Blackbear Performance Review

Fless said:

If you have a bidirectional scanner and use the mfr's codes by VIN (not generic OBD) is there a fuel composition or alcohol content value, or a reset function?

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Bigburb3500 said:

So it’s been interesting. I’ve been doing a good bit of “general” maintenance (will post in the 3500 thread I have) but VIN lookup at the parts store has the question about flex fuel or non-flex fuel engine. I believe my truck to be non-flex as it was a fleet vehicle and came with a sticker “GASOLINE ONLY”.

I do not have a factory sticker indicating anything else.

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Fless said:

If you have a bidirectional scanner and use the mfr's codes by VIN (not generic OBD) is there a fuel composition or alcohol content value, or a reset function?

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Geotrash said:

So here's what I found with HP Tuners, using their scanner app. Alcohol content was not a default channel for the app's home screen, but I was able to add it and then scan the ECU to see if there was any data available there. Sure enough, there is. Now I don't know if it's a calculated value based on O2 sensor data, or an actual hardware sensor value, but at least the ECU is capturing alcohol content data as a percentage. And the value seems plausible. Note, the ignition was on but the engine wasn't running for the screenshot below.

View attachment 444783

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Fless said:

I can't imagine that there is a physical sensor on it, so I would bet it's a calculated percentage. They dropped the physical sensor from the GMT800s around 2005 or so.

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Fless said:

Curiously, gmauthority says it's FF:

https://gmauthority.com/blog/gm/gm-engines/l96/

I would be inclined to do a little test with some E85 -- know your fuel trims with E10 first, then maybe mix 1/3 E85 (probably E50 or E70 at the pump) with 2/3 gas and see 1) if the STFTs go way positive, or settle down to a good value and 2) see what HP Tuners reads for alcohol content. And not a full fillup, just less than 1/2 a tank if it becomes an issue.

EDIT: I take that back, didn't read the fine print. Article says FF in the Savanna and Express only.

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Bigburb3500 said:

What is the physical difference between a FF and non-FF engine? Maybe a dumb question but I’m wondering if the “stealth” feature is there but the difference could be injectors or something else buried deep into the truck.
Maybe?

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