How much do Ltrims affect HP?
Thread Starter
Staging Lane
Joined: Apr 2002
Posts: 62
Likes: 0
From: Artesia, NM
How much do Ltrims affect HP? Just finished JP's S2 heads and tr224 cam in my 2001 A4. Only picked up about 35-40rwhp, but my Ltrims peaked at about +17 averaged 14-15. Joe and Dennis is in the process of getting a new pcm sent to me since Ed wright really messed things up. How much power can I pick up from getting the Ltrims down to about 0? Thanks for the help.
Re: How much do Ltrims affect HP? No HP differences in LTrims unless you are maxing out your fuel system delivery. LTrims just tell you how hard the PCM is working to correct the tuning.
Tony
Tony
TECH Addict
Joined: Nov 2001
Posts: 2,207
Likes: 0
From: College Station, Tx
Re: How much do Ltrims affect HP? If you are running extrodinarily rich at WOT and the l-trims are adding more fuel it can rob you of power. If you are running "lean" at wot and the l-trims add in fuel to correct this they may be actually helping you.
As tony pointed out, l-trims in and of themselves have do direct correlation to hp output.
Chris
As tony pointed out, l-trims in and of themselves have do direct correlation to hp output.
Chris
Thread Starter
Staging Lane
Joined: Apr 2002
Posts: 62
Likes: 0
From: Artesia, NM
Re: How much do Ltrims affect HP? I was under the impression the at WOT the Ltrims told you whether or not you were running lean or rich??? My o2's are in the low 700's and the Ltrims averaged about 14-15, SA was about 28-30 and 0 knock at all points in the rpm band, don't know what Ed Wright did to my pcm.
Staging Lane
Joined: Feb 2002
Posts: 97
Likes: 0
From: Newport, Michigan
Re: How much do Ltrims affect HP? Nemisis,
The Lterm fuel trim values indicate if you are tending to run lean or rich while at part throttle which I call "cruising around".
If the Lterm fuel value is positive like yours, the PCM will add that % of more fuel in at WOT. Your PCM is adding in 14 to 17% more fuel in at WOT.
If the Lterm fuel value is negative, like -5%, the PCM sets it to 0% when at WOT and does not take out fuel or add more fuel in while at WOT.
If you have a MAFT, try setting the base at 20% rich and the WOT switch to no change, do a PCM reset, and go out and drive your car around for at least 20 minutes. Then take some readings while cruising around to see where you are for Lterm fuel, and take some readings at WOT to see the O2 sensor output. You want to get your Lterm fuel values below 0%, then you can more directly control the A/F ratio at WOT because the PCM will not be adding more fuel in from the Lterm value.
The Lterm fuel trim values indicate if you are tending to run lean or rich while at part throttle which I call "cruising around".
If the Lterm fuel value is positive like yours, the PCM will add that % of more fuel in at WOT. Your PCM is adding in 14 to 17% more fuel in at WOT.
If the Lterm fuel value is negative, like -5%, the PCM sets it to 0% when at WOT and does not take out fuel or add more fuel in while at WOT.
If you have a MAFT, try setting the base at 20% rich and the WOT switch to no change, do a PCM reset, and go out and drive your car around for at least 20 minutes. Then take some readings while cruising around to see where you are for Lterm fuel, and take some readings at WOT to see the O2 sensor output. You want to get your Lterm fuel values below 0%, then you can more directly control the A/F ratio at WOT because the PCM will not be adding more fuel in from the Lterm value.
Thread Starter
Staging Lane
Joined: Apr 2002
Posts: 62
Likes: 0
From: Artesia, NM
Re: How much do Ltrims affect HP? If I had autotap and MAFT then I wouldn't have any problems or even LS1 edit!!! But I'm stuck right now with Ed's crappy tuning and short shifting pcm! The first shift comes in at about 6000 and 2-3 shift at 6200. Joe Prince and Dennis are working on getting another pcm to me and I will send this one to them for a core. All I was asking was how much power am I loosing because of the shifts and tuning? Sorry it's late. Thanks everyone. Previous best in average weather was 12.93@106, best is now in sig.
