I have a ? about the LTFTs.

First off, car is a 2002 M6 WS6 TA. Only real power mods are a direct-flo lid.

I just added Tbyrne MAF ends to the car. I also have a MAFT and EFI Live. I went out logging before the MAF ends and the LTFTs averaged about -3 or so.

After putting the ends on it was running pretty lean....about +9 or so on both sides.
After a little trial and error...at 10% rich on the MAFT one side is lightly negative and the other is sligtly positive on the LTFTs.

I bumped it up to 15% rich and they both read slightly negative of about -3 or so on average.

Should i go with the 10 or the 15?
TIA

 

If I were you, I wouldn't goof with it at all.

Your LTerms are not bad at all. It is not uncommon for a totally stock car to have slightly positive LTerms.

The whole point of MAF ends is to lean the car out slightly and increase timing slightly by tricking your computer into seeing less air. A stock car comes from the factory with a ~11.9:1 a/f ratio. Ported ends will usually lean this out closer to ~12.5:1 a/f. Cars make the most HP at a 13:1 a/f ratio. Your car is going to make more HP at a 12.5:1 a/f than a 11.9:1 a/f ratio.
True, the positive LTerms are going to have the car add a small percentage of fuel at WOT, but the net fueling at WOT is going to be less (hence the leaner a/f ratio) due to the ends reporting less airflow than with the stock MAF.

In addition to leaning out your a/f ratio, the MAF ends will report less air flow and actually increase your timing at WOT. This is much more true for 01 and 02 cars due to their lax timing table.

By you adding 10% or 15% more fuel you are actually correcting for what the ported MAF just did. Not only are you going to return fueling back to normal, but you are also going to return your timing back to normal. The net result is going to be less WOT hp.

I would live with the +7 LTerms (they ARE NOT HURTING YOUR CAR) and leave the car alone.

Good Luck,
Kevin

 

So running +9 lean isn't going to hurt the car at all?? Just wondering because with just the lid it was a good bit negative.

Also after what i did 15 rich base and 2 lean WOT EFI Live shows my AF ratio at 13.0.
thx for your help <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Also with just a lid i'd get 3- 3.5 KR

With 15 % rich base:
WOT not touched :.2KR
WOT -2: 0 KR

0 KR is good right?

 

The a/f shown on EFI live is not accurate. The only way to measure your a/f ratio properly is to hook it up to a wideband O2 sensor on the dyno.

Just for an example: I usually don't pay attention to the a/f ratio reported by the scan tools, but just for kicks I logged it the other day while dyno tuning a car. The reported a/f ratio on the scantool was 11.6:1 while the actual a/f ratio of the car was 13.0:1.

Good Luck,
Kevin

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by JamRWS6:
<strong> Also with just a lid i'd get 3- 3.5 KR

With 15 % rich base:
WOT not touched :.2KR
WOT -2: 0 KR

0 KR is good right? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Okay, KR throws something different into the equation. If you are getting KR, then I would tune the KR out of the car.
KR, not always, but can be used as an indicator that the car is running too lean.

 

thats interesting then that when i leaned out the WOT the KR disappeared.

 

Leaning out motor doesn't get rid of KR unless it is a rich KR, in which case, the motor has to be so rich that it is drooling fuel out the tail pipes. More than likely, it was just not repeatable KR. The intensity of KR changes with every run. More than likely, your KR would have not showed up despite your changes to the MAFT.

.2 KR is very very small. Anything less than one is usually dismissed as 'noise'.

Did you have 3 to 3.5 KR with the lid and the ends, or with just the lid?

 

The 3 to 3.5 was with only a lid.

I wideband O2 would be nice to tune on but I don't have one readily available. I can't really tell if the car is running stronger or weaker than it was.....i guess a track visit would be able to tell me.