Failed emissions
 

1985 ROW cooupe failed emissions, CO levels were to high. Will a steve wong chip cause this?

I just went through the same thing. Turned out to be ignition timing and leaks in the intake.

You need to post all the numbers. CO2 is measured, but there is no limit to the amount of CO2 you can blow. Perhaps you meant CO?

You are correct, CO is the culprit. CO Reading=4.40 Limit=1.20

HC Reading=112 Limit=220


CO2=12.17

FWIW ... I had a similar situation. An 85 coupe 140K miles. Stock w/ SW Chip. Would not pass emissions because the CO was to high. The year before using the old chip ( an aftermarket chip that had been in the car for ~ 120K miles) it passed w/ flying colors. I took it to my trusted shop and we worked on adjusting the intake specs using a gas analyzer but could never get it to pass ... and run right. I put the old chip back in, adjusted the mixture to specs and the car passed w/ flying colors.

Steve was very helpful when we were working to adjust the mixture w/ his chip. We just never got it to run right and pass emissions. He let me return the chip without any questions. I am not sure why we couldn't get it to pass emissions. The car started easier, was more fuel efficient and felt like it had more get up and go w/ the SW Chip.

Someday I will do a topend and modify the exhaust. When I do I plan on adding the SW Chip again ... for now I will leave it as it is.

just my $0.02

Is this at idle or on a dyno at speed?

idle

A high CO at idle means the car is running a bit rich. Since the car is a ROW model, it does not have an O2 sensor to sense the rich mixture and adjust it down, so you will have to do it manually by the idle mixture adjustment screw under the air flow meter. It wouldn't matter if the chip is stock or aftermarket, the emissions at idle would measure the same. Also if this car does not have a catalytic converter, all emissions components will be higher by several multiples.

Thanks for the reply, Is this something I can do myself?

sounds silly, but I had the same problem because the previous owner hollowed out my cat. New cat, passed with flying colors. I guess its like saying "is it plugged in?"

Easy to do. If you have access to a CO machine, adjust the idle mixture to between 0.6 and 0.8% by leaning the idle mixture screw turning counterclockwise. If your car has a O2 sensor in the exhaust, you can measure the output voltage to determine the mixture.

This is adjustable via a 3 mm allen wrench up under a plugged hole in the air flow meter. The aluminum plug needs to be removed to access the adjustment screw. Best way to remove it is to drill two small holes in the plug and insert a pair of needle nose pliers into the holes and pull it out. Without complex air/fuel measuring equipment, disconnect your O2 sensor and measure the voltage fluctuation off the sensor with a DVM. Properly calibrated, it should fluctuate evenly between 0.2 to 0.7 volts at normal running temperature. Turn the screw clockwise to richen, counterclockwise to lean. You basically are adjusting the amount of air bypassing the measuring flap in the air flow meter to set the idle mixture. Attached is a pic of the plug location on the meter.

Also, if your car doesn't have a cat, and it still doesn't pass after this adjustment, you need to install a cat.

http://forums.pelicanparts.com/uploads/afmplug.jpg

Here's a typical voltage output of a healthy Bosch sensor:

http://forums.pelicanparts.com/uploa...or voltage.gif

Listen to Steve as he really knows his stuff...

From my experience in passing Nashville's emmissions, your CO level indicates you are running rich (as Steve had mentioned). All you need to do is adjust your AFM as pointed out. I think it would be best if you took it to a shop with the tools to get an accurate CO level instead of guessing. I have buddy that can do for you in Murfreesboro or you can take it to Wicky at Renntag Motorwerks or even Andrew at Musik City PNA.

BTW, I passed emmisions on my 84 3.2 with no cat and a high performance chip from Steve (911 Chips); however, I do have an O2 sensor as it is not a ROW.

Let me know if I can help.

-Darrell

Darrell, if you could foward a number that would be great.


ps. I hate to mess with anything because the car runns great. Will these adjustments alter my performance?

I doubt it - performance should be the same.

My 1989 911 Carrera convertible is chipped and has an aftermarket exhaust with no CAT. I have been taking it to a Porsche specialist who gets it through emmissions every year for @ $200. Any suggestions on ways I can get it through without having to take it to the specialist every year?

Does it have an oxygen sensor in the exhaust? Can I use an oxygen sensor emmulator to pass? To be honest with you since I have taken it to the Porsche specialist every year since I bought it I am not even sure if they plug into the computer or put the sensor in the tailpipe.

Thanks,
Bud

Bud, I think there's a good chance that your tail pipe is still a "virgin"...

Thanks! Does that mean I have to worry about the oxygen sensor in the tailpipe? I have no idea what they did with it when they put on the aftermarket exhaust.

Thanks,
Bud

Steve

Thanks for the great tip on the DVM, I knew there had to be some other way to get a reading on the mixture.