How to lower hydrocarbins
Thread Starter
Intermediate
Joined: Mar 2007
Posts: 44
Likes: 0
From: Palo Alto CA
How to lower hydrocarbins
What are some things people have done to lower the hydrocarbin output to pass smog? I'm not running a stock tune, but I've adjusted the BLM to be almost exactly 127 in the ranges they are testing. CO2 and NOS are all in the green, but I still can't seem to pass. The car passed two years ago which was less than 5,000 miles in my case. I had to replace the plugs and the PCV valve at the time.
A little info on the mods:
I'm running a 170 thermostat and have the fans comming on to keep the temps low. MAF is descreaned and ported, K&N airfilter with a cut out air box. FIC Blue Demon 24LB Universal Balanced Fuel Injectors. Adjustable fuel pressure regulator.
Thanks for any suggestions.
A little info on the mods:
I'm running a 170 thermostat and have the fans comming on to keep the temps low. MAF is descreaned and ported, K&N airfilter with a cut out air box. FIC Blue Demon 24LB Universal Balanced Fuel Injectors. Adjustable fuel pressure regulator.
Thanks for any suggestions.
Melting Slicks
Joined: Jul 2006
Posts: 3,356
Likes: 1
From: Chesapeake Va
Post your emissions report. How far off are you? Are you cammed?
High HCs can be caused by many things. Is your AIR functional?
If your CO isn't high, it's not rich. Could be a slight misfire. Could be the temp is too low. May need to add some timing at idle.
Hard to say without at least seeing the emissions report.
High HCs can be caused by many things. Is your AIR functional?
If your CO isn't high, it's not rich. Could be a slight misfire. Could be the temp is too low. May need to add some timing at idle.
Hard to say without at least seeing the emissions report.
Former Vendor
Joined: Nov 2006
Posts: 2,482
Likes: 3
From: Carmichael ca
Hydrocarbons are unburned gas, usually caused by a misfire. To fail at 15 and 25 mph, the miss should be noticable. How are all the tune up parts, cap, rotor, plugs, wires? How many miles on the engine, and injectors?
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Retard the ignition timing a few degrees. This will cause the burn to take place down stream towards the cat helping to heat the substrat.
Thread Starter
Intermediate
Joined: Mar 2007
Posts: 44
Likes: 0
From: Palo Alto CA
Post your emissions report. How far off are you? Are you cammed?
High HCs can be caused by many things. Is your AIR functional?
If your CO isn't high, it's not rich. Could be a slight misfire. Could be the temp is too low. May need to add some timing at idle.
Hard to say without at least seeing the emissions report.
High HCs can be caused by many things. Is your AIR functional?
If your CO isn't high, it's not rich. Could be a slight misfire. Could be the temp is too low. May need to add some timing at idle.
Hard to say without at least seeing the emissions report.
Here are the numbers: (Sorry about the formating)
Speed--CO2(%) O2(%) HC (PPM)----CO(%)-------NO (PPM)
15 MPH-14.01---.70----87 (Max 84) .20 (Max .49) 511 (Max 692)
25 MPH-14.20---.55----61 (Max 49) .16 (max .46) 286 (Max 711)
I just changed the plugs and PCV valve last night. Fuel injectors have less than 5000 miles on them. Engine has about 117K. Opti was replaced around 75K when the watter pump blew. The internals of the engine are stock, so no cam.
Thanks again for looking at this for me guys. I've got 5 more days to figure it out before my registration expires. So if I have time I may try a retest this weekend with my new plugs.
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
I would retard the timing to stock if you have added over the stock base timing and if it is stock now take out 3 degress and bet that sneeks you under the limit.. One question how old is the cat or cats and is the air pump all working.. getting it good and hot wouldn't hurt either.. as in normal as designed temps.
Edit
oops did not read carefully enough you have opti so no changing the timing unless with a chip burn from what I understand.. That leaves you with cats working air pump working and proper tune up.. what is the integrator llok like and are the o2 cross counts nice and fast or sluggish. Could be a lazy o2 letting it stry too far into the rich side or plugged dying from old age not seeing the proper o2 reading. When that happens they usually get slower as well.
