Frame77

Hi,
logged my LTFTs and they are way out of line (about 20% lean).
Since I am gatting my headers&wideband mounted in october, can I correct SD and MAF tables to bring the FTs back in line without tuning WOT/PE?

Of course a full tune will be done after headers & WB are mounted.

Thx

0Tampa Tuning

With your 20% error, Make sure your either not coming off your throttle or have a mechanical issue. Normally they may be 5-10% off in the somewhat stock configuration. 20% off would be a high.

Yes you can adjust the fuel trims under the power enrichment range for better cruising, then blend that slightly into your wide open area. But, you should still want a wideband on the car if you are changing fueling parameters.
Corvette Camaro Truck Tuner in Tampa

Phil

Frame77

Have a vararam installed and a borla catback...

tblu92

A 20% swing is huge---Lean meaning that the increased airflow is making it that way
This would apply only on a basically stock engine---You can correct this with a MAF table adjustment
However I suspect you have a cam --maybe LT headers etc---All these mods especially the cam and LT's will make the lower RPM's dirty---Where MAF tuning almost becomes mute
Typically with larger cams and LT's the best thing to do to obtain a smooth idle easy starting and no surging is to disable the LTFT's entirely----Then with using a wideband you can tune in your P/T AFR's to about 13.5 to 14.68 ( either with the MAF table the IFR table VE table or idle airflow table
More info on your engine would help

Ed@TheVetteDoctors

For reason which I can't explain unless the Zo6 tune is much "tighter", it appears the C5 ZO6's react much differently (will actually throw lean codes) to the Vararam then standard C5's. If you are running a Zo6 then that could be your answer, Add 20% to the entire MAF table to be safe until you get it tuned with the next set of mods.

Ed M

Frame77

Thank you guys.
Car is a stock 98 non-Z c5, only mods are the borla catback and vararam as mentioned above. Doesn't throw codes.
However I just ordered an Innovate LC-2 wideband.

H/C and LTs will be installed during the winter, but I wanna take care of this before...

RonSSNova

How did you log this?
LTFT 20% lean everywhere?
I'd trust HPT scanner to show me visually where and when it's lean. Not a phone app etc.
Not enough info here here to declare an emergency.

Frame77

It was logged during a Dyno Run with EFI Live by a professional tuner. Wanted to have a Dyno before H/C install to see the gains.
Yes 15-20% everywhere.
I did look into it with HPTuners myself afterwards and got the same data.


Tuner said it's the vararam and told me not to hit WOT before this is tuned properly.
I'm not exceeding 3000rpm until H/C install and tuning.

romandian

something weird is going on. 15-20% more air from cai everywhere? what are the stfts and narrowbands showing?