Quote:
Originally Posted by san rensho
Jager- I thought the O2 voltage before the cat was supposed to be a sine wave and the voltage behind the cat was close to a straight line.
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I'll answer because this helpful Thread is linked in an another Active SAI problem solving Thread.
Yes , the O2 V ahead of the Cats should be a sine wave
but only after the SAI Pump has stopped (90 seconds max on a cold start)
The effect of a correctly functioning SAI system is to pump in so much extra air(O2) before the Cat ,that the excess HC is burned off. This temporarily smooths the sine wave.
The problem is to see this on Durametric. You need a fast laptop on 110v power to be fast enough to connect and see the graphs for both banks simultaneously - look for Voltage ahead of Cat.
If the diagnostic tool is active before the cold start, you will see the sine wave momentarily before the air from the SAI pump reaches the exhaust. I can't figure out how to do this with Durametric but it would be a useful diagnostic technique if someone else can explain how to do it.
I am not an expert on this so please correct if necessary for accuracy.