Failed on my idle readings, (car runs at around 600-700rpms) the hc ppm reading was 416 when standard in nj is 220.... has new cat, fairly new flowmaster cat back... its a 305 tbi, what could i do to drop the hc ppm

 

Change the oil & filter, check that the distributor base timing is at 0* BTDC. And make sure that the engine is up to temperature and in closed loop during testing.

With the HC that high it may be that the engine is mis-firing. So check the plugs, wires, cap & rotor.

RBob.

 

do exactly what Rbob said, before any testing done by the state on my RS i always do a FULL tune up with fluid changes, and then run a tank of gas through the car with some treatment, then fill her back up, drive her around for a few minutes, then take her to the test, i have not failed yet

 

fresh oi,l new gas, new oxygen sensor, new cat hc ppm at idle keeps going up......

 

perform a tuneup. put the stock style and heat range into the engine. I use AC DELCO plugs on all chevys. and dont put a fancy plug just a stock sytyle delco plug

 

U need a fresh cap and rotor, wires and use either AC delco or bosch platinum plugs(just the regular single platinum no +2 or 3 or all that) i bought my car and it still had the stock ignition even all 8 plugs were original, replaced them with bosch platinums and everything was great, then a friend convinced me that delco's are the only good plugs for thirdgens, like an idiot i went out and got new delco's after on using the plats for 3,000 miles, and believe it or not i was happier with the preformance of the platinums over the delco's,

dont forget about your timing either, you really have to do a full blown tune up, before tests or atleast every other test

 

she has a full tune up also, plugs wires rotor cap.....

 

hmm and your not noticing any problems with the car that could result in being a smog problem? (i.e. smog pump"whining" or grinding, EGR sticking or leaking)

im pulling stuff right now because ive never had a problem with Emissions, and i plan on going historic by next year so i dont have to deal with it anyways

 

car runs fine. if you get on it it boogies. im bringing it to a play tomorrow morning, they are going to look over it.... maybe i missed something small and stupid or maybe its something big.... but ill have to see what they say

 

got it back passed.... a check valve was shot and had a bad vac line... all good now tho

 

hi. can you be specific on the check valve please? What check valve was this? I have the same problem with high HC. Thanks.