Cold Sync Errors

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gsellstr
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Cold Sync Errors

Post by gsellstr »

Been digging for a similar issue but haven't found much. I'm running an MS2 V3 box running 3.3.2 code, car is a 1990 Volvo 740 turbo.

I'm running the stock VR style crank sensor (stock wiring including grounded shielded wire from the sensor to the ECU) and the native 60-2 pattern on the flexplate, also have tried a Kia sensor with a much stronger magnet, still have the same issues.

When I start the car cold (under 70* ambient temp, 12.9v at the battery), I will get anywhere from 1 to 10 sync errors (error 2), only until the engine starts getting warm, typically the errors die out within the first 30 seconds. Once the engine has barely started warming up they are gone, car runs flawlessly, clear to the limiter, WOT at 20psi of boost, even 105* ambient temps without a single sync error. The engine never fully dies, but it isn't pleasant waiting to see if it will die or not this time around. Warm starts are fine as well, even if the engine has only been running for a minute or two. Trying to grab a log tonight I got 1 chance. After 30 seconds it started just fine with no errors. Ambient temp was about 68*, sun had just gone down so MAT was a little higher.

I've tried adjusting the VR pots, didn't make a difference in the temp issues. Currently they are backed out fully CCW.

I've seen quite a few threads, but not a single one that actually posted back up with what the resolution actually was.

I tried grabbing a comp log from it but forgot to hit the save to log file so it didn't save anything. Watching it, nothing seemed to show up, but given the speed, it's hard to catch something without the log. Attached is what I was able to save, not sure if it will help or not.
Matt Cramer
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Re: Cold Sync Errors

Post by Matt Cramer »

I'm having trouble with the composite log; can you grab a new one and use the tooth logger instead?

I have seen cases where cold sync errors were resolved by a tighter sensor gap.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

I'll try and grab another log tonight.

I did actually try tightening the gap up and the issue got worse. Opened the gap up a little from stock and had no real change. Only way to close the gap is by filing the sensor down since the bracket is fixed on the block, but I have some very thin washers I was able to use to space it up about .020".

That was actually one of my first attempts to fix it. :)
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

Tried grabbing a tooth log file tonight, figuring at 70* outside and having sat for 6 hours, that it would act up. Didn't even burp once.

Here's the datalog and tooth log files anyway...
Matt Cramer
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Re: Cold Sync Errors

Post by Matt Cramer »

I'm sorry, but that tooth logger is a textbook case of what the signal should look like. There is an upside, though - it'll serve as a great point of comparison once you're able to get a tooth log of what went wrong.

I wonder if soaking the sensor in ice water would get it to lose sync? Or using cold spray on it?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

Hmm, an interesting thought as that would alleviate all issues with wiring in one shot, along with the VR pots. Might see if I can find some cold spray (pretty sure the local radio schmuck has had it in the past).

Thought that trigger looked spot-on. That's kinda why I'm having issues figuring this one out.

If the car didn't have to get smogged here in Cali I'd go with a DSM CAS like my other car has (running MS1V3) and be done with the VR thing.

We're getting nothing but hot days for the next week so chances are I won't be able to grab a log, but I'll give it a shot saturday morning since I'll be up early before it breaks 70* (I hope).
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

So, haven't had a chance to grab some spray to cool the sensor, but that may not be the issue.

I tried 3 times to datalog the sync errors and every time it worked flawlessly, so there was nothing to log. The 4 times I drove the car without the laptop connected it acted up all 4 times, anywhere from 60* to 90* ambient temps.

Next time I drive it I will try unplugging the DB9 from the ECU and see if it still acts up, in case there's some form of transient noise being induced via the cable. Seems odd I know, but why else would having the laptop connected fix the issue? I did try starting it with the cable laid out as it would be when connected to the laptop (normally it's coiled up inside the glovebox), that made no difference at all.

If that fixes it I may just spring for the bluetooth adapter setup...
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

Okay, so now I'm frustrated. Cable unplugged from the ECU I still get sync loss for the first 30 seconds of startup. Connect it, same thing. Plug laptop in, no issues at all. Unplug laptop, restart, sync issues, within 30 seconds of no issues with the laptop plugged in.

One thing I am curious on. The person who built this setup for me to fit in the stock ECU case removed the end plates from both ends for size fitment. Any chance that may be an issue with the outer shield on the DB9 not case grounded?

Otherwise I'm at a loss why it's fine with the laptop but not without, and why it's still only the first 30 seconds or less that the car is running.
Matt Cramer
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Re: Cold Sync Errors

Post by Matt Cramer »

This does sound like it might be a grounding issue - where exactly is the ECU grounded? Any corrosion on the ground lug?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

ECU is physically attached where the stock ECU is located, inside the car, pass. side footwell. Electrical grounds are to the intake manifold, same place the wideband is grounded, with a dedicated #12 from that bolt over to the battery as well, in addition to the normal block-battery, block-chassis and #0 alternator-block grounds, all of which are clean and tight.

Is the outer metal shell on the DB9 case-grounded normally inside the standard MS ECU case? If so, that may need to get a plate built and re-grounded. Otherwise it almost seems like there needs to be a termination plug in the end of the cable when the laptop isn't plugged in, which seems really odd. I've had absolutely no issues leaving the DB9 plugged into the ECU but not a laptop for the last 9 years on the MS1 car in the garage.

Hmm....
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

FINALLY! I tried grounding the DB9, no change. Caught the car acting up, connected the laptop, and managed to catch a short log while it was acting up.

Current map, datalog, and comp log attached.
Matt Cramer
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Re: Cold Sync Errors

Post by Matt Cramer »

Looks like you got one extra noise pulse near the missing tooth. Maybe try an inline resistor.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

Any idea on size? I may have some 1k's at home perhaps.

Just inline on pin 24, or from 24 to ground?

Any thoughts on possibly a filter cap on the ground side as well? Had to do that on the coil drivers on my MS1 box to deal with some tach issues.
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

So, haven't put in a resistor yet, still searching for a ballpark size to try. Drove the car tonight and it fought me for a good 60-90 seconds, even giving it throttle didn't help. This was definitely the worst it has been, but it was also just over 100* ambient temps out.

Haven't found a decent starting point on the resistor route yet, may try a 1k, 5k, and 10k, see if any of those help, unless somebody has a recommendation.
gsellstr
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Posts: 12
Joined: Tue Jul 22, 2014 10:19 pm

Re: Cold Sync Errors

Post by gsellstr »

So, seems as though the noise filters did absolutely nothing, so I turned them back off. Seems like it was if anything a little worse with them on. Last night I pulled the ECU apart to find the builder (linuxman51) had already installed a 10k resistor inline on the VR signal lead. Talking to another friend and long-time MS'er, I put a 1k resistor across the VR sensor from the signal to ground lead. Still had some issues but fewer sync losses. Tried a second one in parallel (making it a 500-0hm resistor) and so far it hasn't had a single loss since, both cold and hot ambient temps. Still winds out to the limiter clean as well. Time will tell as the week progresses, but that may have done the trick.
gsellstr
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Re: Cold Sync Errors

Post by gsellstr »

Issue seems to be resolved completely. It definitely would have acted up on the drive to work today, but instead it performed flawlessly (aside from a minor tune related issue).

Seems to be a solid fix.
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