cylinder airmass randomly drops to zero during pull

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08-03-2021
GATEKEEPER

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cylinder airmass randomly drops to zero during pull

2011 CTS V, FBO, cam, full fuel system, E85

During a pull today the car bucked violently so I let out. Luckily I was logging when it happened. Once I got home I checked the log and saw that:

- Cylinder airmass drops suddenly to zero
- Ignition timing shoots up to 54*
- Injector duty cycle drops to .5%

All this happened at once and only for a split second before returning to normal.

Car has been driving perfectly up until now. After the pull, every now and then I would feel the car cut out like a misfire but I couldnt see any indications on the log- just the wideband go lean for a second before returning to normal.

Any ideas on what to look for?
Attachment 112227

File
Attachment 112228
08-03-2021
kevin87turbot

Were you datalogging MAF freq? Did it go to 0?

If so, I'd check for a bad or loose connection at the MAF. If it continues doing it, you might even replace the MAF.
08-04-2021
01SLPSSM6

You have your MAF failed and dynamic air set to 4000 rpm. Any reason you have the MAF table zeroed out?
08-25-2021
GATEKEEPER

Quote:

Originally Posted by 01SLPSSM6

You have your MAF failed and dynamic air set to 4000 rpm. Any reason you have the MAF table zeroed out?

Sorry for the late response. Last minute work trips tend to throw a wrench into things lol

So are you suggesting that I populate the MAF table, raise the dynamic airflow enable to say 8000, and lower the enable down to something like 100 RPM?

I guess I never mentioned that I am running this car in Speed Density if that matters
08-25-2021
sevinn

Quote:

Originally Posted by GATEKEEPER

Sorry for the late response. Last minute work trips tend to throw a wrench into things lol

So are you suggesting that I populate the MAF table, raise the dynamic airflow enable to say 8000, and lower the enable down to something like 100 RPM?

I guess I never mentioned that I am running this car in Speed Density if that matters

If maf is present populate the table.

Airflow enable: 8192
Ariflow re-enable: 8191

Make sure your maf diagnostics will fail (set fail hi to a really low hz, and fail lo to a really hi hz). P0101-p0103 to mil on first and I'd uncheck ses enable so that you don't have to look at the light.