Dyno Tuning with a CAT.

[FordFasteRR]

I just wanted to bring back an old issue that perhaps some of the nubs don't know about ...

It has to do with the issue air/fuel readings with the wideband o2 sensor at the dyno when using a cat.

Here it is: If you dyno your car WITH a cat, your afr reading will not be accurate. The reason for this is because the cat will burn off a lot of the fuel before it reaches the tailpipe, thus, the reading will not be accurate. :eek:

SO what can you do if you have a cat and need to tune your engine?

Simple - install a test-pipe in place of the cat for the dyno session. When done, replace the test -pipe with the cat . You may need to have a shop install flanges on either side of your cat so that you can easily un-bolt it for this purpose.


Good luck ! :phone:

[evan938]

...or just have an o2 bung installed before the cat and use a plug when not dyno'ing.

[FordFasteRR]

...or just have an o2 bung installed before the cat and use a plug when not dyno'ing.

this may work, but the shop would have to be able to seal that plug into the pipe without causing a major disruption in exhaust flow...

[05xd]

Im sure that there is a 18mm cap you could use to seal it off

[Cypher]

there is. just go to pepboys and you can find one. i had one for a bit