Need help with emissions!!

[Rains]

i took my 95 GT in to get smogged today, and it failed.

The results read that during idle, the HydroCarbon (HC) out put is too high... not in the higher rpms, just idle

anyone had this before?? What should i look for??

he said i may have a vacuum leak, or maybe somethings up with the plugs or wires???

i dont really know where to start looking, any help would be great

thanks

btw
the faster i can get this fixed, the sooner i can bolt on my off road h pipe

 

[sleeper89]

when was the last time you did a tune up to your ignition system? FWIW when i smog tested my car it passed all 3 parts of the dyno test (HC, CO, NOx) very easily. but then she failed one part of the idle test (i'm pretty sure it was NOx). it turned out i had *slightly* too much gap on a couple plugs and she wasn't burning completely at idle. at the time i was running about .070" gap so i took it down to .065-.068 (going from memory) and retested my baby. she passed all the tests. anytime i see people fail the idle test i immediately think bad ignition. also it's a good idea to run about 10* base timing for the test and drive the piss out of your car for about 15minutes immediately before you pull onto the rollers to properly heat your catalytic converter.

-steve

 

[CobraGT87]

in calif you can back the timing down to 8* legally. do that and run 87 octane. that will drop your HC's at an idle quite a bit right there.

Scott

 

[Rains]

well, i just replaced the spark plugs with autolites, and i'm going to go back and check them to see if they have the correct gap..... Also, i'm going to try and check the wires, cap/rotor, do a decent inspection

also, my timing is at 10*....

i'm running 89 octane... and i think next time i fill up i'll go with 87.

at idle, the max HC allowed is 100~ i'm putting out 230 HC

thanks for responses

anyone else?

 

[sleeper89]

definitely run the 87 octane. extra octane is actually going to hurt performance if it isn't required. after the e-test get yourself a timing light, fill the tank with premium, and advance the timing as much as you can (without ping). good luck with the test.

-steve

 

[Rains]

thanks

side note... i think i do have a air leak some where, i think it sounds like its coming from behind the upper intake manifold, by the firewall.....

anyone have thsi problem?

 

[Notchbck93]

Be sure to change your oil before you go. I have had many experieces with failed cars and I have also seen a car fail because it had dirty oil in it. The driver did a bunch of short trip driving. Also you may want to back your tps down as far as poss at idle and make sure your fuel pressure is in the correct range. If nothing else , create a vacuum leak ,, a small one , that will lean out the mixture,, though if it is too lean it will cause a misfire as well. Use your best judgement. Oh ya and how old are your O2's.?? A lazy O2 will cause a car to fail and idle test.

 

[DavidF]

Its allways a good idea to do a tune up/oil change before a smog test, that way you know all the "basics" have been checked.