All my emission results over the past four yrs have been great- .06-.08 opacity. That is really good. Now this year I didn't pass (51% opacity) and then just barely (31%) after:

1)new fuel pressure valve
2)clean air filter
3)new fuel filter and clean pre-filter
4)new oil
5)checked timing (still 15.5*) and fuel pressure (26-27)
6)trans fluid- I know, but what the heck...

The truck will fog a grey cloud when they put it under load on the dyno machine. So at speed they apply the load and on comes the fog.

The only thing I have done to my truck that is different is put in a new radiator. Now the 160*? replacement stat actually does its job. I need to put in the stock 180. Could it be that?

Any ideas will be appreciated. I'd like to at least know whats going on.

Thanks

Jimmy

 

The 10 plate and afc housing are what control opacity (unburnt fuel). I would tighten up the starwheel, and/or slide your afc housing to the cab (this will reduce pre-boost fueling) and maybe slide the plate towards the cab 1/16th of an inch to reduce total fueling. Then crank it back up when you are done.

 

Since you've covered the obvious things first...

Too much fuel or not enough air.
How's your boost doing? Could have a leak.

Worn injectors perhaps with holes too big or a poor spray pattern.
Maybe some injector cleaner will help.

 

I'll check the air and run a cleaner.
I get about 15# of boost at 1/2-3/4 throttle. 20 if I really get on it. I have an after market elbow on there now that went with the #10 plate.

What is weird is all my good tests were with my housing farther forward and the starwheel two revs more to the engine. So its not too much fuel I don't think.

Jimmy