It seems some Dyno shop only measures the A/F at the tail pipes. I was wondering if this is 90% acurate or 100% acurate or what?
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How acurate is the A/F when measured at the tail pipes?
- Thread starter Forbidden Snake
- Start date
Its not accurate, and I wouldn't use that dyno shop that does it like that. How accurate it is I don't know, but the probe has a temp range that the gas can be in to be accurate, and it surely isn't at the tailpipe, as the exhaust has cooled to much.
You will also pick up any leaks in your system and your going through the cats which will make your car appear leaner than it is.
You will also pick up any leaks in your system and your going through the cats which will make your car appear leaner than it is.
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So you're saying that measuring at the tail pipes will usually read a bit leaner than measure it before the catalytic converter?
Yes, but how much if any all depends on if you have air leaking into the system (will read lean), and whether or not your converters are hot and up to temp (will do nothing to it cold)
All in all it is just not accurate and I wouldn't pay someone to do it. You'd be better off telling them to get a stephescope (i spelled that wrong i think) and listen for detonation as your a/f numbers are useless.
The best way to tune any vehicle is with actual load (which a dyno jet doesn't provide) and a a/f monitor pre cat close to the header and a set of snap on "ears" to monitor any inaudible detonation.
All in all it is just not accurate and I wouldn't pay someone to do it. You'd be better off telling them to get a stephescope (i spelled that wrong i think) and listen for detonation as your a/f numbers are useless.
The best way to tune any vehicle is with actual load (which a dyno jet doesn't provide) and a a/f monitor pre cat close to the header and a set of snap on "ears" to monitor any inaudible detonation.
Cool... thanks for the help and clarification.
(I'm still learning day by day slowly....)
(I'm still learning day by day slowly....)
So an exhaust leak will make your a/f ratios seem leaner than they really are?
Yes, a lean condition exists when there is excess oxygen in the air, while a rich condition means there is more fuel than there is air to burn it.
So extra air gets sucked in through the leak in the exhaust and causes more oxygen to be read by the o2 sensor? Sorry for all the questions, but I just got my car dynod and it was a little too lean for me (13:1) and I have a exhaust leak. So maybe I wasn't so lean after all.
yes exactly, and your not bugging me asking questions.
Don't discredit the fact that you could be running lean. If you hear any detonation ever you are in trouble. But I would try and fix the leak and go get a WB reading with a weld in bung near the stock sensors.
Don't discredit the fact that you could be running lean. If you hear any detonation ever you are in trouble. But I would try and fix the leak and go get a WB reading with a weld in bung near the stock sensors.
I'm definitely going to go back to the dyno after I fix my exhaust leak and make a few other changes. Thanks for the help.
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