Downpipe elbow question??

[jetjock]

....I agree with that, but never understood why they were able to do so. I know the cats affect the way post-cat oxygen sensors respond, but didn't know how that could affect tuning the car using exhaust tip sampling....

Since lambda is basically transparent though the catalyst the sensor will just read a tiny bit leaner. Otherwise it's not a big deal. Remember, all these things do is measure O2. It can't be used to control fueling when post-cat though. Otherwise, I agree it needs to be up front.

 

[toyotanos]

Very interesting, I would have figured the overall sensed ratio would have been majorly messed up by the catyalyst's ability to store and release oxygen, or at least more than that.

Might explain why my tuner was OK with tuning E-85 cars to 12.5:1, rather the more traditional 11.5:1, but maybe not. He did stick to 11:1 on pump, might be something else. Thanks, Jetjock!

 

[mstgeer]

checked the car today and the down pipe has a bubble in it, i thought it was a cat but nope just a bubble lie an expansion chamber and theres a pre welded bung 18 inches down the pipe again i just bought this car so not certain whats going on with it

That is a pick of the old style Tanabe downpipe. If it is the same as the new ones like I have, the bung is for an egt probe and will be too small to fit O2.