Lost Sync

[vwi_dduvall]

Hello, I have moved to sequential spark and it runs great, well almost. Took it for a drive around the block and it does well till the rpm gets higher, guessing around 2k or more then it acts like it shuts off, even get a few clicks of the relays. To through something in to make it more interesting if I turn on the running lights and headlights the problem worsens and drops to a slightly lower RPM where it happens. I am attaching a link to a zip file for those who want to take a look at the logs it contains all that I think is necessary to do so.

http://volkswageninsanity.us/Postings/FI/Tune&Logs/ZIP/

Thanks in advance for any pointer that might point me down the right road.

[Chip Birks]

Did you post on msextra?

[vwi_dduvall]

Did you post on msextra?

Have not.
Assume your talking here: http://www.msextra.com/forum-info/

[vwi_dduvall]

Found this: http://www.diyautotune.com/tech_article ... _index.htm

My problem sound much like this where they recommend Putting a 10K to 20K resistor inline.

I am using the Redline cam trigger.

[Chip Birks]

The dudes that developed the hardware and firmware of your ms3 are all over those forums. They are a very valuable resource.

[vwi_dduvall]

OK more info to help in the diagnosis. Looking over logs that I ran with my laptop not the SD CARD it was logging the lost sync count reason:

2 = missing tooth at wrong time

The link posted previously states:
"What starts as a small noise spike at low RPM becomes a very large noise spike right in the spot where the missing tooth is, causing the ECU to lose synch. You'll see this problem manifest as the RPM signal suddenly spiking downward at high RPM, and the car acting like it's hit a rev limiter. Putting a 10K to 20K resistor inline with the crankshaft position sensor wire generally clears this right up."

[Piledriver]

The downside of a VR sensor is that as RPM goes up, so does the signal voltage.
(it is essentially a basic alternator of sorts)

The flip side is that the signal at cranking speed has to be high enough to work reliably, so sets a minimum threshold.

Adding input resistance may work, but it can also perversely increase susceptibility to line noise by increasing the input impedance.

I know in MS2 simply turning on the built-in CPU hardware filters can do wonders, have not run into an issue with MS3, but my setup is violently non-supported.

[vwi_dduvall]

As far as sensitivity I was quite surprised at how much this unit is. A slight movement of the shaft causes the ECU to turn on the pump. Not sure if that is normal or not.

[Clonebug]

How much gap do you have from the sensor to trigger wheel???

[vwi_dduvall]

How much gap do you have from the sensor to trigger wheel???

Not much will have to get my feeler gauges out to see but there is no room for adjustment far as I can see.

[vwi_dduvall]

How much gap do you have from the sensor to trigger wheel???

Not much will have to get my feeler gauges out to see but there is no room for adjustment far as I can see.

About .011 or .279mm

[Piledriver]

Play with the pots first, also don't hesitate to play with the noise filter...
Try both and try a ferrite before adding external components.

if you used shielded twisted pair wire ground the shield at one end only.

[vwi_dduvall]

I am not sure what i will look for when adjusting the pots. I did what was recommended and zeroed them out.
When I was tinkering with them at first it seemed that it was where it worked best as I could not start at .5 of a turn and was able at only a .25 of a turn so left it there. I have just now zeroed it out again. How do you make these adjustments with the expansion board in the way?

I used the shielded cable you recommended and grounded it at one end.

[Piledriver]

I have just now zeroed it out again. How do you make these adjustments with the expansion board in the way?

A little bit at a time.
One of the pots reduces the sensitivity...

Adjust the pots as best you can per the procedure, then try the inline resistor.

You should only have to do this once.

[vwi_dduvall]

OK turned on the noise filter and first try just made things worse using the default setting.
So went and set things like Piledrivers with a little improvement noticed.
Since I am not sure how to work this adjusting it is a bit daunting.
Any input or pointers gladly appreciated.


Link to .tsprog:
http://volkswageninsanity.us/Postings/F ... gs/tsprog/

Link to Logs:
http://volkswageninsanity.us/Postings/F ... Logs/logs/