MS3Pro - 20 Degree Timing Jump *SOLVED*

pjkinsella · Post by **pjkinsella** » Wed Apr 26, 2017 5:07 am

Hey guys, I'll do my best to describe my situation here. I've done a lot of searching and keep coming up with different issues. I can post my tune later (at work currently) if you think it's relevant after reading this, but the logs don't show anything relevant (unless I'm missing something).

My Setup:
I just installed an MS3Pro on my 1998 Viper GTS (V10 oddfire). The engine has a lot of modifications, but is still N/A. I'm running the factory ignition coils (5 coils, wasted spark), and I made an ignition module to fire them using (5) BIP373's from DIYAutotune.

Checking Timing:
I made up a timing point, found TDC, etc. and after realizing my old timing light was dead, I bought a new Innova dumb inductive timing light. I set timing to fixed at 20 degrees (I'm running a pretty big cam). At idle, timing jumps around a bit, but that doesn't bother me since it has a pretty lopey idle. Give it a very slight amount of throttle and it smooths out properly and it's rock-solid at 20 degrees. For reference, I had to adjust my start angle to -4 deg.

The Symptom:
The timing stays rock-solid at 20 degrees as I slowly rev the engine, until, at some point that doesn't seem to be consistent, the timing advances about 20 degrees (literally just jumps from 20 deg. to 40 deg.) and sits there, rock-solid, normally until I let off the throttle and it goes back to idle. Once at idle (normally), it'll snap back to 20 deg. and stay there until I rev it up again.

Things I've Checked:
- TunerStudio shows no loss of sync.
- The ignition timing gauge stays at 20 degrees, as it should with fixed timing.
- The engine doesn't noticeably sound any different when it jumps.

Help!
Is there anything else I can check or look for as an indicator? Is there maybe a setting in TunerStudio I might be missing?
I hope to check it with someone else's timing light, but I don't have high hopes that it's just my timing light causing it.

The engine seems to be running pretty well, and I've done a decent amount of driving around the neighborhood, but haven't pushed it too hard.

Thanks to anyone with any ideas ahead of time, and if I need to get my tune file up, let me know and I can do that later.

elutionsdesign · Post by **elutionsdesign** » Thu Apr 27, 2017 5:59 am

Need the tune file.

pjkinsella · Post by **pjkinsella** » Sat Apr 29, 2017 5:48 am

elutionsdesign wrote:Need the tune file.

Tune file added to OP. Sorry for the delay, need to change my notification settings for this forum.

Matt Cramer · Post by **Matt Cramer** » Mon May 01, 2017 7:27 am

Can you make a composite log as well? This will help assess if something has gone wrong with the RPM input signals.

pjkinsella · Post by **pjkinsella** » Tue May 02, 2017 12:58 pm

Matt Cramer wrote:Can you make a composite log as well? This will help assess if something has gone wrong with the RPM input signals.

I'm gonna have to do a search to figure out how to do that, but yes, I will as soon as I have a chance to get back on it.

pjkinsella · Post by **pjkinsella** » Tue May 09, 2017 9:09 am

Okay, so I finally had a chance to mess with it last night for a bit. Attached is a screenshot of the composite logger. It stayed consistent through the RPM range.

I checked it with a timing light with the timing advance set to use the timing table an the behavior is different. At low idle, the timing is jittery. When it revs to maybe about 900-1000 rpm, it stabilizes and advances as expected up to about 2000 rpm, where it gets jittery again. Once you near 3000 rpm, it stabilizes again. It's quite odd.

In the process, I determined that I have a dead coil (not the no.1 coil), but that shouldn't matter for this. I figured I should mention just in case I'm wrong (very possible).

red-racing · Post by **red-racing** » Tue May 09, 2017 11:50 am

how is it possible to strobe the ignition when its oddfire AND wasted spark?
the lamp will pickup the spark from the sharing sylinder, but the timing is different

pjkinsella · Post by **pjkinsella** » Tue May 09, 2017 12:52 pm

red-racing wrote:how is it possible to strobe the ignition when its oddfire AND wasted spark?
the lamp will pickup the spark from the sharing sylinder, but the timing is different

The short answer is yes, BUT you might be onto something. I'll explain my theory and hopefully someone smarter than me will jump in to tell me if I'm crazy.

I would assume that a "dumb" timing light would strobe with every spark. Now, I bought a "dumb" Innova inductive timing light, but after looking at its "features" it's not quite so dumb. They claim it has "skip circuitry" to allow for faster rpms. This tells me that it starts electronically skipping spark events to flash on, depending on rpms.

Normally this would be perfectly acceptable, but in the case of odd-fire wasted spark, how would it "know" which spark event to skip? It may not be a coincidence that the timing looks jittery at 1000 rpm intervals if it's skipping the wrong spark event when "optimizes" its flash at certain rpm intervals. In fact, I have witnessed the speed of the flashing dramatically change. I need to check and see if it changes with every 1000 rpms...

Someone who's smarter than I, please speak up!

whittlebeast · Post by **whittlebeast** » Sat May 13, 2017 7:52 pm

I know next to nothing regarding your trigger wheel but.......

When I was sorting out my install, I was getting the same sort of 20 degree timing jump. The issue was traced down to using a VR for the crank sensor and a Hall on the cam sensor. As soon as I went to optical pickup on the cam and Hall on the Crank, poof, all of my timing issues went away.

See http://www.msextra.com/forums/viewtopic ... da#p496814

Andy

Matt Cramer · Post by **Matt Cramer** » Mon May 15, 2017 7:09 am

After looking at things a bit more closely - for an odd number of cylinders, odd fire, and wasted spark - you will actually get two timing signals separated by the difference between the odd fire angle and the angle between cylinders on an even fire engine. And on a Viper V10 - that works out to 20 degrees.

pjkinsella · Post by **pjkinsella** » Mon May 15, 2017 8:05 am

Matt Cramer wrote:After looking at things a bit more closely - for an odd number of cylinders, odd fire, and wasted spark - you will actually get two timing signals separated by the difference between the odd fire angle and the angle between cylinders on an even fire engine. And on a Viper V10 - that works out to 20 degrees.

Excellent. That's the conclusion I was REALLY hoping for!

Now I need to figure out my ignition output issue and how the heck to keep from frying SSR's for my alternator control and hopefully I'll be set.

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MS3Pro - 20 Degree Timing Jump SOLVED

MS3Pro - 20 Degree Timing Jump SOLVED

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