I purchased a 1986 volvo 740 non turbo and it failed smog twice. before first smog, I replaced spark plug wires, spark plugs and air filter, adjusted timing to 12 BTDC, gapped plugs at .030, car failed. Shop stated that catallitic converter was possibly the issue, I then had the cat replaced, car failed again with high HC PPM levels. Any suggestions?
Thank You

 

Make sure the EGR valve (if it has one) and or the O2 sensor are OK.

 

is this a california car? did they replace the o2 sensor when they replaced the cat?

we got 400K miles out of the original cat on our 1987 240 (same engine, same FI), but finally had to replace it a year or so ago. needed a new O2 sensor too (actually, this was the 3rd or 4th O2 sensor in the life of the car).

cheap aftermarket cats suck and don't work for long. if you're in California, supposedly you can't buy the non-CARB approved ones, but the 'good' ones are 2-3X the price so some shops will get out of state converters cheap.

 

It is a California car. O2 sensor was not replaced. I was also considering replacing distributor cap and rotor. I just didn't do that yet because I didn't want to keep putting more money in this car and end up with the same results. I will replace O2 sensor, cap and rotor and take it from there. Thanks for the advise.

 

inspect the cap and rotor, if they aren't badly eroded and fouled with carbon tracks on the inside, then they don't need replacing. with electronic ignition they can be pretty ratty and still work fine, but if there's a buildup of carbon tracks around the inside of the cap between the contacts, and/or the side of the rotor is all eaten away, then less so.

O2 sensor is easy to do and most definitely will improve things if its old. if this was an LH 2.4 car, it would probably throw an OBD code telling you the o2 sensor was bad, but LH2.2 (up to 1988 nonturbo, and 1989 turbo) doesn't have OBD.