wont pass emissions

[Inspector]

My ol 93 won't pass emissions testing. The opacity test wants a 20 but all we can get it down to is 28. We have done all the usual stuff, oil and filter, fuel filter, fuel treatments and driven hell out of it before testing. The pump has been turned up an 1/8 and has passed this test like that for the past many years. Also we are a line advanced on the pump. In my opinion the way the test is performed is the problem but you can't tell em how to do it. This truck runs great with very little smoke and was retired from working hard several years ago.
Does anybody have a secret potion that would pick up at least 8 points on the test?
Vitals--------93 C3500, 168K original miles. 5 speed w/gear vendors. 3 1/2 inch exhaust. Dual therms and pump. Kennedy lift pump.
Denny

[DennisG01]

We don't have emissions for diesels (at least older ones, anyways) around here so I don't know what all is involved in the test. Is it that "snap test" I've read about where they quickly jam the throttle down? I'll probably get a little flack for this, but what if you glued a little piece of wood to the underside of the pedal to keep it from going as far down to the floor? Not too big (or thick) so it's obvious... Of course, the "real" reason you have the wood there would be to help you control your fuel economy ;)

[Robyn]

How many miles are on the injectors ??

If the injectors have a lot of miles, then a fresh set will likely clean up the burn.

Missy

[Inspector]

The injectors were replaced around 90k. I'm thinking I replaced the 4911 about the same time. The pump was courtesy of a 1st rendezvous drawing in Stevensville at Jim's. I was very fortunate and lucky to get that gem.
It had been on the shelf at home pleading with me to get to work. So ordered up some new not rebuilt injectors and return lines kit and did the job. So there are a few miles on the injectors now.
Glad you are improving quickly as I know you can't stay out harness for an extended time. Its tough to fly with a bad wing but we all know that won't stop you. Thanks for replying Robyn. We need your knowledge.
Denny

[land's end 4x4]

Hi,

How is this test peformed? Is it on full trottle for a moment....
I supose you can just adjust the max. (how is it called) of the trottle.

All diesel engines will rev up to the minimum rpm required but will behave way more "enviromental"

For sure you will lose lots of power, but just re-adjust after the test.

Hope this helps.

[Kennedy]

#1 diesel?

[Inspector]

Hi John....
Sounds good. We'll give that a try.
The test is a snap check. They bring the speed up to 55 going thru the gears to 4th. Then let it stabilize. Then snap it to wide open throttle. The machine looks at the smoke optically and comes up with an opacity figure.
Denny

[joed]

May try backing down the timing - doesn't advancing the timing increase the smoke somewhat?

Good luck.

Joe.

[Inspector]

Backing the timing off to the mark is in the plan if #1 doesn't do it. Its so close to passing, within 5 points.
Denny

[EdHale]

I'm glad I live in a state where no emissions testing is done for any vehicle.

[Inspector]

Well folks the ol 93 has passed its emissions test. All it took was a couple of gals. of Kero as #1 just wasn't available. As it turns out the fellows that originally tested it didn't do it right. The fellow that did the test did it the right way. The numbers were taken at the beginning of the snap and at full throttle. Last number was 12.3 and the first number was 1.3. A far cry from 28 parts per million. This truck has always passed with low numbers and we just couldn't understand what could be so different. It did cause us to do a full clean up and service and that was a good thing. Old Hips is now legal again to be doing its thing. It has been a great dependable truck and has always had TLC.
Denny

[trbankii]

Good to hear! What were they initially doing wrong with the test?

[DennisG01]

Good to hear! What were they initially doing wrong with the test?

Ditto. Not knowing much about these tests, I'm curious, too.

[Inspector]

They would bring it up to 55 in 4th gear on the rollers but would not stabilize it but would pump the gas pedal and then snap it to WOT. Not being stable before the snap left the exhaust system loaded and not relatively clear thus causing a false end reading on the test equipment. Fortunately the last tester knew what he was doing. They caused a lot a hair pulling knowing that this truck should have passed with no problems.
Denny

[trbankii]

Thank you for the explanation. We don't have emissions on diesels here (yet), but it shows one has to be aware of how the test should be done so that they don't pull a "fast one" on you. I'm sure that there are any number of ways for the operator to make a vehicle fail by not doing the test to spec.