Predator tuning for headers

[soliari]

Hello all,

I recently installed headers and a very free flowing catback. I went out to tune the AFR and what I found was incredable.

Predator PE settings before headers:
+5%

Predator O2 readings before headers:
890 millivolts

Ok, after the header/catback install I went out to get some readings on the O2 sensors. Here's what they read:

990 millivolts

I expected to be rich, but that reading suprised me.

So far, I've made several corrections to the PE setting. Here's what it is currently and also the O2 sensor readings.

PE: -.50
O2: 935 millivolts (still rich!! :eek: )

I'm going to continue to lean out the PE setting, but do headers really make this much of a difference???

For a list of mods follow this link (http://home.comcast.net/~gmartinez17) and go to my car page. It has everything save the headers and exhaust.

[JandJsTA]

You may have to contact James (RWTD) if that is who you bought your Predator from and get a custom tune from him as I would suspect that your LTFTs are off the wall rich at cruise and that is what is making it hard to control your A/F at WOT .......... Get the LTFTs at cruise under control first and the WOT will come along nicely :)

[soliari]

Right now, the LTFT's are showing -8 at cruise is that too negative??

[JandJsTA]

Originally posted by soliari
Right now, the LTFT's are showing -8 at cruise is that too negative??

Are they showing that in all cruise fuel cells 6-14 ... not an average of them all, but each one must be 0 or slightly - :confused: if so continue to work with your PE A/F ... just seems odd you are not getting a better response from your PE changes ..... have you already had a custom tune done to bring down your LTFTs .... as the norm after a header install is very high LTFTs (in most cases) :)

[soliari]

I think you may be right about the the LTFT's being rich. I just adjusted the PE to -5% and the O2's are still showing rich ... :confused:

I'll have to get with a friend and to some data logging ...

[GETSOMZ28]

Gabe, James (RWTD) said he needed to tune for my headers. As you know, we were able to fine tune it after I got the new tune in.

[soliari]

yep, but this is a "header'" tune. LTFT's are better now, -5 but I'm still showing rich on WOT ...:mad:

[soliari]

Well, I installed an old tune that I had and replaced becuase it ran lean. Guess what?? It cured my issues. The LTFT's are at -6 and WOT readings are now withing the ballpark. All with 33* timing and no KR!! It's time to hit the dyno!!

[WAHUSKER]

You guys should ignore the LTFT's @ WOT. Only read them in cruise or idle.

[smiley]

You guys should ignore the LTFT's @ WOT. Only read them in cruise or idle.

not exactly.....

if your ltrims get locked in at a + number during wot.... you have more ltrim tuning to do. most people try to tune ltrims to zero or slightly negative which will make them be zero during wot.

if they are positive the pcm is adding fuel because it thinks there is a lean condition. during wot this is not calculated. but if the pcm thinks oyu are lean it will continue to dump that extra fuel in during wot - hence ltrims being locked in on a positive number.

get all your ltrims to zero or slightly negative.... then tune wot.

[soliari]

at WOT, LTFT's are at 0 ... and O2 sensors are reading 920 ...