder timing instead of next cylinder timing. Even the GM ECMs do this, and has to do with looking at one set of 3 notches while cranking and switching to a different set of 3 notches. Now one other change that I had to make was switching from standard dwell to fixed dwell of 50%. I found that standard dwell ended up with too high of a dwell period (or rather too high of a pulse width) and would drop spark at higher RPM and/or boost. I tried down to 30% or so, but found 50% to work best.

This ignition system was used bewteen 1987 and 2004 or so on FWD 60 degree V6s, including the 2.8, 3.1, 3100 and 3400, along with the 3.4L in the 1993 to 1995 F-body.

I have a document that is about 80% done that relates to the HEI and similar DIS units, but haven't had a chance to finish it up to be happy with posting it. If I can maybe I'll put some work on it later to get it up in the next couple of days.

Any problems that occur are not software settings issues, if you use standard HEI settings, except for the aforementioned changes, it will work. Any issues are likely related to hardware, be it bad CPS, poorly routed wiring, or misplaced/incorrect wiring, etc.
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