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

Hello, I'm rocking a 15 BRZ with a Stage 2 E85 tune. Aftermarket catted headers, cutback, and no intake mods. I've been running with this for about a year now with little issue.

On my last fuelup I got a really rough start the following morning. I checked to make sure I didn't get a mouse in the filter and then plugged in my oft to check things. Lo and behold I have a LTFT of -17% and a IAM of .84. Ambient temps are in the 40s F.

I wasn't immediately concerned but I am on my way back home from visiting family for the holiday so I dont have much option but to watch it, pray, and baby it home. I'm now taking a rest stop and I've watched it jump between -17-12% on LTFT and IAM has slowly fallen .64 to .43 and now is down to .34. KC has hovered around 0-1.

If I hadn't noticed the rough start I probably wouldn't even known there was a potential issue. The car isn't down on power and doesn't sound weird currently. Fingers crossed. I'm almost sure that the last station I filled up at gave me some E85 with a really low E% and that is where this is coming from.

Am I in serious and immediate danger of catastrophic damage? I have a Stage one tune handy should I flash back to that or stick with the Stage 2 for the remaining 40 miles home?
I've got about 3/4 of a tank remaining so diluting the crap out of it with some premium isn't really a strong option either.

Thoughts?

fill with gasoline and put stage2 for petrol
drive slow for a bit to settle ltft, won t be a huge problem and you ll have conservative timings

I'm not sure if I have the stage 2 petro tune handy is the stage 1 usable in it's place?

High ltfts are indication of too much air not enough fuel when you have positive trims it means that there is that much more air in the system so the car adds fuel in your case it's pulling back fuel alot. Low iam is indication of bad fuel you could always add some e85 booster to help stabilize the fuel in your tank. Other than that maybe doing a data log while running the car and having some of the tuners here on the forums look over it just to be on the safe side. https://uploads.tapatalk-cdn.com/202...0fa62217e2.jpg

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Also reflash your e85 tune

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Not a high trim, that's a negative 17% trim. So too much feul not enough sir. I've tried that particular fuel treatment and it makes the car incredibly hard to cold start when it's below 40f.

Hunting premium now. LTFT -21 IAM .25. Only finding 87 so far.

That's what I'm saying, when my car was running positive trims. I had a vacuum leak so the car was reading excess air in the O2 sensor so naturally the car added fuel giving me positive trims. In this case there is a negative trim. So the car is pulling back fuel causing a negative trim. Ltfts are the ecu making adjustments to the fuel trim levels. If his afr is still at 14.7 then it's safe to say the engine is doing what it can to get that ratio this rules out faulty injectors and fuel pump. Because they're working just fine. Check your afr at idle and under light throttle.

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Wouldn't a negative LTFT indicate the car is getting too much fuel not enough air? And a positive LTFT indicate the car is getting too much air too little fuel?

At idle it's holding 14.69:1
Light revs fluctuates down to 12ish:1.

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.

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Alright, I'm going to drive the last 20 miles home then. If I had the proper tune handy for gasoline & aftermarket catted I would dump in more premium and flash it but there's too much uncertainty to make changes that may or may not help.

I really should have worn the brown pants today.

Reflash your current tune it will reset your trim levels and that should help for a lil.

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Not gonna try that either. Sticking with what's on there for now. It's gotten me 60 miles and it will get me the last 20. My primary concern is running a whole hell of a lot of timing on fuel with insufficient E%. The .37 IAM should keep it scaled back until we pinpoint the issue (be it fuel or sensory).
The ECU knows best until it doesnt.

you have no leak

you have low ethanol for your e85 tune, stage2 petrol will have good timing and present high ltft but it will work ok

stage1 will have probably more positive ltft but lower timing.. it is good, it s just slower

running with e85 tune as you are now, it is mote risky
But if you drive slowly nothing happen.. you are NA, nothing will happen.

What is your E% at?