Emissions

[LTurner]

A friend of mine has a 92 cummings that just won't pass emissions. It is putting out too much particulates. The engine really pours the black smoke on take off and doesn't seem to clear up. We're wondering if this is an injector problem or the turbo isn't pushing enough air. Any suggestions. It's an auto with 150k.

 

[BILLUA]

First of all, the engine is a CUMMINS not a cummings... Check all the piping related to the turbo. And yes,it is possible that an injector is bad. . Fairly inexpensive and easy fix. .

 

[Greenleaf]

Yes. PLEASE change your signature to "CUMMINS" You'll gain much more respect 'round here.



If the pump AFC is adjusted for perfromance reasons or the pump was tuned by the PO you can detune said pump to limit the flow as well as limit the throttle lever travel by way of the gov speed adjust screw.



GL

 

[dpuckett]

I had one that barely passed emissions, but I suspect a bad injector. Do all the adjustments previously mentioned (may have to do this for the e-test, then after passing, revert back to "original" settings), then see if it passes. Also, when adjusting the AFC, turn the pin taper to the lean setting to further limit fuel.



BTW- what is the particulate limit where it is failing? Mine makes 30psi boost, and has some haze under WOT til the turbo clears it up (2-4sec), then just a light haze if the lighting is just right. And my pump needs worked on.



Daniel

 

[LTurner]

Cummins

I deserved that. In too big of a hurry I guess, anyway thanks for the info on what to look for. I'll check the AFC and gov limiter setting, before we look at purchasing new injectors.

 

[LTurner]

He doesn't have his emissions sheet with him right now, but was thinking the particulate limit was 70 and he was reaching 90-93.

 

[WyattEarp]

just a guess but sounds like the pump is turned wide open, hence reading what dpuckett said about his truck with a pump that needs work... i could be wrong but black rolling smoke means somewhere alot of fuel is being introduced into the system. . just my . 2cents

Hope he gets its fixed, thats horse crap, emmissions. catching 4th gear going up hill and getting on it, mine will engulf anything behind me but its not black, its a greyish black. Comes in handy for those (bumper riders) lmao, which i friggin hate!

 

[RWWinslow]

One more quick and easy set of checks - since you are not that far over on particulate. . . . check your air filter - it might be quite dirty. Check your turbo charger hoses and clamps - they can leak quite a bit of boost pressure. I have seen this combination of problems cause a number of B series engine emissions problems.

 

[JLEONARD]

I would turn the fuel screw back in a turn, make sure the fuel pin is on the min side, New air filter, then take that Cummins back thru again.

I can emit a grayish black cloud like Wyatt described, and I passed emissions easily... heck it only takes 15. 6 horsepower to run the rollers for the sniffer... shouldn't be belching out anything at that level.

Hope this helps.

 

[GBechtold]

Which states are all of you guys from? I'm in Pa. and we don't have emmisions YET but I'm affraid they won't be too far down the road

if the tree huggers have anything to do with it #@$%!

but thats one nice thing about a diesel they're easy to detune for just such a

situation.

Can anybody explain why it is that a Cummins that smokes like a freight train get's as good if not better fuel mileage than a new truck but won't pass emmisions?

 

[Greenleaf]

Diesel fuel contains loads more btu than gasoline among other techy facts like when a spark plug ignites the gas/air mix it all over. The fuel in there is the fuel in there. It's burned. The diesel will inject fuel and when it lights off, there is more fuel to follow and burn to keep the combustion pressure pushing down on top 'ye piston.



A diesel doesn't really have an optimum air/fuel ratio. It can be very lean and then very rich.

 

[dpuckett]

I thought the optimum air/fuel ratio was as little fuel as possible to produce the power needed.



I had a 91. 5 that barely passed emissions in 02 (35% of 40% allowable); thing got 23-24mpg regularly. Had I known I could get a driveshaft built for <$500, I would have kept it. But I made a $1500 profit in 4mo on it.



DP

 

[JLEONARD]

I thought the optimum air/fuel ratio was as little fuel as possible to produce the power needed.

Yes and that's continuously variable in our application. And our engines were set up that way initially... until we all frig around with them.

Funny... so much time and effort goes into getting these fine tuned when they're built... and guys like us frig it all up with a few turns of a screw, changing components around a bit...

Ok but it's good friggin'. :-laf

 

[RWWinslow]

Diesel emissions studies are on the cutting edge of current engineering and scientific study - to get an appreciation for how difficult the problem is go to the following study on diesel particulate emissions



http://www.me.umn.edu/centers/mel/reports/crce43es.pdf

http://www.me.umn.edu/centers/cdr/index.html this is the web site for the center



For those that face the emissions testing, ensure that you are using the highest quality fuel available particulate formation is a function of the fuel quality - and you might want to consider dosing your fuel with a little bit of jet fuel, kerosene, or #1 diesel. (One way to accomplish this is to go through the test with 1/4 tank of fuel with appropriate dosing (per previous sentence) and then fill the tank up with straight #2 to avoid any long term lubricity issues. ) Finally, ensure that the engine is hot - diesel particulate formation is favored at low combustion temperatures and low head / water temps.



This is a good topic that most of us will probably be faced with in the future.

 

[JLEONARD]

We have had emissions testing for several years here in Ct. The first time I went thru I was sweating it a little... I turnd my fuel pin to the wimp side and passed with flying colors.

The second time I just left everything alone..... still passed easily.

I talked with the guy who was doing the testing at this particular place... he had two years of experience already... . he said only one diesel vehicle failed... an old Mercedes that literally smoked up the bays at an idle. . he said it was really smokey.

My son took his 94 CTD thru... that thing smokes like no tomrrow when you press the go pedal... (300 marine injectors, #6 plate,you know the story) ... he passed with no issues.

So I'm thinking right now at least emissions testing is pretty easy to pass in this neck of the woods.