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93 EJ22T failed high CO
HCs okay, thinking it's the 02 sensor getting lazy

Parts houses say EJ22 can use a universal three wire but
the turbo can not.

I am questioning this as the difference is about 40 GW's

Any comments appreciated

my comment:

Search.

thanks sleeper, I did... many different search criteria

maybe I missed the one that answers my question

here is the closest I got but I don't see the answer

kam wrote:
Generally speaking, there are two types - zirconia and titanium (not to mention the more exotic ones on more recent vehicles). You need a zirconia type which changes it's voltage when subjected to different mixtures where the titanium changes its resistance. You can use pretty much any number of wires like Z1 says - just get the signal wire right. You will see a gold contact on the connector of the Subaru item. This is the signal connection so verify what wire it is since they do tend to use O2 sensors with wierd color conventions.

I see nothing in the FSM that would indicate the turbo and n/a's have different reacting O2 sensors.

Regardless, I highly doubt an O2 sensor is going to cause you to fail. You're only in closed loop at cruise, and possibly idle. Is yours AWD or FWD. If it's AWD, and it's not on a dyno, it shouldn't have any load on the engine, and should pass.

You've got another issue somewhere. Possibly bad cats..... CO is caused by incomplete combustion or low combustion temps. Did you drive around at all before getting it tested? Stick some seafoam in, and give it an italian tune up.

thanks Josh,
I am at the mercy of the IM inspector here.
He made reference to the HCs being controlled by the ECU and the cat.
The CO a direct function of the 02 sensor and the ECU.

Yes the car was driven pretty hard before the test but still had to go through the PA
"Cat heat up" part of the IM test (only needed when the test apparatus thinks the car is in open loop.)
Giving more credence to the lazy 02 sensor theory so he says.

I have no service history on the 02 sensor - this car was recently purchased from out of state.

PA does not use a rolling test it only uses a stationary 2500 RPM for 30 second test
coupled with a 30 second idle test. (It passed the idle test, both CO and HCs)

How close to the levels was it on the idle test?

I still say put some seafoam in and give her a good drive. I suppose if that still doesn't work, pour some alcohol in the tank.....needs to be the high percentage stuff though.

The reading at idle were close
but passable

I'll give the Seafoam and some of the "Guaranteed to Pass"
stuff a shot

The IM machine is online with the PA DMV during the test.
I do not know how many shots at passing I get.

After failing , I do know I have to fill out a form stating what I did
to get passing concentrations.

A new 02 sensor sounds better than "added a can of Seafoam"
I'll tell them I fixed the wiring to the sensor if it works.


Thanks again Josh (I'm working on getting a picture of the HVAC plug we spoke of..BTW)

I still would like to replace the 02 sensor as to establish a base line for future changing.

Skip wrote: After failing , I do know I have to fill out a form stating what I did
to get passing concentrations.

Hmm, I live in PA also, and the first time I put my '91 Turbo through, it failed idle, but passed 2500. I put some Seafoam through, and it passed after that. I never had to fill out a form like that though.

After handing my key back, the guy did ask what I did to get it to pass.

It is very possible the IM inspector must fill out the form for the DMV
thus his question to you.


I connected an air fuel ratio meter to the 02 sensor and grounded the sensor case (in case the threads / exhaust system ground may be creating resistance.

Being aware these simple A/F meters are basically an on off indicator and not a true measure of the mixture such as a wide band unit is,
after warm up and driving the vehicle moderately hard, (8psi on the boost gauge) the meter never registered above a very lean condition.
I also tried my Fluke series 77 DMM. (0.01 ~ 0.02 vDC was it's reading)

After the drive at idle, the exhaust smelled somewhat rich but did not reak like my Webered no cat Brat does.

My contention now is the 02 sensor output is low causing the ECU to think the engine is running lean.

It therefore compensates by increasing the pulse width of the injectors causing the high CO and HCs.

The HCs being dealt with in the cats the CO
(possibly a by product of the excess HC being burned in the cats)
getting me in a fail position.

All comments greatly appreciated.

Your theory about the HC's in the cat is possible I think.

Do you have access to a laptop? If so, try out Vikash's scan tool. It'll give you fuel trim info as well as O2 sensor data.

The O2 sensor value should be oscilatting back and forth under normal cruise. Under acceleration it will read rich.

Josh,
Yes I have several laptops (no desktops though)
I did a search for Vikash's scan tool and saw many refs to it
but no link to it.
I would like to build it and give it a try.


Your description of the A/F reading is exactly what I have seen
using this type A/F meter.on my other turbo'd cars.

http://bbs.legacycentral.org/viewtopic.php?t=16219
http://www.graphics.cornell.edu/~v/bcbfscan/

Thanks again Josh and Vikash
I will give this a shot and let you know how it goes

I decided to change the 02 sensor to a new Bosch
single wire 02 sensor I had in my inventory

I wired it to the signal wire and left the heater wires unconnected.

I went for a drive and the A/F meter responded as it should.

Maybe not as quick as it would with the heater but
I felt confident enough to try the IM test again.

How do you say "Flying Colors"
thanks again for the repiies
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Damn.....that's a pretty substantial decrease just with the O2 sensor.

I was going to add some Seafoam but the can I "thought"
I had was empty.

After the A/F meter started acting normaly I figured
I'd go for it.

BTW @ 218 kmi the old 02 sensor wiring still had the factory black
corrigated plastic wrap on it - with the end seals intact.
So it is possible that it was the original unit??
Atleast replaced with a factory unit .
I do not know if the OEM units have the plastic cover?

Having read this several times, I continue to be confused.

I too failed E test and CEL said O2, knock and MAF. Replaced O2 sensor with NGK universal fit (two white and one black wire) per NGK tech support advise. Car runs like bag of sh... Went for drive, same thing. Disconnected said sensor, and car runs great!

E-test says: CO 0.00 at idle and 0.00 at 2500 RPM. HC 17 and 77.
CEL cleared by itself and has not come on again after 100km. With Old sensor; CO was 3.9 and 3.9, and HC 135 and 295 ppm.

Now what? Do I get a Bosch single wire (it's cold in Canada!)? Part number? Availability? Do I connect it to the black wire?

Thanks,

Phil
Newbie to Subie.