Thread: Tuning help

So I recently got the dual aeroforce gauges and am learning how to read the fuel trims to see how close my can tune is. The stft seems Okay it's always normally - but not anymore then like -3 to -4 most of the time it's at 0 or closer. My ltft is kinda messed it seems like it fluctuates alot under wot I got a 0.0 stft and a -0.7 ltft but under hard acceleration ltft is like at -8 to no more then -12 is that bad? BTW it's a top swapped cammed 2000 grand prix gt mods are in my signature. Help is much appreciated!

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Short term trims rarely matter because they switch so fast, they are like the up to second changes that they make on the fly.

A long term trim of -8 to -12 means it's got a more fuel that it needs for what you are commanding, you can lean it out a little and see how much closer to zero they come.

I don't have a tuner I just wanted to make sure it's safe and decently close. How come at idle my ltft is at -20 consistently?

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Likely because the MAF still needs to be tweaked in that area, even changing the VE table in the idle area could bring it in closer to zero.

Bigger/different MAF's can require alot of tweaking to get everything in line, that's where having your own tuner is very handy.

I had zzp tune for a N* LQ4 could that be why? So is this like way off? It's been this way for a while seems to run pretty good.

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ZZP can't tune for those mods with even a chance at being correct 100% of the time.

So many other factors come into play with this. Air temps, altitude, engine health and a bunch of other stuff. No car will ever be the same and that's why fine tuning is needed for a swap like that.

-20 at idle is really far off but it's not doing any damage and won't. Your trims at WOT aren't ideal but you seem to not have any real problems there.

Okay thanks for the info I appreciate it. Is there anyway now I know what it's running they can tweak the pcm by leaning it out if I sent it to them? Will it run night and day better if its tuned correctly? So basically it's just really rich right? I feel like that's why my idle isn't as consistent as it should be it's not horrible but I feel like it tends to get loaded up when it sits at idle like it wants to go lol.

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I don't think much will change if they the trims were much closer, it's not going to gain you any power or anything like that.

I wouldn't have them do anything to the computer because they aren't actually infront of the car with that laptop. They would just be guessing and leaving you with whatever they think is right, might put you worse off. Stuff like this needs to be done in car with logging and driving to relearn trims after any changes are done.

Okay what are ideal fuel trim numbers? What's the best way to read the trims on the aeroforce wot?

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Would it be safe to drop from a 3.4 to a 3.3 pulley with those trims and 0kr?

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I think you already know those questions.

Zero on the LTFT is ideal, or within 3ish percent. You are already logging trims on your aeroforce, so you have that covered. How else would you have started this thread.......

I meant like +3%? + is lean? - is rich right? Seems backwards to me this is all new to me I don't mean to sound repetitive just don't want to mess things up. Do I have to reset unplug the computer or just throw a 3.3 on it? Could my trims possibly get better by dropping the pulley?

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If zero is the target number, then yes a +3 is lean and -3 is rich. But that does not mean it's a dangerous condition as the computer is more than willing to compensate for the error it's seeing.


If everything was in line and you saw a very positive number like +16, that mean unmetered air is making it's way into the motor and causing a lean condition.

Swapping to a smaller pulley isn't going to really change the way the MAF sensor is still calibrated. It's still going to be a negative number on the fuel trims.

That is the % error that your car is reading from the o2 sensor to correct the afr at closed loop. They aren't showing that you are running lean/rich.

If you aren't getting any kr, drop pullies until you do. The pcm is a lot smarter than people give it credit for.

all you can do is try the 3.3 due to the fact you dont have a tuner. for real tho, buy a tuner, canned tunes are not custom to your cars needs, with the ltft being that rich wot you could be washing any kr with all that fuel.

it needs the maf fine tuned for sure.

Everyone says something different lol so since it's so rich maybe I wouldn't want to drop pullies untill I get a tune? How could there not be any actual horsepower gains from a tune?

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lean is mean dont ya know. you got a wideband on it yet? that will tell your true a/f when wot.

being you have a canned tune, all you really have to do with a tuner is dial in your maf, drop your pulley then play the timing game depending on if you get kr.

Everything said sounds the same to me. The tune is rich, the computer is fixing it for you. It's not ideal but it's working.

If you have a wideband you could see what your WOT fueling is, likely it's on the rich side.



Any gains to be had will not be noticable, we aren't talking like 20-30hp here. Maybe like 1-5hp if that if you took some fuel out on setup like this.

You literally have no idea if it's rich or lean unless you put a wideband on it.

Lol I know lean is bad that's why I was kinda tweaking for a minute because I thought - on the aeroforce is lean. So the computer compensates for you?

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