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Whats the perfect AFR on a tuned gtr using the cobb datalogs? mine goes 11.5 all the way to the top problem is the black smoke coming out every time i WOT. am i running to rich?
 

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11.5 on Cobb old air/fuel is too rich because it is not really 11.5. Just post your log in the proper topic under engine forum and Ben or Thistle will tell you what you need to do.

Whats the perfect AFR on a tuned gtr using the cobb datalogs? mine goes 11.5 all the way to the top problem is the black smoke coming out every time i WOT. am i running to rich?
 

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black smoke can be a result of a few other things such as:

bad combustion (ignition power not being enough)
wrong cam timings (exhaust opening too soon conbustion ending early)
 

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T1 Race Development
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Yeah, 'a/f old' and 'a/f new' are very different. If you're seeing 11.5 on 'a/f old' then it's much richer than that and will likely smoke black.
 

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JDM R35 Premium
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13-14.5 should be perfect.
 

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JDM R35 Premium
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well 12 and under is way too much back smoke and 16+ is leaning. AFR is 14.4 is ideal but, it's not realistic.
 

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Sophisticated
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Don't most tuners go off the "OLD" afr table and not the new one? I heard the old has more resolution...

Is this true?
 

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just plug in the aem uego and log afr with it. cobb is supporting aem uego so you can get it logged with your AP or ATP logger
 

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T1 Race Development
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I wouldn't trust an AEM Uego reading to tune my lawnmower...
 

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hmm now u got me thinking...

I thought AEM Uego was a accurate tool to check for AFR. What kind of bad experience did you have with it?
 

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They are all over the place. I have two Motec PLM lambda meters, one on each dyno. I use the NTK sensor on both of mine. I've seen AEM's read the same and i've seen them read as much at 1.5 point higher and lower than the PLM. Basically, i've seen them all over the place. Most people don't have two meters on the same car to begin with, much less 1 high quality meter to compare to. It's much easier to just assume the reading you're getting is right but I don't trust an AEM Uego reading in the least.
 

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AFR New is what you want to be looking at.

Cobb re-calibrated their outputs to be much closer to actual wideband readings. The AFR New log will be VERY close to an actual wideband sensor.

The AFR OLD will read a little more than a point leaner then the car is actually running.

So...if you are seeing 11.5 on your AFR OLD log then your actually running between 10.0 & 10.5 AFR

That being said at WOT you want to see between 11.2 & 12.0 depending on fuel...11.5-11.8 is usually money!

Hope this helps...

~Cicio
TopSpeed Motorsports
 

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Whats odd is that my AFR old is matching my Fuel Table (at certain range).. but since the AFR old is supposedly off.. then why is it matching my Fuel Table? and more importantly which AFR values is the ECU using to trim fuel??

My AP is on the latest production firmware
 

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Until a recent AP firmware update (I think it was mentioned in the release notes), AFR new read too rich because a bug was introduced into my formula. Now it is corrected you will see that 12.3 afr old = 11.5 afr new. Then afr new should be pretty close to other widebands.
 

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Until a recent AP firmware update (I think it was mentioned in the release notes), AFR new read too rich because a bug was introduced into my formula. Now it is corrected you will see that 12.3 afr old = 11.5 afr new. Then afr new should be pretty close to other widebands.
I guess that bug is back because I have the latest release and at 12.02 OLD, I am seeing 10.12 NEW.
 
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