Well for one those lean burn cars don't use the same cat and are much more tolerant of running lean. So its up to you if you think its fine then use at you own risk. Worst case your cat burns up. Then again why even bother just get a resonated teat pipe it makes more power,smoother power plus all the worries are gone.

 

I would imagine the metal substrate cats would be much happier running lean cruise then the ceramics.

FYI these are the current metal substrates that I know of:

Perrin (150cell?)
COBB (150cell?)
MIL.SPC (100cell)
Apexi JDM ($$$$$$$$$$$$)

Helix makes MS as well but I wouldn't recommend them because of quality concerns. I think there might be some others as well but I only have experience with the above.

 

Going lean of stoich to far will lower EGT's, thus the cat won't light off. The problem isn't "too much heat" it is too little heat actually. Were only going a little lean of stoich, its not such a huge deal. The EGT's are still high enough to light the cat off. Adding EGR will also lower EGT's (less oxygen in the cylinders burning) and this doesen't cause any issues on a stock Evo cat or mitsubishi wouldn't use it.

Cars like the honda civic VX went 17:1 and even leaner while cruising. We are only going mid 15's or low 16's.

If you really want to play semantics running a non heat coated or wrapped downpipe to a cat won't carry as much heat to it allowing it to light off. The stock downpipe is head shielded for this purpose. Subaru puts the cat so close to the engine so that it lights off quicker etc. Also what will hurt the stock cat more than anything is how rich the car runs in open loop stock. Fixing that will extend catalytic converter life way more than running a little lean while cruising will hurt it.

 

Hi John,

What ROM is that?

Looks like 88840013.

Is that right?

 

Its in the top of the picture lol... 88840016

 

Anyone have any negative long term issues with this mod? Has anyone logged their EGTs before and after?

 

Funny you should mention the open loop/closed loop thing. I had mine running open almost always on E85 to get better mileage or whatever, with the cruising cells leaned out- obviously. I've since gone back to closed loop operation, just because my car drives smoother, feels better off starts, and some other reasons. To each his own though.
Since I've gone back to closed loop, for whatever reason, I am now getting better gas mileage- at least 200 to a tank- that's with an autocross weekend.
Interesting, no?

 

Interesting one this...
When I change the Open loops to 45% as per everyone else...
My High Octane map changes by itself in the 160-180 load!
If I change the High Octane map back, the open loops change back to standard.
Have a look at this picture:

 

incorrect definition for your openloop tables...

set them all back to stock..

then fix the defs before starting again

 

This is an EVO 5 ECU by the way.
Not sure how to correct the defs

 

Bringing this thread back!

Is it OK to be in the 16-16.5 AFR range when in cruising, but in vacuum? I'm fine when the boost/vac gauge goes to 0 (15.7). It's very light throttle when this happens. It scared me and I richened the fuel up by .2, it got better, but I had to richen it up another .2. I'm going to test it now, but I don't know how important it is to have a 15.7 afr in vacuum.

Thanks for this mod!!! I'm looking forward to better than 19mpg!

 

I'm still in the 16.0- 16.5 AFR's at cruise in -9 to -2 vacuum. The mod is working, but is this safe? Like I said it looks good when I'm close to no vacuum (15.7 afr).

 

I'm also interested in this mod for my IX. I have a TBE but it came with the car and I'm not 100% sure that cat shield is real or not. I know many weld those in to fool police.

Never having owned a turbo vehicle I don't know if the fuel smell means I'm just rich because it's the stock tune, or there's no cat. I know in the world of mustangs by smell if a cat is there or not. Not so much for the Evo.

What about MIVEC timing and cruise rpm? Are you guys tweaking MIVEC settings when crusing or just afr and timing?

Also is anyone map switching between a 93 performance map and 93 economy map? Care to post them up?

 

search for "Lean misfire limit"

tl;dr- Safe

 

Thanks! Just read your post in https://www.evolutionm.net/forums/ge...ight-load.html