Currently helping a scientist (not really) who for some reason allowed his 97 Civic to be tested on the rollers instead of the obd-2 port. Car is a stock EX, has no CEL, and obviously would have passed the port test. It failed the roller (sniffer) test in a pretty impressive fashion. HC and CO are way up, was slightly over on NOx. Aside from adjusting ignition timing, verifying ignition components condition, and changing the oil (its bad), what else should I look for to get those numbers back down?

 

Post the emissions sheet.

Does the CEL work?

There are probably multiple issues, but at the very least the cat is almost surely dead.

 

if i can get my hands on it, i will. was texted to me in the following format:

hc 97lim- 272
Co 54lim- 353
Nox749lim- 924

 

Were O2 levels measured?

CEL definitely works?

 

tune up on ignition?

 

yes, cel works. was not given o2 information

 

If the car has an EGR system, cleaning the EGR valve and passages is important for NOx. Failing all three often means that the catalytic converter is worn out, that may also eventually throw a P0420.

 

He just said no cel...

 

no egr on the ex.

 

Some maintenance tune up work will probably need to be done. fuel injection cleaner should do the trick or pull them out and send them off to be clean and tested. Ignition system can probably need some replacing as well.

 

im going to replace the plugs, swap the working autozone reman dizzy for a known good oe, and retard the ignition timing. retest after those things, will post results. im sure people will question the dizzy swap, but reman units are pure trash. instead of bench testing every component in the POS, i will use one of mine to be sure i have a 100% working unit.

 

No doubt, my cousin autozone crap died on him not too long ago. He ended up having to replace it again...again....again....until finally 1 kept running

 

changed oil, swapped distributors and wires for a set of ngk's, retarded ignition timing significantly. nox nearly cut in half, hc/co both reduced but still way above limit.

 

cat...bad cat..OR you can try a can of CRC guarantee to pass

 

usually high nox is cat, i passed that well under the limit.