Can anyone that lives in the Denver area tell me how tough the diesel emissions tests are? I don't have a muffler, but can turn the smarty down to half power for the test if that makes a difference. I also have a '72 chevy with a 454 and is a little on the rich side @ about 5mpg that I'm concerned with passing. Any info/experiences would be great. thanks

 

do vehicle models prior to 1975 need emissions?

 

Yes but 1960 and older don't

For diesel passenger vehicles, the test is just a snap idle opacity test, should cost around $60. Don't go to a test facility that puts you on rollers, it costs more and isn't needed. They shouldn't say anything about a muffler, only a cat if your vehicle came equipped with one. If they do bother you about the muffler just tell them you have one under the hood.

For your chevy, it will be similar, the test is an idle and high idle test. If its too rich, you'll need to tune it down, as your HC's will probably exceed the limit. If you're too rich in Kansas, you'll be way rich here in denver.

 

WOW! Colorado more stringent than California? Cali is 1975 and older are smog exempt.

 

Good point. ^^^^^

I'd say you need to change the jets.

Also, a member for 5 yrs and 4 months and only 13 posts

 

Have friends with Diesels in Colorado, they go out to the rural parts and register the trucks!

 

When I lived in Chicago, my truck was exempt from testing as it was diesel, you only had to bring it in and show them. That will not be the case with 2007+ models.

However, my gas engined cars needed testing, but it never cost anywhere close to $60 for a test. I think the testing was on the state, you just had to bring it in.

 

Heavy Duty VehiclesGasoline-powered heavy duty vehicles that are model year 1982 or newer are tested with the idle test rather than the I/M 240 test. They must be tested at an I/M 240 testing station. Inspection fee is $25.

Diesel Testing
Diesel vehicles are not inspected by Air Care Colorado but instead fall under the oversight of the Department of Public Health and Environment, and need to be taken to state-certified independent facilities. Fees vary by location and a passing certificate is valid for one year.

New-model, light-duty diesel vehicles are granted a two-year emissions test waiver.

http://www.dmv.org/co-colorado/smog-...sting_Programs

Small Fleets and Individuals
Small fleets and privately-owned diesel vehicles take part in the Diesel Opacity Inspection Program. This program is for all light-duty diesel vehicles as well as heavy-duty diesel vehicles not subject to the large fleet self-certification program. The Diesel Opacity Inspection Program requires that eligible vehicles be inspected on an annual basis by private, state-licensed diesel inspection stations. New light-duty diesel vehicles are exempt from testing for four years. The program applies only to the Automobile Inspection and Readjustment Program area and utilizes a loaded mode dynamometer-based test.

http://www.cdphe.state.co.us/ap/mobile.html#Diesel Emissions Control Program

 

[QUOTE=apwatson50;2540511]Yes but 1960 and older don't

For diesel passenger vehicles, the test is just a snap idle opacity test, should cost around $60. Don't go to a test facility that puts you on rollers, it costs more and isn't needed. They shouldn't say anything about a muffler, only a cat if your vehicle came equipped with one. If they do bother you about the muffler just tell them you have one under the hood.
QUOTE]

Well I'm not in Denver but just south in the Springs. My truck just went in for emissions testing last week. We have all of one shop that will emission a diesel here and it's a dyno type test. I just take my ez off and pay the $50. They always have to hand write in fake(?) opacity numbers cause the machine prints out zeros. maybe is an El Paso county thing cause we don't emission gas cars/trucks here?

 

Emissions testing for gas vehicles falls under a differant gov't agency than a diesel truck does. Part of the AirCare program had provisions for stopping the program when air quality reached a certain level of cleanliness. A few years back, most of the state did, and the program was stopped. But, the diesel program has no such provisions. So, the entire state still does diesel testing on schedule, regardless of air quality.