VCM Scanner not showing RPMs above 3400

I'm a rookie tuner, but I've done a half dozen tunes successfully so far. This one is behaving differently.
Engine/Trans and PCM is from a 2003 Express Van. 6.0L/4L80E.
I've been chasing the SD Tune a lot longer than I should, but getting there.
I did a few full throttle pulls today. The RPM readings on the VCM scanner never go above 3400 or 3600 RPMs. Engine is revving fine. Can even bounce it off the rev limiter, but the scanner never reads it.
Snap-on scanner reads it fine, so it's not in the PCM. It doesn't seem to be an update-rate problem, but the longer I use the scanner the buggier it gets.
An increasing number of PIDs disappear from the recording. Eventually it locks up entirely, but I can live with that.
What I do need it to do though is log high RPMs so I can get my shift points and WOT fueling dialed.
Any suggestions?
Scan file and Layout attached.
Attachment 89942
Attachment 89941

Joe

Not to ask a stupid question but have you tried removing the channel, re-poll for supported parameters while connected to the vehicle, then re-added the channel back in?

Also, any speed density tuning the MAF unplugged and the IAT sensor reading -38 degrees will have all your data incorrect. You can't get accurate calculations if the vehicle thinks you live at the north pole. Leave the MAF plugged in and just fail it in the tune. Or if the MAF is gone you must wire in a separate IAT sensor before going any further with tuning.

Thanks for the reply. I've done a lot to get the data to appear correctly, including using 2 different laptops. The software is WAY buggier on Windows 10 than it is on Windows 7.
To answer your question directly, I have re-polled for the Data. It doesn't help the RPMs to read over 3400 though. It is definitely an interesting bug.

As far as the MAF disabling goes, I have tried it both ways on this truck. It didn't seem to make any difference, but it's easy to do, so I'll go back to doing it that way.

Joe

I am having the exact same issue and it's driving me crazy. Please update if you find a solution.

Someone just tell me this is or isn't normal. See the linked vid.
If you try to scan the vehicle with the engine running, all you get it OBD2 data. No OEM PIDS.
You can try to repoll but the choice is greyed-out, and you can't click it.
If you scan it Key On Engine Off, you don't even have to repoll, it just grabs the rest of the data like it should.
This is a bit of a pain in the butt. When tuning it's nicer to have the O2 and trims working before you begin to record data. That way you don't have zeros in the boxes before the system is active.
The vid shows what I'm talking about. At the 1:30 mark or so I shut the engine off and it works as designed.
I've got an open tech support case on this with no progress yet.
I've now tried it on 3 different laptops running 3 different operating systems.
My Snap-on scanners work without any troubles on this truck, so it's not the vehicle.
Any help appreciated.

https://www.youtube.com/watch?v=5ClP-aV2Xso

Joe

Quote:

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Originally Posted by Imadeus

I am having the exact same issue and it's driving me crazy. Please update if you find a solution.

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Does this happen to you on more than one vehicle? Every other vehicle I have tried so far seems to work as designed, but this one lq4 does it every time. I had to use a different scanner to tune WOT. It was a pain.

Joe

Update: These errors are fixed in the latest Alpha firmware update for the VCM.
I'm sure the repair will make it into the next version of release software.
Joe