Spinmonster

I want to put my cats on my car to quiet things down a bit. They are the FLP's. I have been using my wideband mounted at the tailpipe and want to know what the cats do to the readings. I didnt want to take the headers out for a bung mount at this point. My question is: can I still take the reading from the tailpipe with the cats on?

Innovate lambda meter in case it matters

Thanks.

Bink

Mount it on the inlet of the cat. You'll get more accurate near idle, idle readings - I believe. Maybe some one can jump in and confirm this. I mounted my FJO up there...but then i fried the cats. joel

bomax

iTrader: (3)

I fried my cats too after about 3 months....beware....I too put them on to quiet things down but they just don't last, and are too expensive to continually replace. I would instead opt for installing a long (18") bullet muffler in your I pipe (if you have one).

Gary Z

The following is from the Innovate LM-1 Manual

Spinmonster

First off, I want to thank all of you for answering. You guys are the best. However one piece of criticism and please don't take it the wrong way; it never ceases to amaze me how people will give you a ton of info to avoid answering the asked question.

I have an LM-1 and have the info that came with the unit.
I know readings are affected by the cats.
Tuners on a dyno use a tailpipe mounted wideband.
I didn't want to void the header warranty by putting a bung on them.
I am putting on the cats.

The question is- What do the cats do to the readings? Do the cats preclude taking a reading from the tailpipe of the factory O2 bung after the cats?

bomax

iTrader: (3)

Joel said that the before and after cat reading is the same in another thread (despite what some people say). Try using the search function.

Bink

Nope, sorry, wasn't me that said it.

From what I've read and how I currently understand it:

* At WOT the catalyst's effect on O2 measurements is negligible.

*At part throttle and idle the catalysts do effect the AFR measurement.

*The "pricey" heated, Wideband O2 sensors are able to properly function at a wider temperature range. Therefore at WOT, in an exhaust probe, they output accurate AFR measurements -i.e. as on a dyno.

* The cheaper Wideband O2 sensors require greater (exhaust) heat for proper functioning. Since they operate in a narrower temperature range they need to be closer to combustion - to prevent cooling. After the catalyst may allow for too much cooling and result in inaccurate readings.

I'm not sure which are the "Pricey" and the "Cheaper"??????

I believe it was deezel, jimmy blue and samsz28 that posted most of the sensor info. Maybe they can chime in. Please correct anything I've said above in error.
joel

deezel

I have always heard upstream of the cats is most reliable.
As far as header warranty... can't you put the bung in the transition pipe from the collector to the cat?

Spinmonster

Looks like it is you that should use the search function to get your info right.

Anyway, with FLP's there is no intermediate pipe. I will just put it the test pipes when tuning. The issue was using the meter on other cars and the easiest way to do that is not with a bung mount. Innovate says the readings after the cats are not accurate. So since there wasn't a definitive answer, I took readings, changed to cats and took them again.....not even close.

No problem, I was just looking for anyone with a more definite answer to what I found in my search. Thanks to those who had some positive input.

Bink

Here's a good link on O2 sensors ...alot of good info samz28, 66ImpalaLT1 etc.

https://ls1tech.com/forums/pcm-diagnostics-tuning/155842-help-me-choose-best-wideband-o2-kit.html

joel