emmsions question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hjalbert · 02-19-2003, 07:01 PM

my emissions were fine under load, but at idle the hydrocarbons were at 457(ppm), and the max is 400, the CO2 at idle was 2.35 %

when i tuned the carb, under load is still fine, and the CO2 at idle went down to .26%, however, the hydrocarbons went up to 1027(ppm) this is very perplexing to me, and i am wondering what could cause this, and if there is any "easy fix" the truck is running good, the way it is, any help would be apprecited. thanks HJ

Low67C10 · 02-19-2003, 09:28 PM

You might have gone a bit too lean (slight lean misfire) when you set the idle mixture, try richening it up a bit, just make sure not to go too rich and fail for CO. If that dosent work make sure the idle isnt set too low, make sure all the tune up stuff is OK (plugs,wires,cap and rotor), and if still no luck, check engine compression.

70shortnphat · 02-19-2003, 09:58 PM

Try retarding the timing some.(just for the test). then if it passes
advance it to where it was. Also make sure you have fresh oil right before the test and that the engine is nice and warm.

hjalbert · 02-20-2003, 04:47 AM

up

Crank · 02-20-2003, 08:56 AM

Do you have to pass emissions? Like out here in certain counties you don't have to take it(such as counties that have farms) and then there's the county I live in now that makes you E-check, but my '67 would never have to be E-check. Because I think it only goes back to like '80 or something. Is Arizona as bad in emissions as California is?
Brandon

72CustomCamper · 02-20-2003, 01:30 PM

hjalbert

What exactly did you do to tune the carb?

Hydrocarbons(HC) are unburned fuel particles and the number one source of high HC on non computer monitored vehicles is running too RICH, not too lean.

Carbon Dioxide(CO2) is a natural byproduct of combustion and low CO2 indicates incomplete and inefficient combustion.

What were the values of NO and CO both before and after?

hjalbert · 02-21-2003, 12:24 AM

well i do believe i have discovered my problem, i started off today by tuning the carb again, but started by turning them all the way in, then i turned em out about 21/2 turns, ran fine, so i started turning them in, and i tell you i turned them all the way in and the truck still ran, i guess, the carb is just worn out, tommorow i am going to put on a different cabr and go get it tested after i tune that and see where i am at, thanks for all the advice. HJ

Project1970 · 02-21-2003, 01:13 PM

That's the same way my truck failed last time through...just had to crank those idle screws in (they were at least two turns too far out each!) and I smoked it.

Just be glad we don't have to get inspected out here. My girlfriend got one hell of a runaround trying to register her Opel GT thanks to the salvage title and the MVD.

02-19-2003, 07:01 PM	#1
hjalbert cracker Join Date: Sep 2001 Location: Wilmington, NC Posts: 1,021	emmsions question my emissions were fine under load, but at idle the hydrocarbons were at 457(ppm), and the max is 400, the CO2 at idle was 2.35 % when i tuned the carb, under load is still fine, and the CO2 at idle went down to .26%, however, the hydrocarbons went up to 1027(ppm) this is very perplexing to me, and i am wondering what could cause this, and if there is any "easy fix" the truck is running good, the way it is, any help would be apprecited. thanks HJ __________________ FOUNDING MEMBER OF THE DRUM BRAKE CLUB Harry John Albert III located in Phoenix, AZ 1972 GMC JIMMY, 1969 lwb Chevy Frame, 1999 bmw k1200 ltc 1992 Kawasaki concours 1991 bmw k75 1973 cortez motorhome

02-19-2003, 09:28 PM	#2
Low67C10 Registered User Join Date: May 2002 Location: Southern California Posts: 66	You might have gone a bit too lean (slight lean misfire) when you set the idle mixture, try richening it up a bit, just make sure not to go too rich and fail for CO. If that dosent work make sure the idle isnt set too low, make sure all the tune up stuff is OK (plugs,wires,cap and rotor), and if still no luck, check engine compression. __________________ No, Its not a 454

02-19-2003, 09:58 PM	#3
70shortnphat "See the U.S.A....." Join Date: Apr 2002 Location: Richmond TX. Posts: 269	Try retarding the timing some.(just for the test). then if it passes advance it to where it was. Also make sure you have fresh oil right before the test and that the engine is nice and warm. __________________ 1970 short bed fleetside 1949 all origional chevy 3600 1974 camaro Richmond , Texas(just S.W.of Houston)

02-20-2003, 04:47 AM	#4
hjalbert cracker Join Date: Sep 2001 Location: Wilmington, NC Posts: 1,021	up __________________ FOUNDING MEMBER OF THE DRUM BRAKE CLUB Harry John Albert III located in Phoenix, AZ 1972 GMC JIMMY, 1969 lwb Chevy Frame, 1999 bmw k1200 ltc 1992 Kawasaki concours 1991 bmw k75 1973 cortez motorhome

02-20-2003, 01:30 PM	#6
72CustomCamper Registered User Join Date: Feb 2003 Location: Bremerton, WA Posts: 86	hjalbert What exactly did you do to tune the carb? Hydrocarbons(HC) are unburned fuel particles and the number one source of high HC on non computer monitored vehicles is running too RICH, not too lean. Carbon Dioxide(CO2) is a natural byproduct of combustion and low CO2 indicates incomplete and inefficient combustion. What were the values of NO and CO both before and after? __________________ '72 GMC C20, "2500 Super Custom", Custom Camper, New 454 '93 K2500 Suburban, Old 454 (157K)

02-20-2003, 08:56 AM	#5
Crank Registered User Join Date: Aug 2002 Location: Crittenden, KY Posts: 1,964	Do you have to pass emissions? Like out here in certain counties you don't have to take it(such as counties that have farms) and then there's the county I live in now that makes you E-check, but my '67 would never have to be E-check. Because I think it only goes back to like '80 or something. Is Arizona as bad in emissions as California is? Brandon

02-21-2003, 12:24 AM	#7
hjalbert cracker Join Date: Sep 2001 Location: Wilmington, NC Posts: 1,021	well i do believe i have discovered my problem, i started off today by tuning the carb again, but started by turning them all the way in, then i turned em out about 21/2 turns, ran fine, so i started turning them in, and i tell you i turned them all the way in and the truck still ran, i guess, the carb is just worn out, tommorow i am going to put on a different cabr and go get it tested after i tune that and see where i am at, thanks for all the advice. HJ __________________ FOUNDING MEMBER OF THE DRUM BRAKE CLUB Harry John Albert III located in Phoenix, AZ 1972 GMC JIMMY, 1969 lwb Chevy Frame, 1999 bmw k1200 ltc 1992 Kawasaki concours 1991 bmw k75 1973 cortez motorhome

02-21-2003, 01:13 PM	#8
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	That's the same way my truck failed last time through...just had to crank those idle screws in (they were at least two turns too far out each!) and I smoked it. Just be glad we don't have to get inspected out here. My girlfriend got one hell of a runaround trying to register her Opel GT thanks to the salvage title and the MVD. __________________ Project1970 - LS1 Swap Complete!



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