Hey everyone. I'm hoping I can summon a couple of the greybeards around here to help me out with an issue I'm having. I've spent many hours searching but have come up dry. When was the last time you've made it to page 6 of google search results? ha! The car is a '91 VVT swap that i have just finished a full rebuild with forged pistons, rods, and all new rings, bearings blah blah blah. I'm 6 miles into the break-in at the moment. The problem is I can't get the trigger wizard in TS to sync with the timing on the pulley. Rather, I have a huge trigger angle offset to get as close as I can to the commanded 10° fixed timing. The car will idle and drive seemingly fine after switching off of fixed advance. With fixed 10° timing, the pulley reads 6° and that's as close as I can get it with -30° of trigger angle offset. Clearly, something isn't right. From what I've read most vvts have around +-4° offset or even less.

What I've tried so far:
verified mechanical timing, pics below
ensured the timing marks at the pulley line up with TDC using a dowel
double checked the trigger wheel is oriented correctly. Dowel is at 12 0'clock at TDC and the missing teeth are at 9ish o'clock
all combinations of falling edge/ rising edge, vvt enabled and disabled.
verified Crank sensor is 1 credit card width from the TW teeth

Quick look at the ignition settings:




Here's the necessary info on my setup:
91 VVT swap
MKTurbo
MS3Pro (FW 1.5.1)
OEM vvt coils
36-2 trigger wheel Note: This wheel has no branding and was purchased second hand (BNIB) at MATG
OEM VVT Cam/Crank sensor
OEM balancer

Quick backstory for added context.. The car ran fine for 15-20k miles at 235hp on the unopened block until it eventually bent a rod. It was on the OEM trigger wheel during this time with no sync issues. Now its got 84mm ST 8.8 pistons, manely rods, BE oil pump and a 36-2 trigger wheel. After cranking to build oil pressure, the car fired up almost immediately after updating the tune to "Miata 36-2" spark mode in TS. I kept the trigger offset from before at about -7°. I quickly checked for leaks, dropped the car off the stands and drove around my block to start the initial ring seating (rev to 3k, coast to 1.5k and gradually upping the revs to about 5k). The car was driving fine and felt healthy. I parked it after about 2 miles/20 minutes, changed oil and filter and went back out a few days later. I put my light on and tried setting base timing but could only get it to 6° of the commanded 10°. I said close enough for now and went out for another 4 miles before a bad oil leak at the turbo popped up (big yikes). Now here I am trying to figure out this trigger angle offset issue before putting more miles on it.






Like I said earlier, I'm hoping to get some suggestions from you fine, cat-loving fellas on here. The .msq is attached.

 

Can you do more than 30 degrees of offset in tuner studio? I assume they don't limit you to 30?

The way I understand it, each tooth + gap is about 10 degrees (36 teeth+gaps if you imagine the missing 2 teeth were there), so 30 degrees would mean that the wheel you have has 3 more teeth/gaps to the 2 missing teeth than the trigger pattern is expecting.
I don't know what the megasquirt 36-2 trigger pattern is setup for, but if your trigger wheel is different than what it expects I don't think 30 degrees or so should be a concern.

Do you have a photo of the trigger wheel? I know you said the gaps were at 9 on the clock face, just curious to see if it's different from the gap on the SM/FM wheels.

 

Yes, I tried more than -30. I think the MS is limited to about +-20 degrees. Nothing changes beyond -25 or so.

I forgot to mention, since this was a no brand TW, i went ahead and ordered a SM 36-2 that arrives tomorrow just incase thats the issue. Here's a Pic of my trigger wheel.

 

Looks like a standard wheel to me.

Do you need to disable VVT when setting up base timing? Also, is this a MS3?

 

The old code (1.4) does limit to something in the 20s IIRC. Those teeth are pretty narrow, check that you are getting the correct number of triggers in the tooth logger. Also check that you don't have that time based tooth filter turned on (been a long time, it is a glitch filter with a reject time vs rpm).

 

Did you try to flip the trigger wheel upside down?

 

I don't believe so. Either way, I tried setting base timing with and without VVT enabled. Yes, it's a MS3Pro.

Ahh, yes. I read through a number of posts you participated in where a similar issue was broached. Your responses were very insightful. I'll get a log, make note of the tooth filter, and post some screenshots when I get it back together.

I'm not sure I completely follow you. The TW has one hole for the alignment dowel on the crank backplate. There's only 2 ways you could install the TW - missing teeth at 9 o'clock or 3 o'clock. I read the MS expects the tooth gap at about 90° ATDC, so the 9 o'clock orientation checks out.

Either way, the SM 36-2 wheel comes in the mail today. I'll try to find time after work to put it all together and report back with a log. I got this no-brand TW for pennies so I didn't mind replacing it with the SM one to rule out problems with the TW itself. I appreciate the help so far guys.

