Thread: Special Thanks & Weird -25% LTFT

Special Thanks to Darkhorizon for trying to tune my car. Unfortantely I'm pulling -25% LTFT and I have no idea why. What he was able to do is much appreciated. I'll attempt to figure out why the car is doing it. Thanks again man!

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prob cause he does not believe in modifying the MAF table.... But seriously do you have a data log or bin file i could give it a look.
but yeah a -25% LTFT something is not right. Is this at WOT or cruse? Obviously the computer thinks its getting way too much fuel. what does the wide band read? how much fuel are you really seeing. Did you change injectors on it? fuel pump? any misfire codes in the system?

Originally Posted by Z34Phoenix

prob cause he does not believe in modifying the MAF table.... But seriously do you have a data log or bin file i could give it a look.
but yeah a -25% LTFT something is not right. Is this at WOT or cruse? Obviously the computer thinks its getting way too much fuel. what does the wide band read? how much fuel are you really seeing. Did you change injectors on it? fuel pump? any misfire codes in the system?

I'll post up a bin and a recent scan in a minute. - 25% is while cruising. Injectors are stock as far as I know. Fuel pump was changed by previous owner about 6months before i bought it. No misfires at all.

Only code is a p0446 in the evap system for a blockage.. Basically I can't fill up for ****.. I have to unhook the purge solenoid on the blower so I can squeeze the handle 20-30%

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Heres the Scan

https://www.dropbox.com/s/2yg66m7tnuxjgbe/flinthome.hpl

Heres the Most recent bin


https://www.dropbox.com/s/q045nsy16kc4vyd/73113BIN.hpt


Those are Dropbox, only way I could figure out how to post them. Thanks!

MAF won't cause it to be that far off.

First thing I would look at, is your IFR table.

Injector flow rate? Already x1.06 for 6% "bigger" injectors didn't seem to make any difference

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So basically I just need to dial in the fuel trims? (disable pe, reset trims, go for a 30min drive while scanning, then adjust the maf, flash and repeat until they are within 5%..?)

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Originally Posted by rperry435

Injector flow rate? Already x1.06 for 6% "bigger" injectors didn't seem to make any difference

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What injectors did you swap to?

I didn't swap any injectors they are stock as far as I know. Tried to make the car think they were bigger so it would spray less fuel or at least that's what It would do.

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Originally Posted by rperry435

So basically I just need to dial in the fuel trims? (disable pe, reset trims, go for a 30min drive while scanning, then adjust the maf, flash and repeat until they are within 5%..?)

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Correct,with the exception of disabling PE, that is how 90% of people tune these cars. I have seen posts by DH where he makes a good point that since the MAF is stock you should use the stock calibration file and adjust Inj flow, base/PE fuel settings to get the trims to dial in. It all comes down to there are a few diff ways to tune these cars.

The most common logic is:
[If one has access to a wide band I normally adjust the inj flow so that commanded AF is very close to actual AF. they will never be 100% as they are using two diff types of sensors. once close, next dial in maf so that the trims lock in between + - 5% at cruse, then zero at WOT. Next get your WOT af adjusted to the desired AF and retune to get trims back to zero if they have drifted. If any KR is present you may need more mods or to lower timing. if no KR, its time to add timing or pulley drop.] this is basically tuning in a cliff notes version.

In that hpt file the injectors have been changed from stock and so has the MAF. So it would be a good idea to start with a stock file again and rework the tune. Also if you have a known issue such as the P0446 I highly recommend fixing that first as if it is being caused by a vacuum leak it will make tuning much more difficult. If it is a short causing the vent to open and close at incorrect times, it could also be causing tuning issues as well. get that figured out and fixed. If you don't have emissions inspection where you are maybe for the time being block off the engine side of the evap and just vent the tank to the air. see if that helps any in the tuning process.

Ahhhhhh.....I understand.

I can't imagine why your car should be that far off. Hell, the stock IFR table for the comp G in my sig was almost dead on. Your O2 seems to be working fine as well. Any possible mechanical issues?

In the starting hpt thread I thought it said something about disabling PE to get correct LTFT's?

I know the IFR was modified but I thought we had a stock maf table loaded.. I'll have to import one i guess.

I've already replaced several evap parts and its a blockage in the evap canister I believe I just don't want to fork over the cash to get a new one. We don't have evap or inspection here in michigan so what all do i have to do to plug off the engine and vent the tank? I'm sure I can look into it.

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Originally Posted by GTPpower

Ahhhhhh.....I understand.

I can't imagine why your car should be that far off. Hell, the stock IFR table for the comp G in my sig was almost dead on. Your O2 seems to be working fine as well. Any possible mechanical issues?

That's exactly what DH said last night like something mechanical is bad but I can't find anything yet.

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I have LTFT's disabled just using STFT and MAF, I honestly dont see why you just dont tune the maf table but diffrent folks diffrent strokes, for the evap just just set it to no error reported vent your tank and block at the blower.best of luck

edit one of the better writeups for your knowledge base HPTuners Tuning Basics

How did you disable LTFT on an 04+?

I'm going to tune the maf table I have had it within 5% a few months the ago.

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Originally Posted by Kyne

If the MAF is stock along with the entire air intake tube you should be able to use the stock MAF table. If there is any adjustment at all then the stock MAF reading will be skewed. Add an aftermarket intake, move to MAF, rotate the MAF, it can all change how it reads. The injector flow is a characterization of the injector and doesn't change (although you can obviously scale it but you are adjusting airflow as well so it's still the same ratio) so why would you change injector flow when you know what the injectors actually do flow and those numbers are more reliable than what the maf calibration is.

It comes down to your airflow being off, so adjust what is telling you how much airflow you have. Your fueling isn't off. So I don't think that is a good point.

Adjusting the MAF table will adjust other things as well. I agree that it should be adjusted some, but having to swing it 25% isn't the correct thing to do. He may see some issues from that.

Yes I have a fender well intake and I'm sure the position of the Maf is not stock, I will adjust the table. I've had LTFT's within 5% by adjusting the maf table (before the new intake, 3.6mps,104s and 10.5zzp wires...) so not sure how in the hell it's swinging -25%. I put then injectors back to normal stock IFR table for now. Pretty much starting from scratch to start dialing in the fuel trims again.

Also I see in the starting hpt thread it says something about timing not being over 40° in the cruising portion of the table and its something I haven't adjusted but it shows 45-47 in a few sections is this okay?

Anyone have a tuned Compg bin file? Just curious to see differences I know every vehicle is different.

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