My 1988 740GLE non-turbo wagon flunked the emissions test in Dallas, TX. Here are the numbers from my test...

High Speed (25mph) Low Speed (15mph)
1799 RPM 1799 RPM
Standard My Car Standard My Car
HC(PPM): 162 69 PASS 167 84 PASS
CO%: 1.04 0.57 PASS 0.94 0.58 PASS
CO2% 13.4 13.5
O2% 1.8 1.6
NOx(PPM): 1163 1162 PASS 1273 1485 FAIL
DILUTION: >6 14.0 >6 14.1

I passed 12 months ago, and have driven about 12,000 miles since then. I don't know what the readings were last time it passed. The only thing I have had done since then is put on a new rear muffler and tailpipe. The rest of the exhaust system looks okay, but it could stand to be replaced I'm sure.

Does my car have an O2 sensor? Maybe that is the problem?

It runs absolutely great except for one thing. When I get in after a week of not driving it (or even overnight), and the outside air temp is above 90 degrees or so, it doesn't start nice and solid like it does when it is cooler (in fact the colder the better!) It always starts and runs fine, but the start is a little more labored and the rpms rise slowly when it does fire up. I don't know if this is related to anything or not.

I am willing to spend a little to get it legal again. If it gets too crazy, I'll send it to Oklahoma (safety inspection only, no emissions) for a new home.

Any help, advice, and moral encouragement would be greatly appreciated.

BTW, I use Swedish Auto in Carrollton, TX (North Dallas) for anything that is not fairly simple.

Thanks.