Edit
oops did not read carefully enough you have opti so no changing the timing unless with a chip burn from what I understand.. That leaves you with cats working air pump working and proper tune up.. what is the integrator llok like and are the o2 cross counts nice and fast or sluggish. Could be a lazy o2 letting it stry too far into the rich side or plugged dying from old age not seeing the proper o2 reading. When that happens they usually get slower as well.
Last edited by ddahlgren; Jul 25, 2009 at 09:28 PM.
Thread Starter
Intermediate
Joined: Mar 2007
Posts: 44
Likes: 0
From: Palo Alto CA
I would retard the timing to stock if you have added over the stock base timing and if it is stock now take out 3 degress and bet that sneeks you under the limit.. One question how old is the cat or cats and is the air pump all working.. getting it good and hot wouldn't hurt either.. as in normal as designed temps.
Edit
oops did not read carefully enough you have opti so no changing the timing unless with a chip burn from what I understand.. That leaves you with cats working air pump working and proper tune up.. what is the integrator llok like and are the o2 cross counts nice and fast or sluggish. Could be a lazy o2 letting it stry too far into the rich side or plugged dying from old age not seeing the proper o2 reading. When that happens they usually get slower as well.
Edit
oops did not read carefully enough you have opti so no changing the timing unless with a chip burn from what I understand.. That leaves you with cats working air pump working and proper tune up.. what is the integrator llok like and are the o2 cross counts nice and fast or sluggish. Could be a lazy o2 letting it stry too far into the rich side or plugged dying from old age not seeing the proper o2 reading. When that happens they usually get slower as well.
Thanks.
Last edited by vetteodyssey; Jul 26, 2009 at 12:27 AM.
Racer
Joined: Apr 2001
Posts: 413
Likes: 0
From: glendale Arizona
The tune is not stock. I tinkered with it quite a bit a few years ago. But I don't remember adding timing at idle. O2 Sensors where replaced about a year ago and the readings a pretty quick. The cats are 3-4 years old. I am having trouble finding my stock tune. Which because I've installed the 170 thermostat and lowered my fan temperatures it does run a lot cooler at idle. That I suspect is contributing to my problem. Does anybody know where I might be able to purchase/download a stock tune?
Thanks.
Thanks.
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Thread Starter
Intermediate
Joined: Mar 2007
Posts: 44
Likes: 0
From: Palo Alto CA
Sometimes you have to do desperate things to pass smog ( I license my 91 out of county ) go to Home Depot and get some denatured alcohol with about 1/2 tank of gas pour it in the tank and make sure it is mixed up and go to smog then go immediately and fill the tank, this should get you a pass.
I did find my stock tune, but after thinking about it might not be the best idea. I've installed a larger MAF, which I re calibrated the computer for. If I put the stock tune back in I'll have a few hours of driving and data logging to get the stock tune working well with the new MAF.
Last edited by vetteodyssey; Jul 27, 2009 at 06:17 PM.
Thread Starter
Intermediate
Joined: Mar 2007
Posts: 44
Likes: 0
From: Palo Alto CA
Well, I failed again. I had the guy diagnose the problem this time and he said my cats aren't working. They only about 4 years old, but he said after market cats don't last very long and that's probably why they failed. Then he drops the bomb on me. The cat on the passenger side is discontinued and there are no more OEM versions in the entire country! And they just changed the rules in California and they are not allowed to install after market ones any more. Only OEM, of which there are no more. So it sounds like I'm about to loose my baby.
Or, I need to find an unscrupulous muffler shop that will install aftermarket cats so I can pass SMOG, then I'll probably be right back here in two more years.
Words cannot describe the pain right now...
Or, I need to find an unscrupulous muffler shop that will install aftermarket cats so I can pass SMOG, then I'll probably be right back here in two more years.
Words cannot describe the pain right now...
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Time to either learn to wrench or pay a friend to do it for you and install aftermarket cats and get it done they have no idea when the cats were changed..Last week last month last year.. Just go to a different test station... I am sure you can find them cheaper than this but a start..
http://www.car-sound.com/02product/s...ayproducts.asp
http://www.car-sound.com/02product/s...ayproducts.asp