 

I have nothing to add other than my aftermarket sensor (DIY Autotune) didn't like the tiny teeth on my trackspeed trigger wheel so I made one with magnets, so airgap isn't an issue. This would come up in your logs as missed teeth though.

 

Alright, I got the new SM trigger wheel in today and got everything back together. You were right in noticing the teeth are a bit on the small side when comparing it to the SM wheel.


Outside of the teeth being thicker, both wheels line up the same. So, my expectations were low. I got everything back together and, after forgetting to tighten the vvt oil supply line and spewing a quart of oil on my garage floor, it started up and idled just fine. Sadly, the issue still persists.

I did noticed something strange that further confirms something funky is at play here. Take a look at these two photos. Both photos were taken with falling edge and fixed 10° commanded from MS.



This first photo is taken with -30° trigger offset. This is as close as I can get it to match with the 10° fixed advance.



Now for the funky part. This photo is taken with only a 0.5° added to the -30° for a -29.5° trigger offset. Very strange. whether I add or subtract 0.5° the timing jumps like, what, 10°? You can hear the car reacting anytime it's taken off of -30° by any amount. I'm not meaning like a gradual change in revs or sound as it gets further away from -30°. I'm talking the car reacts as if some switch or table was activated. Presumably from the timing jumping ~10°, but why would it act this way?

Tomorrow I'm planning to start fresh with a fresh basemap and see what happens. I really don't know what else to try at this point. I've attached a log from earlier. On another note, should I be concerned with starting and idling it with it having so low actual miles on the rebuild? I'm at 6 miles and already changed oil and filter after the first two miles. I'm really wondering if it's safe to run it with the -30° offset (4 degrees retarded from the 10 commanded) for now while I get another 20 miles to finish seating the rings. Thoughts?

 

I'd try with an OEM Mazda crank sensor and verify the 0,5mm space between sensor and trigger wheel with a feeler gauge.

 

EDIT - Went back up and saw you had checked the marks at TDC - I just realized you're using the stock crank pulley. Any chance that slipped? I'm not super familiar with the symptoms but I've heard of it happening and I think it can cause the timing marks to be off or move around.

Just to share my experience with a similar issue. When I rebuilt my engine I swapped in a 36-2 wheel assuming that it was supported by the Speeduino ECU I was running, however I found out later that it wasn't. I cranked it multiple times for a good while trying to get the thing to fire up. That was with 80 degrees instead of ~210, so 130 degrees off. I remember getting some backfiring and condensation out of the tailpipe. It was super stressful and I thought I was going to run it too dry and break something. 10K miles later and it's fine. All this to say if the cars idling happily I doubt you've damaged anything yet, but I also wouldn't drive it much more until you feel comfortable that you've sorted the issue out.

@curly any ideas on why you wouldn't be able to get the timing marks to line up after going to a 36-2 wheel?

 

No, I've been following this thread all along, but can't think of anything y'all haven't mentioned and OP has tried. I would check mechanical timing, swap wheels, verify it's not backwards, and make sure it's not slipped. All of which he's done, except check for slipped pulley, dunno if he's checked that yet.

If the pulleys good, I'd be suspecting a firmware or hardware issue within the MS, so I'd want to check another ECU or check the ECU on another car. Checking with a 4 tooth might give some answers, or at least hints if it's firmware (the 36-2 vs. NB trigger settings), or hardware, whatever hardware deciphers the crank input within the MS.

 

Alright everyone, call off the dogs. I found the issue!

I went to load up Braineak's Trubokittiy basemap for an NB2 and pasted over the relevant configurations from my currnet tune and noticed a setting in the ignition options window that was different than mine.



Huh, strange. I questioned if the car would even start with this since my tune is set to "Normal." I flipped this to inverted on my current tune and the car fired right up. I was able to dial in the base timing with a much less offset of -9°. That's still a little high, but now 10° on the MS now lines up with 10° at the pulley. Maybe someone with more insight can learn me what this setting means. Either way, I think the issue is resolved. Thank you everyone for tuning in and offering the suggestions. I don't have a cat to share as an offering, so hopefully a Corgi will suffice.




Thanks again guys!

 

Good work getting it figured out. I have no input on the solution or why it worked (never tuned a Megasquirt), but that Corgi is pretty damn adorable!

 

Probably ran in the other setup since they run wasted spark?

Also when you say that MS is looking for the missing teeth 90* ATDC, that must be at the cam sensor right? Bc looking at those tooth wheels the gap is def going to hit the sensor at BDC, but at the cam that would be 90*…?

Excuse the ignorance if it is blatant; I’m much more versed in Haltech-speak