Hello everyone.
I was wondering if anyone knew if a constantly high LTFT is normal for a boosted and tuned car?
It doesn't throw a code.
STFT Is literally NEVER bad, and stays within a single percentage point 90% of the time.
Sometimes the readings won't even register on my scanner, and it will "error out" as well.
It's been running fine for 70k miles on the same tune and boost.

It runs perfectly fine, gives gobs of power, and I trust the tune that's on it now, since it's a ridiculous beast,
but I just wanted to confirm for educational purposes, and/or if there might be something wrong somewhere.

I just have a basic OBD2 scanner as well.
I can't get actual AFR readings, which is where I think that I will be seeing if it's actually running lean, or if it's not.
I could invest in a scanner now, or I could also just leave it alone and get the scanner later.

My guess, since it gives me literally zero problems and drives like a normal daily driver with POWER above 3000ish RPM,
is that it was purposefully tuned that way to account for the turbo.
I can't imagine a tune "going bad" since it's software, and a tune lasting at least 50k miles with a 50% increase in power , while reliably DDing, so I'm very much leaning towards it being fine and just
reading weird on a scanner due to it no longer being a normal ECU.

I know that lot's of kits can run on stock injectors, but it will maximize those injectors, which may read from a scanner as "LOT'S OF FUEL BEING DUMPED", or "CAR RUNNING LEAN AND NEEDS MORE FUEL".

Is that correct, or am I wrong and should I get it looked at by a tuner again?
Should I get a scanner now, so that I can constantly monitor the AFR readings and "educate myself" on readings that are with turbo,
or should I leave it alone until later?

Thanks!

 

Start with listing what you do have.

and if dont even have a wideband, to even gauge the tune. You shouldnt be worried about any kind of fuel trims

 

We are going to need more info. What engine and year? What turbo? What tuning software?

No power below 3k is more a function of the size of the turbo and not so much a tuning choice.

Generally single digit long term trims are perfectly fine.

 

Thanks for responding everyone.
I have a confession to make.
I don't own a Honda.

I am awaiting mod approval for my particular vehicle's forum, and it's taking a while.

I figured that general information about fuel trims on boosted cars would be the same.

In either case, I've actually been able to monitor my AFR, and I figured I'd leave this here to put some "closure" on this thread in case anyone were to read it.

It's actually at perfect stoich (1 lambda) throughout most of the normal driving rev range.
When the boost kicks in, at 1/3 throttle, and you start to hear the spool, it gets down to .85.
As soon as I let go of the throttle, it will hang at around 1.3 for a bit, and then go back down to 1.

Using an AFR conversion chart, and after some research, all of this seems normal, and 11ish AFR (.85 lambda) is what people seem to agree on as an ideal AFR under boost, or even under WOT with a tune.
The 1.3 scared me for a bit, but I read that when you let off the gas, the injectors essentially shut off, so it's normal to have that situation.
It's repeatable and consistent.
It also happens when I "engine brake" (leave the car in gear with my foot completely off the throttle), so I stopped doing that because I don't want to run lean for any extended period of time.

One thing that sticks in my head though, is that the throttle plate also closes alongside the injectors closing, but at the same time, it has to stay open to some degree, since the engine needs to breathe, so it makes sense that it's lean for that 1-2ish seconds.

Now, there COULD be a small air leak somewhere, with the engine being able to compensate for that and still keep a good stoich, but I'm also thinking that the tune just using that fuel trim for some reason.
Before I do anything drastic like a smoke test, I think that I can check for vacuum leaks through my scanner by comparing the barometric pressure to the litre thingy or whatever.

However, it's also been running for 60 hours under the same scan, so I might just be able to keep an eye on it and/or use some datalogging to see if it changes for some reason whenever I get my fancy scanner.