Can an O2 sensor be connected to a Gray Market DME?
 

I recently brought my car in to have it smogged (had a Steve Wong chip with a Dansk bypass pipe).

My wife was rushing me to get it done since we just got back from vacation, and it "expired in a day". Feeling the pressure, I thought I would give it a shot, however, the car was high in all areas HC, CO, and NO.

I called up Steve Wong for assistance (he is a fountain of knowledge), and he advised that I take the chip out and place back on the catalytic. Additionally, he suggested that I set the DME to the 3rd click (clockwise) to lean out the mixture.

I did all of the above, but it leaned it out way too much, and the HC and the CO readings were almost non-existent (actually zero for the CO). But, the car failed again, since the NO levels were still too high.

Steve recommended me to just place it back to the stock "zero" position on the DME, and then have it measured before I run the California state test again.

My question is can an O2 sensor be integrated into a gray market DME box to make it actually use the sensor the way it was meant to? My car was federalized, but the car has the little "black box" that sits next to the DME for "show" - it is actually not connected to the DME at all.

Thanks!!

Bump. Anyone?

Look on the left side of the engine bay toward the back. If there is a lead laying around that will be the connector. You will still need to weld a bunghole (heh heh, bunghole) onto the exhaust piping so that it is prior to the cat and detecting exhaust. The silver BAR sticker inside the driver door SHOULD tell you if you need an 02 sensor or not. If you have the lead in the bay it would not hurt to have one....

Best to do your DME tweaking with the engine running and connected to a friendly P-car shop's gas tester. I went out and bought an obsolete one that still works but is not compliant with OBDII. So an 18,000 dollar machine is sold to me for 200....

When taking it to the smog tester, make sure it is good and hot. Leave it idling if you have too. Cold, air cooled engines will fail, ask me how I know.

If you are still high on HC or CO you might be able to sneak by, by disconnecting one injector and having it work as a "air pump"......it will dilute the exhaust stream. Just don't let the smog tech see ya do it...

I have done a lot of testing on my 3.6 and found this out the hard way.

Good luck, PM me for any other questions.

Thanks for the reply Mike.

I already have the hole in my Catalytic with an O2 sensor in it, it's just that it goes into a small black box under the drivers seat to fool the EPA guys that it was actually connected - which it isn't.

Someone else told me about the 5 cylinder deal, I just find that a little hard to buy - wouldn't the car run poorly (as you can tell, I have never tried that).

I am trying to get the exisitng O2 sensor I have someone hardwired ino the DME itself.

Disconecting the injector....It doesn't run great...but it runs...it DOES lower the HC and CO....confirmed it on the analyzer.

I've done this one in the past but never on a Porsche so if this is bad advice someone chime in quick please. Suggested by my mechanic friend.

After a full tune up, (may not be neccesary but I did it anyway),
run the tank as low as possible.

(Leave only as much gas you need to get to the inspection station, finish the test and back to the nearest gas station.)

Dump a couple of cans of dry gas into it. The stuff is mostly alcohol, and as we all know alcohol burns really clean.

My Mitsu failed one day, tried this and the readings were almost 0 across the board.

Scott

You have a number of problems:

1. You should re-install the stock chip.
2. If your DME is really a Euro one (as it sounds like - 051),
the EPROM & circuit board does not utilize the O2 sensor.
That's why the little mickey mouse box. The DME & EPROM
must be modified for "real" O2 operation. You just can't bring
it "into" (hookup to) the DME.
3. You must re-install the CAT, especially with the Euro
advance timing, because of the NOx to pass emissions tests
and the visual. This becomes even worse with performance
chips.

Do a search on performance chips and emissions tests, to obtain more
info about your problems. Also, check out this web site (www.systemsc.com)
on the Graphs page and the Problems page for additional info the
emissions.

Loren, I put the car back to 100% stock by putting back on the Catalytic and the stock chip the other day. I did notice that the little black box does connect into the DME, and seems to help regulate the voltage that I am seeing on the O2 sensor.

Right now I am getting about .5V DC to .825V DC when I push it to 4-6K RPM. When I had my last conversation with Steve, he indicated that I need to keep these numbers between .1V to .7V to be in the right range to pass smog.

Do you think it would help if I turned the FQS to the # 4 position to retard the timing -2.79°?

Thank you for replying - I think both yourself and Steve offer up quite a bit of useful information.

Retarding the timing using the internal switch will reduce the NOx.

You can check the function of the O2 sensor thru the DME by
grounding the O2 input to the black box. This should result in the
mixture becoming rich and the idle becoming lower. The usual
approach used by the black box is to vary the air flow meter
input to the DME based on the O2 sensor voltage, which will
affect the mixture.

If the CAT is still O.K., you should be able to pass the emissions
test with all your fixes. Good luck.

Do you have the static 2500rpm test or the rollers?

Sorry Mikez, but I don't have a roller at home, but I did drive around last night with my voltmeter hooked up the way Loren describes it.

I was planning on asking them to do a dry run without reporting the results to the CA DMV. I have already dropped $60 for the first failed test, and $25 for the 2nd failed test. The guy was nice enough at the shop to allow me to do one more retest at the $25 price, so I will try what Loren says and retard the timing by placing the FQS to click # 4.

Thanks!

When I meant roller test...I meant, does the area that you live in require one? Some Counties in CA require the more stringent loaded test, where your wheels are on a roller and you are tested at 2500 rpms while the rear wheels are moving on the roller.

In the rurall areas, a static 2500 rpm test is required.

Oh!!! :)

Yes, they do require a roller test - those bastards!!!

Well, I just tried out positions # 4, 5, and 6 on the FQS, and it looks like position # 6 is the winner (6 = +6.3% fuel, -2.79° timing). With the volt meter, I read between 2.0V DC to no more than about 7.0V DC all throughout the throttle range.

One last question: Does the catalytic also filter out NO? I thought it olny burned off excess HC and CO.

Most CAts are TWC (three way CATs) which means CO, HC, & NOx.

What a pain this is! I just called around, and none of the 3 places I called do inexpensive dry runs any longer. They all want to charge me $59 to $95, just to run the test on the SAME machine that they use to report to the state. According to one really nice person at German Motor Works here in San Carlos, they said that their old gas analyzers' don't even check for "NO" - that is a new thing, and the way they are catching gross poluters.

I guess I am just going to have to rely on the results that I am getting from the O2 sensor. Unless someone in the Bay Area happens to have an NO tester that I can use?

Most good shops should have a 5 gas analyzer with NOx. You need to call around
some more. I just noticed that the CO reading posted is 6%, not good. It should
be less than 1% after the CAT. Make sure that it's really not 6% or you'll fail.
There is a timing setting where it doesn't affect the CO. Select this setting.