Tom_DB1

At low speed data points to lean missfire with High O2 and HC with Low CO. But you can't hear a stumble. Put CAT in another car no NOx issues. Don't have access to other car any-longer.

Stock chips
New plugs, they look fine after run
Lindsey BE
No vacuum leaks
CAT very hot
Has minor post turbo exhaust leak, this is the next issue to be solved.
O2 sensor is working fine

Data:
Speed 15
RPM 1549
CO2 13.35%
O2% 2.42
HC 128 FAIL
CO% .08
NO 1644 FAIL

Speed 25
RPM 2451
CO2 14.11%
O2% 1.36
HC 36
CO% .02
NO 1217 FAIL

While I expect to solve the HC and get the NOx down, this year the NOx max is lowered from 791 last smog to 689 ppm for 15 mph and 730 for 25 mph. My car has never been below 700 for 15 mph in the last 10 years.

Will using FQS setting of 5 cool off the combustion temps for smog testing?

Any ideas?

Tom M'Guinn

Wow NOx limits just keep going down. Sorry about that. What year is your car? The 86 used to get a slightly higher limit. Have you checked fully for vacuum leaks, and can you confirm that your car is actually going into closed loop mode (narrowband meter, multimeter, by ear when you unglugged the sensor, etc.)? The O2 sensor can be good, but if a vacuum leak is taking it too far away from 14.7, the system may not be able to add back enough fuel to get you back to 14.7. Does the car have any running issues that might point to a bad TPS, injector harness, etc? I wouldn't start flipping the FQS until you get to the bottom of it -- even though the smog limits are too low, your results suggest something is indeed "off" with your state of tune.

PEvans

Tom is suggesting a deeper inquiry than I am qualified to.

For simple-minded ideas, though, try a retest with the low speed in 1st gear. 1500 RPM is brutal. It would at least be instructive to see if you can pass on HC at the low speed but higher RPM.

To make today's NO numbers you will need a well-functioning cat. I don't recall what the limits are, but I don't think you are close at either speed.

I am getting ready to re-smog my '89 with a 4 year old replacement cat, and I do not expect it to pass NO.

Dave W.

Less ignition timing should help bring NOX down.