Snap Opacity

[Dale Reed]

Apparently I almost failed the Opacity Snap Test yesterday at the Renton, Washington Vehicle Station. The truck tested 53% out of the required 55% and I had to Snap nine times instead the promised three.



If I had read the comments here at TDR *before* taking the test I would of been far less aggressive about stepping on the accelerator.



I don't remember ever taking this test before. Is my memory failing or is the Diesel Snap new in Washington State? I don't think my truck smokes unless I attempt to accelerate WAY too fast up a hill.



But, what I really want to know, does this mean that my truck is smoking more than it should? What should I do to fix it?

 

[CMullen]

sounds more like a chewing gum snaping contest, for those of us who live elsewhere can you enlighten on the purpose and method of the "snap opacity" test



thanks

Chris

 

[Dale Reed]

Purpose? Hey, do you want my opinions or the governments? I am a libertarian orientated 70 year old who many many years ago wintered a couple years in Antarctica on a couple Navy bases so learned some words that I doubt that the sensitive TDR trucker folks may not want to hear. At least not on the last day of 2005.



Method? Tranmission in neutral. I was told to push the accelerator hard and fast until the governor kicked in then let off. Three times with the device not in the exhaust pipe and then the test operator said three more times with the measuring device inserted. But I had to do it many many times with a sorta concerned look on the operators face.

 

[McLaughlin]

Apparently I almost failed the Opacity Snap Test yesterday at the Renton, Washington Vehicle Station. The truck tested 53% out of the required 55% and I had to Snap nine times instead the promised three.



If I had read the comments here at TDR *before* taking the test I would of been far less aggressive about stepping on the accelerator.



I don't remember ever taking this test before. Is my memory failing or is the Diesel Snap new in Washington State? I don't think my truck smokes unless I attempt to accelerate WAY too fast up a hill.



But, what I really want to know, does this mean that my truck is smoking more than it should? What should I do to fix it?

Just a guess but I'd suspect it is an attempt by the "clean air" folks to restrict those "dirty-smelly " diesels. Sounds like they are targeting people that are doing the high horsepower diesel mods .

 

[WyattEarp]

Yeah i was thinking the same thing , what the heck is a snap opacity test, sounds like some tree hugger gov't official technical term.

 

[Dale Reed]

http://www.google.com on "Snap Opacity"

 

[JLEONARD]

When I tested 2 years ago in Ct they did a snap test on mine. But I had a gentle operator who didn't believe in burrying the go pedal... he gently revved it up to about 1500 and called it a day. But since I rotated the fuel pin to "min" there was barely a trace registered from the tailpipe.



Jay

 

[CMullen]

HA! good for you Jay,

guess the guy wondered if your truck was running "is it alive?" Here in PA they just bend down and smell the exhaust. For gassers they have an emissions test that is expensive. Guess when we get ULSD we'll be getting tested more rigorously.

 

[RBergman]

dale,

its not new i have had to do it every other year for the last 6 years

(at least) i will try and dig out my slips

 

[Bob4x4]

We did an opacity snap idle test on 2 hot rodded 12vs a while back to test a chemical co. s claims. It works!We did a # of snap idle test to get a base line on both trucks. The 94 (mine) did a clean 2% the 1st gen did a much higher # I dont remeber the exact but 30-40 range I think. We filled the filter canisters with the Chemical Redid the test the 94 dropped to . 6 and the 1st gen dropped to a single diget. Of coarse the chemical co. claimed the results would last I think the cleaner was just a lot cleaner burning than old #2. So if you are border line just bring a can of fuel additive to your next test fill your filter and pass with flying colors. .



Bob

 

[TKingsbury]

What I have found doing these tests on our fleet of County owned vehicles is this; you normally get the high #s from having too much low boost fuel. They normally clean up as the RPM goes up. What you need to watch is that initial puff. You could play with your AFC adjustments to see if it helps. If your #s are that high, it won't solve all of your problems, but it could make it much easier to pass. Just for a little comparo, I tested my truck at 6% as I recall. That was with 1/2 turn on the smoke screw, afc cone at full deep, big hole in the air box and no muffler, all else stock. Our stock 93 at work was about 4. 5%.

Travis. .