A/F too lean. have questions???

[b_dike]

I recently found out that my A/F ratio is 12.5. I bought the car with a 93oct tune, but since MO sucks all I can run is 91oct. Would this be the reason my car leaning out, and if so would adding octane boost help to solve this problem. At least until I can have the car dyno tuned for 91oct.

Also found out that there is 24* of timing in the motor. Surely whoever tuned this car wouldn't purposely run 24* and an A/F over 12 if it was like that with 93oct?

Right now I'm too scared to drive the car knowing what I know now. Any thoughts would be greatly appreciated.

 

[01cobravortech]

How did you verify the 12.5 A/F?

 

[DICobra]

how did you verify the 12.5 a/f?

+1...

 

[b_dike]

Sorry should've said that I had the car dyno'd Saturday. Tech is the one who told me my A/F was in the mid 12's. Anyway I doubt the octane rating on the fuel has anything to do with the A/F but I'm not certain since the fuel is the only change (93 to 91).

I know the A/F needs to be close to 11.7, and I was wondering if a higher octane would have any affect on that at all?

If not, that means the previous owner had the car tuned to run very lean. Which is not cool. Who knows how much abuse it's seen.

 

[01Jes]

24*, 12.5A/F and 91= new motor.

Retune it ASAP.

 

[Anabolic]

i thought 12.5 was rich, if you're getting low 10s you would be lean? where am i misinformed here.. my 93 oct. built block with whipple running 10psi gets 16.0 idle 11.7a/f under load... is THAT normal? or "lean" aswell?

 

[Bdubbs]

i thought 12.5 was rich, if you're getting low 10s you would be lean? where am i misinformed here.. my 93 oct. built block with whipple running 10psi gets 16.0 idle 11.7a/f under load... is THAT normal? or "lean" aswell?

You thought wrong. Idle range should normally be in the mid 14's. The lower the number is richer and higher is leaner.

 

[01cobravortech]

So he verified your A/F with a tail pipe sniffer? That's not 100% accurate. In fact, some readings can be anywhere from .05 - .08 higher than what the A/F actually is. I wouldn't be hitting the panic button. Many cars are running in the 11.8 - 12.0 area. I think it would be a good idea though to get some bungs welded into your midpipe, before the cats and have a shop with a good wideband see what your A/F really is.

 

[Anabolic]

so what would be a safe load range? 12-10?.. the higher number indicating lean cannot be correct. when i swapped my 3.2 pully in. the numbers went down. oposed to my 8psi numbers when i had the 8psi setup.. idle was 16.3 load was 12.3.. went .25" smaller pully ran 15.8-16 idle to 11.7-11.9 load.. i heard 10-12 is safe load for them.. does it make sense?

 

[01cobravortech]

so what would be a safe load range? 12-10?.. the higher number indicating lean cannot be correct. when i swapped my 3.2 pully in. the numbers went down. oposed to my 8psi numbers when i had the 8psi setup.. idle was 16.3 load was 12.3.. went .25" smaller pully ran 15.8-16 idle to 11.7-11.9 load.. i heard 10-12 is safe load for them.. does it make sense?

11.7-11.9 at WOT is very safe. Myself I'm at 11.3 - 11.4 throughout the rpm range. But that's an extremely conservative tune though at nearly 14psi with an unported blower that gets driven hard. You also have to keep in mind that there are a lot of widebands out there that have issues on accuracy.

 

[b_dike]

Thanks guys I think I heard what I needed to hear. DON'T run the car in boost or at WOT, or maybe not at all.

I will tune ASAP...

Also how would you guys feel about this setup with 93oct? 24*, 12.5a/f, 93 oct This still wouldn't be safe would it? Cause this is how I bought the car.:nonono:

 

[Bdubbs]

Thanks guys I think I heard what I needed to hear. DON'T run the car in boost or at WOT, or maybe not at all.

I will tune ASAP...

Also how would you guys feel about this setup with 93oct? 24*, 12.5a/f, 93 oct This still wouldn't be safe would it? Cause this is how I bought the car.:nonono:

I wouldn't feel safe with that one bit!

 

[01Jes]

Thanks guys I think I heard what I needed to hear. DON'T run the car in boost or at WOT, or maybe not at all.

I will tune ASAP...

Also how would you guys feel about this setup with 93oct? 24*, 12.5a/f, 93 oct This still wouldn't be safe would it? Cause this is how I bought the car.:nonono:

21-23* for most on 93 and your A\F is to lean

 

[Anabolic]

11.7-11.9 at WOT is very safe. Myself I'm at 11.3 - 11.4 throughout the rpm range. But that's an extremely conservative tune though at nearly 14psi with an unported blower that gets driven hard. You also have to keep in mind that there are a lot of widebands out there that have issues on accuracy.

well i ended up re setting mine to factory defaults so i can build the tune. not sure who made or ordered the previous tune with the numbers i gave you.. how well placed is the OE tune with 10psi from a whipple? idle is better now at 750-800. not frigan 1100-1150..

the wide band is innovate motorsports. good guage.. i just have to make sur eit's calibrated.. idle is now around 15.2-15.4 at idle.. WOT is 11.5-11.7 with OE tune.. sound good?

 

[01cobravortech]

well i ended up re setting mine to factory defaults so i can build the tune. not sure who made or ordered the previous tune with the numbers i gave you.. how well placed is the OE tune with 10psi from a whipple? idle is better now at 750-800. not frigan 1100-1150..

the wide band is innovate motorsports. good guage.. i just have to make sur eit's calibrated.. idle is now around 15.2-15.4 at idle.. WOT is 11.5-11.7 with OE tune.. sound good?

I strongly encourage you not to go into boost on your Whipple on the oem tune my friend. The oem tune is only set up for the stock pulley boost levels.

 

[Bdubbs]

I strongly encourage you not to go into boost on your Whipple on the oem tune my friend. The oem tune is only set up for the stock pulley boost levels.

+1 get it tuned by a reputable tuner.

 

[nlterminator]

^^^ kaaaaboooom.

 

[b_dike]

Ok in the sct hand held tuner I have the option of adding fuel to the mix at WOT, or at certain rpm ranges. They are increments of 2.

If I were to adjust this would it help and it's 2.0 of what??? Not a tuner here so be easy on me.

 

[Lazerred98cobra]

nlterminator

i would love to see your graph from sas if you have it..

 

[b_dike]

Why would you want to see my graph? I don't have my graph at the moment only because my dad wanted to take them to his work to show off and make copies. lol

You mean the graph that plots hp/tq vs rpm right?

Also I was messing around a bit with the tuner. In the adjustments I changed the 4k-8krpm spark from 0* to -3* and my WOT A/F to 2.0 richer.

Any thoughts thanks