[T3] lean exhaust

[Daniel Nohejl]

It would seem that there is no normal as no one seems to know where VW hid the AFR/CO2 numbers. A retired VW FI tech from another forum swears by 13.2 at idle but I don’t think he ever found the document that says that. In any case, there’s a lot of dispute around AFR numbers in the absence of factory specs and readings can be strongly affected by where the probe is placed. Is yours permanently placed or is it stuck into the tailpipe temporarily? I’m guessing that if you only have an idle reading, you might be using the temporary tailpipe style. 

If you’re in an accurate spot, your 15.1:1 is too lean. From a D-jet manual I found a '71 should have a CO% of .7 which translates to an AFR of 14.21. 

I have a ’69 “B” version of the FI and if I was too lean at idle, I was waaaayyy too lean above idle. However, you have a more adjustable MPS and might want to look at The Samba for guidance about adjustment procedures and tools for adjusting the inner and outer parts. 

There will probably be some disagreement around this. 

Daniel



> On May 5, 2017, at 7:44 PM, KENNETH ROGERS <kensue356 at cableone.net> wrote:
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> 
> Question. Does FI vw's type 3's run leaner than carbs in vw's Type 3's? On carbs, it is 14 to 1 lean air to fuel ratio. My 71 FI is getting 15.1 to 1 lean air to fuel ratio at idle. While accelerating it goes all the way off the scale super lean, then deceleration it goes back to 15.1 to 1. 
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> Is this ok or normal? 
> 
> Ken 
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