josedp

About to pull trigger on a high flow cat and WB o2. Just got the Evo a few months ago so I'm learning a lot. Basically just how to use Accesstuner and scaled my MAF+intake to adjust for near zero trims at cruise & idle.

I am simply trying to find out what a test pipe or HFC affects and WHY (the why is what I haven't been getting an answer on)
In short, I was told on another forum that the cat changes the o2 sensor readings and the car will run lean and you blow up your motor in a spectacular fashion.

This doesn't make sense to me because the o2 sensors are used at idle and cruise, but at WOT the ECU goes into open loop and o2 sensor data isn't used.

I would think (from my limited knowledge so far) that changing something in the exhaust path would change the way the boost builds. Watching for overboost.

So if I install the cat and WBo2, would some tables to start looking at during logs be:
WGDC tables
Target Load Table
to get boost in check before looking at target A/F?

Any advice here? I'm tuning with a cobb AP and Accesstuner Race.

h4ckluserr

I don't know the answer, but I recommend calling a local tuner. Generally speaking they'll be willing to help.

josedp

I may try but I would expect them to ask me to use their services haha. I'll probably just put the test pipe and WBo2 in and monitor what happens and adjust accordingly.

bunnishiwa

You are correct in looking at WGDC and target boost tables.

What happened with my RA is that greater airflow meant boost built quicker than expected, which in turn brought in negative error correction to try to bring it back into line. Some tweaks to not only the WGDC tables but also the target boost tables mean I run with some positive error correction now (which is what I was aiming for).

It can be easier to turn off all positive error correction at first until you've rubbed the negative correction out

Have fun