Air/Fuel Ratio Good??

[NightRide]

Ok, I've been doing alot of data logging on my car lately and would like to have a better idea on what to look for. I took my two afr banks times 14.64 to get the values. At Wot my throttle measures 81% and afr at low rpms is in the low 12s. When the rpms get closer to redline it goes into the 10.3-10.5 range. Does this sound good and what are the good ranges? Don't want to ask a question that's been asked before but I couldn't find any old threads on this either. Feel free to educate me on the good afr range at WOT.

 

[Robertt305]

Mid 10's sound rich

Can you post a log?

 

[cluscher]

Yes, rich. Need to lean it out a bit. How do your plugs look? Safe and ideal is around 11.6-11.8 at WOT.

 

[Posi]

I shoot for 11.6 in my own car.

 

[ad445]

I think it should be between 11.2-11.6
Last time i checked mine it was 11.4

 

[rlhay2]

I would advise against making tuning adjustments based on the OEM O2 sensors. They are typically only accurate in a very narrow band.

A proper wideband would give much better numbers.

 

[Bad500Chris]

What tune are you running? Is it the Ford racing tune or a can tune?
usually most of those tunes are tuned to be very safe, IE ~10.9 past redline. The reason, because depending on the conditions of where you are located the air density and quality could be different. So it's made to run safe no matter where you are located.

 

[bull3441]

I would advise against making tuning adjustments based on the OEM O2 sensors. They are typically on accurate in a very narrow band.

A proper wideband would give much better numbers.

11+ use wide band sensors

 

[stkjock]

What tune are you running? .

says VMP in his sig


11.2-11.6 is a good range for a blower car (depends on boost/fuel as to what end of that range is best IMO)

 

[GOTSVT?]

I need to have mine looked at again after my cat issues.

 

[UnleashedBeast]

At Wot my throttle measures 81%

This is normal, but I know how you feel. It's natural for us to think...shouldn't that be 100%? :dw:

:-D

afr at low rpms is in the low 12s. When the rpms get closer to redline it goes into the 10.3-10.5 range.

I don't think the richest chocolate fudge sundae could top that. That is running pig rich, and needs some adjustment. Your target area should be in the mid to high 11.x area. You have some power left on the table in your tune.

and please specify at what rpm @ WOT your car goes lower than 12 AFR. This could be another issue.

I need to have mine looked at again after my cat issues.

Had you been using Amsoil CATS....they would have had "9 lives". I kid....I kid...:-D

 

[GOTSVT?]

bwaaaaahahahahahahaha.
That was clever...... wanker!

 

[NightRide]

Thanks for the input guys, had a feeling something may be off and want to know what to check for myself. It's a 91 oct VMP tune and have know idea how to post the log. I will shoot UnleashedBeast an email and hopefully he can. My car already has a factory wideband and I'm using a log specific for the 2011 but can't tell what the rpms are in each range. I can just see the afr drop considerably as it gets closer to redline.

 

[UnleashedBeast]

You know, for a 91 octane VMP tune....your spark advance looks very aggressive to me. 23.0 to 24.5 degrees of spark advance around and above 6,000 rpm seems a bit steep (RPM is the purple line - Spark Advance is green). IIRC, I only have 21* of spark advance using Torco (~100 octane).

This is your 3rd gear pull.



If I had the conversion formulas that the OEM Wideband sensors used...I would be able to decipher your actually AFR. If it's what I think it is.... (Voltage x 2 + 10) then your air fuel is spot on at 11.63

.815 x 2 = 1.63 + 10 = 11.63 AFR

.815 = the average of both banks

Looking closer at your data logs, I noticed that the widebands remain consistent during your high speed run, from lower RPM all the way to the top. One of your idle logs shows a voltage of 2.00, so that should translate to a AFR of 14.0ish, and that is close to closed loop of 14.7

Does anyone know if the newer aluminum block engines have the ability to be this aggressive at WOT spark?

 

[NightRide]

Maybe that's why she pulls like a freight train up top, lol. So do you think all the runs look ok then?

 

[UnleashedBeast]

Maybe that's why she pulls like a freight train up top, lol. So do you think all the runs look ok then?

Other than the spark being that advanced (on 91 octane), and not accustomed to looking at wideband readings in raw form....I'm still debating this.

I also noticed I never seen your car idle less than ~1200 rpm. Were these cold start idle logs? I'm assuming yes.

 

[NightRide]

Other than the spark being that advanced (on 91 octane), and not accustomed to looking at wideband readings in raw form....I'm still debating this.

I also noticed I never seen your car idle less than ~1200 rpm. Were these cold start idle logs? I'm assuming yes.

Yes, cold start up once she warms up it goes down to around 800. So much for Justins tunes being to conservative.:lol1:

 

[Ray Lucca]

Have you contacted Justin for a review and possible update???

 

[NightRide]

Have you contacted Justin for a review and possible update???

Yes, he said it looks good as is. I must have been doing the conversions wrong. Just want to be safe rather than sorry.

 

[NightRide]

Does anyone know if the newer aluminum block engines have the ability to be this aggressive at WOT spark?

You know I looked back through my logs and at certain points the knock sensors pull about a degree of timing. This may allow the newer cars to run a little harder with the factory knock sensors. Someone with more knowledge on this feel free to chime in.