How much power left on the table with ~10:1 AFR

[hmg_57]

Good evening,

I've been datalogging my father's Ford GT lately in an attempt to improve the fuel pressure stability on my 2003 Cobra. Just looked at the logs today and, even though no wideband is hooked up to the car, I noticed that the STFT's were showing a commanded lambda of 0.685 at some point.

We're really wondering how much power he's leaving on the table with a ~10:1 target AFR from 4500+ RPM...

Thoughts from people with tuning experience would be greatly appreciated !! :cheers

 

[TEXAS GT]

Lambda Murci or Gallardo?


Sorry.:biggrin

 

[tmcphail]

If your referring to WOT and you don't have a wideband involved you can't monitor the short terms to see where AF actually is. Your in OL so narrow band 02 feedback isn't happening.

 

[hmg_57]

I am aware that the ECM doesn't monitor the factory O2 sensors during Open Loop. We do not have a wideband hooked up to the car right now but, from my understanding, the STFT's indicate commanded lambda that is derived from the base fuel table during OL.

SCT tech support confirmed that the base fuel table should be targetting 0.82 at WOT which means we're probably entering cat overtemp protection. Why would the car get into cat overtemp protection as early as 3rd gear on the first WOT pull of the day ???

 

[Fast Freddy]

Good evening,

I've been datalogging my father's Ford GT lately in an attempt to improve the fuel pressure stability on my 2003 Cobra. Just looked at the logs today and, even though no wideband is hooked up to the car, I noticed that the STFT's were showing a commanded lambda of 0.685 at some point.

We're really wondering how much power he's leaving on the table with a ~10:1 target AFR from 4500+ RPM...

Thoughts from people with tuning experience would be greatly appreciated !! :cheers

with a 10:1 A/F ratio i would bet that you are leaving close to 10% power on the table. lean it out and burn some rubber but don't lean it to much or you will burn some pistons up :thumbsup

 

[hmg_57]

So, looks like we're down 40-50rwhp ? :willy

 

[hmg_57]

Well, further datalogging showed that the base fuel table is commanding a target lambda of 0.82 (12:1 AFR) but "Inferred Exhaust Valve Temperature" is forcing the PCM to switch table and command 10:1 AFR !! I can't believe this protection kicks in as early as half way through third gear when leaving from a dead stop. Is this normal ? If not, what do you think could be the problem ?

Thanks for your help !!