AFR Readings

[jcslocum 93]

I have Vivian on the road now and running pretty good. I have installed a wide band 02 sensor and have an Innovate LM2 for reading and recording.  This is the first recording of a few full throttle pulls in 4th gear. I had an issue with the RPM readings on this drive but will remedy that for future tests. 

 

It looks a bit lean to me running in the upper 14's and close to 15:1 AFR. What should a full throttle AFR be for a turbo engine??

 

Between the 2 blue arrows is a bit of 3rd gear. Blue to red is the 4th gear WOT pull to just above 6000 RPM.

 

The black line is for reference at 15:1 AFR

The software is Logworks that Innovate uses to view and the hand held LM2 does the recording. 

This is the kind of RPM track I'm used to seeing on my '66 porsche:

 

Edited April 25, 2017 by jcslocum

[Vulcan Grey 235 1 Vehicles]

14: or 15:1 would be super lean on a turbo...

The stock Lotus SE code tries to get as low as ~9:1 in 1st gear, 10:1 in 2nd, 11:1 in 3rd...  I've see approx the same with my PLX wideband AFR mounted after the cat.

 

Where are you measuring? right after the turbo, after the cat?

How are you getting the RPM signal?

[jcslocum 93]

Travis, thanks for getting g in on this!  I'm measuring the AFR about 20 inches after the turbo. It's an 84 with no cat and no other emissions controls installed. These are new carbs that have never been on this car and built to the euro/row spec. I think the mains are 160's and need to be bigger. 

 

Im getting the tack signal right off the coil with alligator clips. I have just gotten the inductive clamp from Innovate so I think that will fix this issue. 

[sailorbob 178]

A WOT AFR of 11:1 is fine at the higher rpm ranges ramping in from 13:1 to 12:1 at lower rpm ranges. If you are at WOT at high rpm for extended periods of time then increasing the AFR can help with lowering the EGT.