Ok two things have happened recently, in the last three weeks..

#1. My idle will very quickly jump from 14.7 to 13.9 and hang there indefinatly.

#2. Ive had to lean out my fuel map a few times in the midrange because it kept trending richer and richer.

#3. Cruising in closed loop ive seen my a/f hover around 13.5-13.9. Then out of nowhere it will jump back to stoich.


At first I thought maybe it was a tuning issue so i tried different injector sizes.. trying different latency numbers. But in the end I just put everything back the way it was originally tuned because thats what had worked all along. None of my changes made a difference besides putting the car out of tune. but cruising and idling still had same probem. I also reset my ECU and the problem stayed exactly the same afterwards.

So Im thinking vacuem leak? I just went out and bought all types of new clamps and im going to be buttoning down everything i can in there. I also made an app't. to have a real mechanic check it out and do the test, with a smoke machine, because i dont have a air compressor. but they pushed me out to next week.

what would you do?

I just pulled this code..

PO136 - 02 sensor circut malfunction (Bank1 Sensor 2)

Sensor 2? front or rear? I have some antifoulers/fix in rear if that matters

edit: OK i so i searched and found its the rear sensor. I checked my i/m monitors and everything says not ready that has to do with the rear sensor..

Should I

1. Remove one of the two anti-foulers and reinstall closer to exhuast stream?

2. Remove the mechanical fix all together and get a P0420?

3. Replace sensor?

4. Douse car in gasoline and throw a Zippo at it?

ordered sensor from NAPA - 7-10 day wait and $140 for that POS Bosch. The price for the front sensor is $180!! I think part # was 15025, there is a difference between manual and AT cars but its the same sensor for different year 2.0l MT cars from what i saw in the book.

In the meantime Im going to remove the mechanical fix (anti-foulers) to see if the sensor is really broken or if the anti-foulers are causing this somehow. I would have expected a p0139 instead p0136 of the anti-foulers were an issue.. but Ill find out I guess.

i would like to take this time and thank myself for helping out myself..and the woman at NAPA with the awesome tattoo. :)

If your rear O2 is not reading out a bounce between lean/rich as you idle and cruise and instead reading a near constant lean, it will cause the car to idle or cruise rich like that. This excludes decel fuel cut. Even if you have disabled P0420, etc. by reflash and get no CELs this can happen.

You can log your rear O2 signal and see if it is bouncing. It doesn't need to be at a particular speed or duty, as long as it is bouncing alittle between.

You shouldn't need the antifoulers if you can flash out the CELs.

You could have an exhaust leak between the front O2 and the rear O2, allowing air to enter, making the rear O2 read leaner than it should.

i havnt yet messed with a tatrix cable or any of that stuff yet, although its aparent i need to. however if there is a real issue with the sensor wiring or the sensor itself getting rid of the code wouldnt help. actually.. im glad the code is thrown so i have an idea whats wrong

ill check for an exhuast leak. maybe there is a small leak coupled with the antifoulers are causing the code. however this code seems to indicate a wiring issue or bad sensor. i could have damaged the wires during the install.. maybe twisted them loose i dunno.

thanks
Paul

ok uninstalled anti-foulers/420 fix, installed new clamps on every vacuem hose and connection i could find last night. reset computer. problem is the same.

It seems to target 13.7:1 I cruised to work today solid at 13.7:1. Is it possible that my tuna is borked? Im going to calibrate it tonight.. I dunno. at WOT the ratios seem normal though. But now i have this bug in my ear about it reading wrong so i have to calibrate it again just to be sure. before i start doing additional work trying to figure this out i want to know for sure.

I cleared my codes, if I throw a P0420 then my sensor is working, if I dont .. ill probably throw a p0136 and the emissions will say not ready indefinatly. until new sensor is installed then.

Hmm. Well if it was wiring, you'd probably get a different CEL, IMHO. There are other CELs for if the wiring is shorted or open. For all sensors, there are generally at least three CELs. Short and open for every 'loop' (heater, signal, etc), and one or more for various "performance" issues. P0420 is just a performance issue and that alone doesn't indicate a wiring issue. It's still possible, but I think less likely.

I'd still guess leak or bad sensor. Logging the ECU with rear O2 signal, front O2 lambda, and fuel trims would help a bunch. You can do that with a laptop and pretty much and OBD-2 cable (borrow a friend's APv1 cable, etc.)

Dude,

If you need OEM subaru parts call up TheKingofParts.com

They are a suby dealership. **** i think my buddy paid $90 for a front o2.

^ Thanks alot man!! Because NAPA just called me back today and said that Bosch sensors were on national backorder :(

where should i buy a cable and download software to use for logging the rear 02 signal or fuel trims? is there a tatrix.com website.. i can search it out actually.

thanks

paul


edit: ordered the part from them should have it next week. that was easy. i just hope it fixes my problem.

bringing this one back...

did you find a solution? i seem to be having a problem similar to this. when i'm at idle, the afr will dip to 13.7-13.9 for about 10-15 seconds then come back up to 14.6-14.9 and stay there...
also, when i'm cruising and let of the gas and get back on it, it'll dip like it does at idle...
should i even worry about this?

damn it I have the exact same prob as you Chino. I know I definaltly have a leak between my shorty downpipe and high flow cat. So that woud definatly make the rear o2 read lean. Hopefully a new gasket will fix it this prob.

that's an interesting thought...i did notice that i've developed a very small leak around the donut gasket. i dont think it's big enough to cause that problem though...i was thinking that me being catless had something to do with it...

let me know if the gasket fixes your problem.

Yeah I'll definately let you know, but I'm pretty busy at work, probably won't get to it until most likely next weekend.

Any solutions?