Lost sync all at once on good system

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srb94
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Re: Lost sync all at once on good system

Post by srb94 »

Thinking I may need to go back to basics on vr setup. Not that I think its wrong, but by elimination I haven't verified polarities on sensor wiring, settings, etc. it just ran. Could that be the marginal issue I am now fighting. Worked and then some minor drift got me not working anymore. Will have to relearn what is needed as I last studied what megaswuirt wants about 5 years ago. Was considering noise filtering but should address this first maybe.
Steve B.
srb94
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Re: Lost sync all at once on good system

Post by srb94 »

Bill,
You asked about the VR gap. I wasn't able to find anything to useful in the factory manual but it is 36-1. I put some modeling clay on the end of the sensor and shoved it in place. one of the teeth indented the clay near the center. I was then able to cut away some of it and measure nominally 0.045 in. gap.
I also did a bunch of reading and verified (i think) the polarity is correct(with the approaching voltage positive and the negative edge indicates a crossing point). What confuses me is that the input capture is on the rising edge which i would think should be incorrect. Changing it means the engine doesn't run. on another thread James M. said that you should verify the correct edge polarity by the tooth logger, which looks good.
So,where am i? I have checked and rechecked everything but am coming up blank. I looked into the sync log a bit more, opened it in excel. i find something at 2058.492 that I can't understand or know what it means. note that the columns don't line up below.

PriLevel SecLevel Trigger Sync ToothTime Time
Flag Flag Flag Flag ms ms

1 0 0 1 0.412 2058.4922
1 0 0 1 0 2058.4922 <--- what happened here?????
1 0 0 1 0.397 2058.8892
1 0 0 1 0.405 2059.2942
1 0 0 1 0.407 2059.7012
1 0 0 1 0.407 2060.1082
1 0 0 1 0.408 2060.516
1 0 0 1 0.409 2060.925
1 0 0 1 0.408 2061.333
1 0 0 0 0.821 2062.154

I also realized that i had explained the rebuild but not posted my current MSQ after that rebuild so here it is.
Steve B.
slow_hemi6
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Re: Lost sync all at once on good system

Post by slow_hemi6 »

What happened there is it seems to have registered a 0ms tooth. Noise among the typical 0.4 second tooth gaps at a guess.
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
billr
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Re: Lost sync all at once on good system

Post by billr »

I assume the sensor air-gap is not exposed, you can't measure it with a feeler-gauge or similar. I also kind of assume the air-gap is "built in" and can't be reasonably adjusted. That .045" is more than I would like, but we have to keep in mind this was running fine previously. Remind me, have you tried a new CKP sensor, same type as in there now?
srb94
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Re: Lost sync all at once on good system

Post by srb94 »

billr wrote:I assume the sensor air-gap is not exposed, you can't measure it with a feeler-gauge or similar. I also kind of assume the air-gap is "built in" and can't be reasonably adjusted. That .045" is more than I would like, but we have to keep in mind this was running fine previously. Remind me, have you tried a new CKP sensor, same type as in there now?
Yes, the air gap is a machined bore into the front casting. Difficult to change or measure directly. I did try a new sensor with no change, in fact that was the first thing I tried thinking it was an intermittent failure. I also tried measuring the sensor in hot oil to simulate the engine conditions. Everything tested good.
It may be possible to move the sensor in by filing off the flange area, but the signal at idle is currently at 10 V p-p with the missing tooth area higher. Seems like that should be good but......
Steve B.
srb94
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Re: Lost sync all at once on good system

Post by srb94 »

slow_hemi6 wrote:What happened there is it seems to have registered a 0ms tooth. Noise among the typical 0.4 second tooth gaps at a guess.
Many thanks. This is the first (and so far only?) concrete data that corresponds to the problem. What kinds of things can cause this to happen? I agree with your comment on noise but from where? Interesting coincidence that it occurs exactly at the tooth interrupt and shows up on the log as an extra missing tooth. I had already tried ferrite beads on every input line (and many outputs) I could find. Again, there is about a 10 V p-p signal at idle that appears clean, which seems like a nice safe place. Is there something else I should investigate.
Steve B.
slow_hemi6
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Re: Lost sync all at once on good system

Post by slow_hemi6 »

I set up my noise filter to ignore ridiculous signals years ago and moved on with things. I have the filter ON and Tach period rejection ON. The Time I have set a 0 because I prefer to use the Percentage (of last trigger) which I have set at 20%.
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
srb94
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Re: Lost sync all at once on good system

Post by srb94 »

Luke,
Thanks for the confirmation. This was suggested earlier and it was on my list, however since everything worked fine with no filter before I really wanted to find what was causing the problem. However, the dual pulse at the same time stamp got me thinking more about it. I just started reading up noise filters today and I agree the tach period is most appropriate for my situation.
I have some other things scheduled over the next few days but am cautiously optimistic this will resolve my problem.
From how you described it I conclude that there is no downside that you have observed. Is that correct?
Many thanks,
Steve
Steve B.
slow_hemi6
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Re: Lost sync all at once on good system

Post by slow_hemi6 »

No downside on my car with the way I have it set up.
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
srb94
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Re: Lost sync all at once on good system

Post by srb94 »

OK, update time :P . Not sure it is resolved but appears like it may be. At the suggestion of a couple of you (thanks Luke and Kaeman), I did activate the noise filter in the ignition settings. On two separate drives over a total of 10 miles I wasn't able to lose sync once. Compared to multiple lost syncs in less than a half mile I feel pretty confident. My next step is to turn the filter off and see if it comes back. If it does come back and I can make it stop by turning the noise filter back on, I am satisfied I have a solution even though i don't know what caused it to occur. However, if it doesn't come back I am not sure where to go next other than just be glad it is no longer a problem, for now. I wish I knew the source, but will be happy with a solution.

So, here are the settings I used, basically the defaults other than turning it on.
Global Timer Noise Filter Delay = 4
Noise Filter Enabled = On
Tach Period Rejection = On
Time (ms) = 0.1
Percentage (%) = 10

Secondary Cam is all Off.

I can see a good argument for a larger time and percentage number but this seemed to get the job done. I liked the Tach Period Rejection method as it seems to apply to my problem most directly and still allows log files with meaningful data related to the problem. I will let you know the results of turning the filter back off, but other commitments with the family and house maintenance are complaining that they have been put off to long so....It will be a few days.
Steve B.
srb94
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Re: Lost sync all at once on good system

Post by srb94 »

OK, the filters solved the problem. Further tests confirm the previous findings, and add some more information. With all the filter elements turned off the problem returns. With Tach period rejection on and noise filter enabled off there was nothing observed. With both on there still was noting. This implies that the tach filter rejection as the solution but I ran out of light before I got the chance to try just noise filter enabled without the tack period rejection on. I will keep this in mind going forward, along with increasing the percentage and time of the tach period rejection, but for now I am moving on to other issues needing attention. The loss of time running the car has basically cost me this season and I have lots to do to get back on schedule.
At this point I wish two things. First, I wish I had posted on the forum sooner, and second, I wish I had listened to the advice on applying the filter sooner. However, if I had done that I still would feel that I had not attempted to solve the noise issue, which i still have not done, and it was waiting to bit me later, which it may be. On the positive side, I have eliminated all of the typical and easy solutions therefore I feel it is a marginal issue that remains and I am proceeding.
Thanks for all the inputs and encouragement. It was truly appreciated. If I find anything more on this issue I will add to the post.
Steve B.
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