smp3000

iTrader: (13)

Ok, this is for sure a "dead horse" topic, but I thought I'd share my experience over the last few months....

As most people- I have the full turbo-back exhaust with cat delete. Along with that comes the P0420 CEL unless you buy one of the quick fixes that trick the PCM from seeing that code.

Well I have an OBDII reader and it has the ability to clear the codes. For the past few months i've been clearing it once it pops back up (it usually comes on after a few hundred miles of being cleared) - and I can tell you that the car runs MUCH stronger and smoother when the code is cleared. This isn't just a butt dyno type of feeling- it's a night and day difference.

Has someone ever done a dyno pull back to back with this code on, and then cleared?

Lazeum

iTrader: (2)

I do have the light as well. I haven't felt what you described.
However, I have to get rid of it soon

I've very interested by other comments as well

Noize

iTrader: (24)

I've seen PO420s on the dyno time and again. There is no effect in performance or any fueling or timing change from the back O2.

If you have a tune, maybe its too close to the edge and resetting with better gas is restoring it.

If you're stock with no ECU manipulation, of course you're seeing an improvement, because the car takes a bit to compensate down for the greater airflow.

But your idea is wrong. The PO420 will 100% not effect a tune. There's way too much overwhelming proof otherwise.

smp3000

iTrader: (13)

hmmm- well I have an SAFC-II with Buschur stage 2 settings. Maybe that's it?

I've just been told time and time again that the code won't hurt the performance and I belived that until recently. But now i'm making it a habbit to clear it as soon as it pops back up. I'm tellin ya- I can feel a difference and that's all the proof I need to take a few seconds and clear the code

But do you think the SAFC-II settings may be playing a part in it?

Noize

iTrader: (24)

I don't think they may be playing a part, I think they are DEFINITELY playing a part. You don't have any way to reduce timing, and those setting are too aggressive for most cars with 93 octane.

You need to either back those settings off or just pony up for a cheap reflash. You'll be a lot happier.

boomn29

iTrader: (47)

I had the 420 code on my STi when I was running catless. No performance deterioration at all - and it popped up daily. Some days I cleared if I had my reader, others I didn't cause I'm lazy.

What's funnier, is that I've gotten this got like twice on my '98 Accord! I figure the exhaust is just getting old on it or something. I've cleared it twice in about 10k miles, so it's not often - but weird.

93turbomax

From GM:

A three-way catalytic converter (TWC) controls emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The catalyst within the converter promotes a chemical reaction which oxidizes the HC and the CO that are present in the exhaust gas. This process converts the HC and the CO into water vapor and carbon dioxide (CO2), and reduces the NOx, converting the NOx into nitrogen. The catalytic converter also stores oxygen. The powertrain control module (PCM) monitors this process by using a heated oxygen sensor (HO2S) that is in the exhaust stream after the TWC. This HO2S 2, also referred to as the catalyst monitor sensor, produces an output signal that the PCM uses to calculate the oxygen storage capacity of the catalyst. This indicates the ability of the catalyst to convert the exhaust emissions efficiently. The PCM monitors the efficiency of the catalyst by allowing the catalyst to heat, then wait for a stabilization period while the engine is idling. The PCM then adds and removes fuel while monitoring the HO2S 2. When the catalyst is functioning properly, the HO2S 2 response to the extra fuel is slow compared to the response of the HO2S 1, which is located before the TWC. When the HO2S 2 response is near that of the HO2S 1, the oxygen storage capability and efficiency of the catalyst may be degraded below an acceptable threshold. If the PCM detects the degraded condition, DTC P0420 sets.

If this works the same way as Mitsu then I guess it could effect it.

smp3000

iTrader: (13)

All intersting stuff, but thanks! Makes a lot of sense and I hate that you can't control timing with the SAFC-II but i wasn't in the market to buy anything more at the time.

Some people get a mail-in reflash and then fine tune with the SAFC-II, but since I don't have a wideband or data logger I'd probably be better off selling the SAFC-II (along with the cubby it's mounted in) and just use that money to get a flash.

So you're saying if i get the flash (not from a chick, but from some ugly tuner guy), that the P0420 won't hinder performance anymore when it pops on?

Thanks!!!

MalibuJack

iTrader: (5)

The rear O2 sensor is not used for anything but testing the catalytic converters efficiency.. Thats it.. This has been proven time and again.

What you are experiencing is basically clearing your codes, you also reset all of your trims including octane number.

You should be logging knock from the ECU, I'll bet that your getting enough knock that the octane number is shifting from the high octane map to low octane map hence the feeling of lost power.

The fact that your clearing the CEL light and your resetting the trims is the reason why the car feels different.

Lazeum

iTrader: (2)

Can it be also because by resetting the CEL it resets also the ECU tables adjustment?

I've heard ECU adapts itself to the driving style of the driver (over the last xxx miles) to control fuel efficiency better according to the usage of the car? Do you confirm?

smp3000

iTrader: (13)

Wow, so maybe I back off my SAFC-II settings (or get a reflash) and then somehoe log my knock log. What do I need for that? Just a standard datlogger?

MalibuJack

iTrader: (5)

You can log with Mitsulogger or Evoscan, You can get a Tactrix cable ($95 or so) for logging and reflashing, or an inexpensive VAG-COM USB (must be FTDI chip based though) cable for $20 or so for logging onliy. I ordered one of the FTDI based Cables from HongKong to be sure it worked properly. To be completely honest, your best off spending the extra money and getting the ability to reflash also.. You *WILL* want to go with some sort of reflash after you do a bit of logging. You don't have to remove the S-AFC with a reflash, you will have to clear the settings, tune the reflash (or have someone tune it) then you can use the S-AFC on top of it to fine-tune.. So its not a waste of money.

MalibuJack

iTrader: (5)

There are several problems with OBD-II based scan tools and loggers..

1) Their slow
2) they don't show some critical values needed to determine how well a mitsubishi is running (Octane number, all of the fuel trims, Knock Sum, among others)

smp3000

iTrader: (13)

hmmm ok interesting. So I'd just buy a tactix cable that will plug in where? And then once I do that i'm guessing it will just plug into my laptop and I'll use some software (Mitsulogger) to log the data?