I just fail a smog check in California, my 97 850 has about 300,000 miles on it. It runs great with no check engine light. I did get a code a few moths ago for evap system. Will that effect NO levels? My levels where 506 the max is 424, After decarbonizing it went down to 496. Cat was replaced a few years ago. Any suggestions, should i decarbonize again?

 

high NOxs usually points to running lean - so you may want to check the oxygen sensor resistance, check for minor air leaks in the intake (and around the injector seals) and check for exhaust leaks. Since you are close to spec (49 state legal?? ) you may not be out of range enough to throw a code but enough to run up the measurements. Also check your plugs for temp range and gap. An old school trick was to reset the timing to trade off NOs for HCs but I don't thing you get that option anymore...

 

Will just got a PO442 code from check engine light that just came up, but that is the evap system. My car has run a little above center on the themp gauge for awhile I don't know if thats an indicator of anything. I changed the plugs and wires last year but I'll check those again. BTW during the test I did notice the car was ticking pinging while trying to maintain 15mph, is that do to the car running lean?

thnxs

3s0x

 

Yes, pinging (or pinking) is a good sign of running lean or timing that is too far advanced. things that can cause running lean include components like temp sensor, air pressure sensor (I forget if the 850 non-turbo has one), O2 sensors (850Ts have two, again not sure about the non-turbo), injectors (if your car seems to have full power and runs smoothly not likely) and air leaks on intake and exhaust. I'd start by inspecting all the 1/4 inch vacuum lines and T connectors, and the air boot for signs of cracking. next I'd lightly spray some engine starter spray around the boot and injectors and vacuum lines to see if any gets sucked in with the engine running (it'll bump the idle speed if you find something). I'm betting you have a cracked vacuum line or T... :-)

 

I just tested all the vacuum hoses and they seem fine but i did hear a hiss from a valve right next to the fuel filter. Any idea what that is, roll over valve maybe?

 

you are talking about an 850 here right - where the fuel filter is under the car near the rear tire? I'd need to look but I doubt it has nothing to do with a lean burn. some FI cars use a constant pressure fuel delivery system where fuel gets returned to the tank and the entire system is under pressure (ie why leaving the gas cap off on some cars will throw a code). Its not uncommon for the fuel pumps to buzz too (the 850s have the pump inside the tank but others like Audi 4Ks had external pumps that could make a racket... I can give a listen to my 850 today (gonna be 80 here!)