Cale had some interesting observations about his A/F ratio while on the dyno on Sat. Here's what he posted in the events forum. I thought I'd bring it over here since it's a tech Q.
\"Did anyone else run the dyno with an in-car wide band unit?? reason i ask is because my tech edge wide band 02 that i THOUGHT was correct..was way out from what this dynos A/F readings were...
I tried to richen up my low range mixture for the drive home..and the car ran like crap and started stalling on me..and my wide band said i was at 10:1...wich makes me think that the unit they had in my car was not getting a proper reading..i dont think i possibly could have been 18:1 A/R
LOL if i was at 18:1 good think i did not get a chance to try a 20PSI pull
thanks again..that was a good time!
Cale \"
When I was looking at Brian's and Fred's results I was very curious about how the probe was installed in the tail pipes. Cale's observations proved what I suspected was happening. Our tail pipes are usually so short that the probes they use don't insert very far. Add to that, a lot of guys like to have a ricey 3\" tail pipe. What happens is that during exhaust pulses, outside air will be drawn in the tail pipe. This outside air dilutes the reading the exhaust analyzer gives out. There's no way Cale's engine could be operating at boost with an 18:1 A/F ratio. It would have pinged so bad everyone would have heard it.
Cale, go back to the carb settings you had with the readings from your wide band O2 sensor. Those will be correct.
I have this problem every time I go into Aircare. If they don't add a rubber extension tube on my tail pipes, the oxygen dilution is so bad the analyzer won't allow the cycle to even start.
