Urgent! High LTFT trim and extremely low IAM on a Stage 2+ tune

[alphasaur]

If you're running regular fuel instead of ethanol and you're on an e85 map your trims will be negative as the car will be running rich due to pumping in too much fuel (stoich is far lower with eth (~10 vs 14.7 for petrol). The car is being told to pump in an appropriate amount to achieve AFRS needed for e85, but it doesn't sound like you're running eth so the car is attempting to correct for it by pulling fuel.

You will also get more knock as timing is more aggressive on an e85 map.

I would add known e85 fuel and avoid going wot.

Also, flex fuel would likely save you from this event in the future.

[twistednoble]

Sorry for the lack of response I didn't get any notifications about replies.



I got home, loaded up the stage 2 tune onto my tablet, pumped 5 gallons of premium into the tank, and flashed on the tune.


Ran the test 30 mile loop I use when testing parts and all is well again. Fuel trims were +-3% and IAM went up to 1 after a normal amount of time.

Definitely not getting E85 at that station ever again.



Thanks for your reassuring words gentlemen.

[tomm.brz]

you re welcome

[blsfrs]

Originally Posted by BlOody_BoOger

So With a negative reading the ecu is saying that there isn't enough air in the mix. I guess you can say there is more fuel than air. But not because the engine is adding fuel it's because the engine isn't getting the needed air. So then the car pulls back fuel and sprays less. That's the negative you're seeing. Negative 17 mean there is 17% less air in the mix that is required to run properly. If you were seeing positive 17. Than that means that there is 17% more air and so the car adds more fuel to the mix. The car can't control how much air goes in the engine but It can control how much fuel to add and remove. So that's what it does. You could have a sensory that's reading incorrectly or correctly. But not enough air would mean something wrong with your intake. Or throttle body not opening up idk. I say as long as your afrs stays around 14.7 at idle and under cruising your ok I wouldn't go hard on it untill you find the issue.

Sent from my IN2017 using Tapatalk

Thank you. That;'s the clearest explanation of fuel trims that I have ever found.

[Jaden]

Originally Posted by twistednoble

Sorry for the lack of response I didn't get any notifications about replies.



I got home, loaded up the stage 2 tune onto my tablet, pumped 5 gallons of premium into the tank, and flashed on the tune.


Ran the test 30 mile loop I use when testing parts and all is well again. Fuel trims were +-3% and IAM went up to 1 after a normal amount of time.

Definitely not getting E85 at that station ever again.

Thanks for your reassuring words gentlemen.

You should really consider going flex fuel... I did it for about $150.

You can find my thread on it. I'd be more than happy to give you my code that I've been running for more than 3 or 4 years.

Hell I'd program an arduino and send it to you for $60...All you'd have to do is source the ECU tie in harness(or just tie it in to the evap sensor pin yourself) and a GM Flex fuel sensor and the asssociated fuel lines.

And get a tune for flex fuel. I got one from Shiv, but there are tons of options out there.

Jaden