O2 sensor below tolerance

[Mr Mike]

OK.... So i managed to get my hands on LDR's 3" turbo back exhaust. I welded in the O2 sensor bung and ploped it in. Sounds great. Actually it sounds down right mean!!! and the turbo noise will give a 90 year old a stiffy for a week I'm sure!!!!

The other day I blew a code.... o2 sensor below tolerance, which makes sence because I lost the cat before the sensor. I cleared the code and it hasnt come back since, how ever I expect it to, it only makes sense that it should. So my question is..... how can i prevent the code from comming back with my current exhaust set up, and..... is the computer going to fuel the car correctly now that it has catless exhaust running by the sensor?

just hitting for ideas.....

mikey

 

[chris]

what was the code number?

P0???

 

[katnip]

Mike, I heard your rex today, that thing sounds mean. I was riding my bike with a friend on route 90 this am, almost fell off. Nothing like the sound of a sweet exhaust.

kathy

 

[Mr Mike]

Well the O2 code is

PO420 Cata;ust Effocoemcy Below Threshold (bank1) which makes perfect sence, because I took out one of the cats before the O2 sensor.....

But now.... I ran a tank of regular gas, and since filled with super. today I blew the following......

PO 301, PO303, PO304, and the ever present PO422..... come to a stop at a light, the car idles down then starts missing...... some times under power now.... this just cropped up today. The super has been in the tank for a couple days and the tank was nearly empty when I filled up.

Oh... PO301, 03 and 04 are misfires in clyinders 1, 3 and 4

Could it be missing due to lack of back pressure?? the car had is 90,000 service just 5,000 miles ago and every thing checked out fine, new plugs and what not as well.... I am leaving for New york at 5 am..... hopefully all goes well....

Maybe the ol' girl just needs to breath. I'll be checking mail and this fourm while I am away so let me know what you guys think. and I'll keep you posted.

Thanks for the sound check kathy, I am very pleased with it so far, hopefully I can sort the running problems though

Mikey

 

[chris]

Hopefully the misfires were because you ran regular gas, the computer retarded timing, now its trying to adjust back to super, hopefully. A million things can cause misfires, but the gas octane change is the most obvious right now...or shitty gas. Once when I had my OBS I had multiple misfires from using injector cleaner. I was like WTF and stopped using that stuff.

The p0420 is doing what its suppose to do, you'll need the 'o2 sensor fix"

I do not know what the SUbaru engineers have programmed for a ECU responce to the p0420. On Saturns the ECU runs in normal operating (closed loop) perameters, but sets the CEL on solid. During misfires (CEL on or flashing) the ECU will hunt around for better timing and fuel and if the issue persists it will go into and open loop mode, stealing fuel and timing and resulting in less power, less mpg, and possibly melting cats(if you had one).

 

[Evan]

you can google all those obd2 codes,

or get them here:

http://www.honda-tech.com/zerothread?id=1171263

there is a o2 sensor fix, last i knew it was soldering in a resistor in place of the sensor, but there may be some new and improved method now.

the rear o2 sensor doesn't have anything to do with fuel delivery, it just determines if the cat is working efficiently or not.

 

[Mr Mike]

I didnt have any problems on my drive to boston then to middletown NY, no codes.... it seems that the o2 code (420) only blows when I'm lugging around town, (2,000 rpm) for a long period of time. Since putting useing up 2 more tanks of 97 octane I havnt had misfire problem. So like you said it could have been shitty gas or...... the bottle of injection cleaner i used.. LOL

OK another question.... the car has a "learning computer" I have heard that any time you change things you should disconnect the battery, and power up the car to clear the computer memory. Then let it sit for half an hour or so, reconnect the battery and take it for a brisk drive to let the ecu get fresh readings with your now set up (intake modes, K&N filter, open exhaust). How do you guys feel about this and is it an effective way for the computer to kinda relearn things??

Mike.....

 

[Lawdawg]

Mike,

I am no expert, but I do have some empirical evidence from the group drive that would support. We climbed mount washington, which is a fair change in atmos pressure and temp, especially with a quick climb/descent. On the way down, Runnah's 02 wrx wagon started to spit and sputter badly, smoking and the whole nine. Vinnie, in his infinite wisdom, cooly asked for a wrench and disconnected Runnah's battery, surmising that the change in temp/pressure caused the computer to hiccup. After letting it set for a second, reconnected and things smoothed out nicely 1/4 mile down the road......

 

[Mr Mike]

ahhh ha, that's what I was wondering, I am thinking an ECU dissconnect and a brisk drive may smooth things out for me as well. I have opened up both the intake and exhaust, so i know the car is breathing much better then before. I'll give it a shot and see what happens.....

to bad i'll loose my radio presets LOL

mikey

 

[Evan]

check on nabisco about the ecu learning thing. yes, it does happen, but how you drive it right after you reconnect it will affect a bunch of things, such as gas milage and timing most importantly.

i'm not a big obdII person (yay obdI!)but there are things like fuel multipliers and some 8bit/16bit map thing...

from what i remember if you tool on it right after you reconnect it, your gas milage will suck for a long time because the computer thinks if needs to compensate for constant heavy loads. i'm not sure if going easy when you reconnect it will save on gas but hurt performance though.

i think shiv or one of the other big tuners did the writeup

 

[Mr Mike]

I'll look into it, as much as I would like to have tons of power, in this day and age milage means a lot, i'm getting 24 - 26 mpg right now and am happy with that.

m