Bought an off-the-shelf Diablo chip from Steeda allegedly burned to accomodate the pulley swap. Other mods are a Steeda intake, NGK plugs, and Flowmasters- the pulley is a 2.93. The A/F ratio looks a little on the high side to me, I've read that it should be under 12 or so. I appreciate your help on this.
Need your opinion on A/F ratio after chip
- Thread starter dkd58
- Start date
12.5 to 1 on the A/F straight across the band. The chip does a great job stabilizing the ratio, just tell them you want it a point richer.
How soon after your install did you dyno? How many driving cycles and to what rpm's did you take it to during those driving cycles?
Next day, 5, 3,000 or so.
Personally, I think your A/F ratio looks great! That is exactly where I would like to be. I have yet to see any definative info backed up with good proof that 12:1 is too lean for our cars Mind you, I am no expert and this is just my opinion.
i think most major tuners shoot for 11.6-11.9. Dont forget to timing plays into the end result also.
I spoke with Nick at Diablo. He stated it was on the high side and offered to adjust the chip at no cost but seemed reluctant. Said it's kind of a hit or miss procedure- recommended I get it tuned on a dyno but I am unaware of a Diablo tuner in the Chicago area. PITA!
The tune is good and steady like it should be, but needs to be a point richer to bring it down to 12:1
Am I understanding this correct? A/F on an 03 should be 12:1. My N/A 01 Cobra is about 13.2:1. I thought they would be about the same. Thanks for the post. Mine will have a tune on the dyno!
SVT 03 Cobra
New Member
where was the A/F taken? in the exhaust i assume... if thats the case it will read leaner than it is by at least 1/2 a point.... I'd say its ok
Yes, in the exhaust.
As I have suspected all along - I finally found some reference as to what a "safe" A/F ratio for our 03 Cobras. I have heard several times 12:1 is lean, and in some cases dangerously lean. But I never could get anyone to back up their statements with definative info on why they claim this. My goal is to run 12:1 across the board and dip into mid 11's at the extreme upper end of the RPM band. I felt this was a good compromise between safety and performance.
Well - I pick up my new copy of MM&FF I got in the mail today, and low and behold on page 90 they are tuning a 03 Cobra at Kenne Bell's shop and adding smaller pulleys and such - they make the statement they were lean with the addition of a CAI and the smaller pulley's so they burned a chip to a "much safer 12.2 - 12.5 :1 from 2,000 50 5,500 rpm, tapering off ever so slightly thereafter." in regards to bringing the A/F ratios to the optimum point. That is and always has been my goal.
Any arguments against this?
Well - I pick up my new copy of MM&FF I got in the mail today, and low and behold on page 90 they are tuning a 03 Cobra at Kenne Bell's shop and adding smaller pulleys and such - they make the statement they were lean with the addition of a CAI and the smaller pulley's so they burned a chip to a "much safer 12.2 - 12.5 :1 from 2,000 50 5,500 rpm, tapering off ever so slightly thereafter." in regards to bringing the A/F ratios to the optimum point. That is and always has been my goal.
Any arguments against this?
I've always figured on anything in the 12's as safe.
If anyone is in doubt, go dig through Rick's threads in his forum.
If anyone is in doubt, go dig through Rick's threads in his forum.
I agree with keeping it in the 12s. Would you not hear pinging if you were running too lean or is that only if you're running REALLY lean?
Well - according to that line of thought - it looks like dkd58 is at the optimum A/F ratio right now. I say congrats and keep it right were it is! :beer:
Here's a question for the group as I never did a stock baseline dyno,... What does a bone-stock '03 show on the dyno as far as A/F ratio? Anyone know firsthand?
This is the email response I received from Diablo through Steeda;
"Looks lean,... the Steeda cold air we have not done on the dyno with a pulley car to look at a/f, but the cold air and cat pipe should not have a great effect on the a/f. The car may just need something a little richer."
I want to thank everyone for their thoughts. There is some difference of opinion but I think that I'm inclined to take what I think is a safer approach, if Diablo thinks it's lean, guess I'll have the chip reprogrammed to add a little fuel. Does anyone see a downside to doing that?
"Looks lean,... the Steeda cold air we have not done on the dyno with a pulley car to look at a/f, but the cold air and cat pipe should not have a great effect on the a/f. The car may just need something a little richer."
I want to thank everyone for their thoughts. There is some difference of opinion but I think that I'm inclined to take what I think is a safer approach, if Diablo thinks it's lean, guess I'll have the chip reprogrammed to add a little fuel. Does anyone see a downside to doing that?
well, you could switch out the stock plugs and as you are doing so look to see the color. If it is slightly white then it is a little lean.
:beer:
:beer:
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