help. how to pass emmisions?

[T77911S]

my brother has an 87 3.2. the O2 is dissconnected. cat bypass installed, M&K exhaust.
his wrench reset/adjusted the spring tension in the AFM and reset the fuel mixture so it would pass. we checked the O2 yesterday with the LM2. his idle AFR was 23, at 2K RPM it was 14.7. needles to say the car idles like crap. the inspection sheet said the idle O2 was 14.7. why the difference in idle O2?

here are the options we discussed:
1 reconnect/replace O2 sensor and set everything back to original, minus the exhaust, and see if it will pass. adjust mixture if needed just to pass inspection then reset for performance.
2 buy a performance/used AFM and use this one only for inspection
3 reset spring tension and mixture in AFM to make it run better, then set back every year to pass inspetion.

anything else?

[ruf-porsche]

Move to Illinois. All pre OBDII cars are exempt from testing

[gtc]

I don't know how strict your emissions standards are, but here in Washington a good running 3.2 will pass emissions without a cat. When I had my car tested last (although the cat was still in place at the time) the emissions were far below the limit.

Edit: If he still has the factory heat exchangers, why not pick up a used Cat and just swap it out when needed? That's way easier than messing around with the AFM in my opinion, and should cost no more than $150 or so.

[jjrowe]

Seems like at a minimum you need to get that 02 sensor back on. I wouldn't think running that car without one would be very good for it. Thats where I would start and see if that takes care of it. I don't understand how your EFI works properly without an 02 sensor?

Jesse

[john walker's workshop]

too bad you messed with the AFM spring tension.

[T77911S]

the shop changed it so it would pass emissions when he bought it. my guess is he tightened the tension so it would richen up in the mid rpm's and leaned the idle mixture out.

[Peter Zimmermann]

Originally Posted by john walker's workshop

too bad you messed with the AFM spring tension.

Yep. In CA the car would not pass without the cat, O2 sensor hooked up, and everything set to factory spec.

[T77911S]

so is it possible to reconnect the O2 and just reset the mixture just to pass inspection?

[ruf-porsche]

Originally Posted by T77911S

so is it possible to reconnect the O2 and just reset the mixture just to pass inspection?

Anything is possible.

[dipso]

Find another car that looks the same and switch plates for a few hours.

[stlrj]

Originally Posted by T77911S

we checked the O2 yesterday with the LM2. his idle AFR was 23, at 2K RPM it was 14.7. needles to say the car idles like crap. the inspection sheet said the idle O2 was 14.7. why the difference in idle O2?

Air fuel ratio, AFR, is not the same as residual oxygen, 02, expressed as a percent of oxygen present in the exhaust.

If you recall, the air around us contains about 20 percent oxygen and the rest is mostly nitrogen which means that about 4.3 percent 02 was consumed by the engine and only 14.7% (residual) remained in the exhaust.

Cheers,

Joe
74 w/ 86 3.2 conversion

[911st]

I am not an expert but I suspect that with a good O2 hooked up and the car hot, the Lambda circut will self adjust with in a range to achieve the correct A/F.

Also, there is a brown wire under the drivers seat that when plugged into its self reduces emissions for Ca. and Japan.

I would try to reset the idle A/F per factory, hook up the a working 02, and put a Cat on it. Should be worth a try.