delpa

82 Collector's Edition---47000 mile

NOX 111 pass
HC 321 fail
CO% 4.83 fail
C02 9.5 pass
O2% 3.7 Pass

Any help would be appreciated.
Thank you

Twin_Turbo

How does it run and idle???

It's running rich, check the coolant temp sender in the front of the manifold first, also check it's connection. If it's the old style connector with the round connector replace it with a C4 model with weatherpack connector. Set TPS to 0,525 +/1 0.25V at idle (key on engine off). Also check for exhaust leaks (false lean O2 signal) and check the air check valves on the headers and the switching valves. If the air system does not switch to the cat con in closed loop you will get a false lean signal and it will be running rich.

no_radio

If I recall correctly, low NOX with high HC and CO indicates a poorly functioning or non-functional catalytic converter. You might also check your air pump and your air-fuel mixture (O2 sensor). But I don't know much about cross-fires.
Jeff

BSeery

I would make sure the O2 gage is working correctly, then look at the cat. and also check to see if the AIR pump is putting out any air.

Twin_Turbo

Yes, but the cat con can only take care of so much. If the oxydizing section is bad (receives no oxygen from air system) the CO will be high and if the reducing section is bad it will affect NOx. The cat con will also burn off a little hydrocarbons but if you have too much HC the cat con will get plugged with sooth. So, it might be the oxydizing section of the cat con, if it receives no air.

delpa

Thanks for all your recommendations. I will check

Could a bad spark plug cause this?


[Modified by delpa, 9:37 AM 3/7/2004]

delpa

Could a bad spark plug caused this failure? How do I tell?
Thanks