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PorscheGAL PorscheGAL is offline
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Join Date: Dec 2008
Location: Central SC
Posts: 1,912
Why to monitor your AFR!


When I added my LM-1, I felt it was more an item of curiosity than a critical item. I have since changed my mind. Look at the two session below. They were taken on the same drive and 1 hour apart. The first shows my AFR at 13ish while cruising and just around 10 on boost. This is how most of my drives are.

The second session shows a dangerously high AFR and how these cars change. I watched my AFR creep from 13.2 to 14.2 while cruising after an hour. This was odd to me, so I decided to record it a short session for record. I'm glad I did. I couldn't watch my gauge, but the recording shows that my car was in a range that could have caused damage.

Fortunately, my LM-1 keep me aware of the changes and I drove cautiously home. I have now learned that my car, after extended drives, leans out and loses its ability to maintain a predictable AFR.

My next project is an adjustable WUR to see if I can fix this problem. Also, I now log boost and RPM.

My minions:'86 911 Targa 3.4, '87 930, '05 Lotus Elise,
'19 Audi RS3, '13 Focus ST, '16 Focus RS
Old 09-13-2010, 05:56 PM
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