DaveP

I know that the test pipe will set the CEL.
My question is, since the O2Sensor will see no catalyst (since it has been removed), what does that do to the mixture while using a Stock ECU?

What power and running issues does this cause?

Do aftermarket ECU's like Mugen or AEM correct for this?

Any other easy work arounds short of programmable engine management?

Finally, anybody know who is still selling test pipes with a sensor bung?

Thanks much.

kitwetzler

zero. the factory ECU based A/F off the primary 02 sensor, it is before the cat. You may see some leaning because of better flow in the exhaust stream, but the MAP sensor should compensate.

DaveP

OK. that makes sense. I had fogotten about the whole control Plus monitor dual sensor set up on the OBDII cars.

Thanks,

DaveP

2000celicaspeed

after i put on my test pipe it seems as though my gas milage went to shit and i am runnign super rich........not sure though i know i lost 5MPG though

BustedShox

I am running a Test pipe also and I was wondering is there anything you can buy or do to make the CEL stay off?

2000celicaspeed

there are O2 simulators you can buy for about 50 bucks....i have one just havent hooked it up yet1

Gernby

I didn't notice any power loss with the test pipe and CEL, but I did notice a significant reduction in fuel economy. I think this is because the ECU runs rich in closed loop trying to heat the catalyst up. I eventually installed an ECG O2 simulator, and that fixed the CEL. BTW, the 3-wire O2 simulators don't work, and the 5-wire units are hard to find.