Failed Emissions a 4th time!
 

Ok '86 GMC 305 with a 600cfm Holley carb and I have failed emissions again for the same things High CO and High HC I have Changed the oil, Changed the PCV valve, put in plugs that are 2 heat ranges hotter, rejeted the carb for my altitude, set the floats, and adjusted the air fuel mix and the truck is running great!... I have all of my stock emissions controls hooked up accept the EGR Valve the PO took it off when he put the holley on because of a clearance issue I am stuck and can not figure out why this thing wont pass... Do I have a bad power valve? Bad Cat? Im not really good at diagnosing emission issues and dont want to start throwing parts at it and it not solve my problems any help would be great thanks...

Re: Failed Emissions a 4th time!
 

What were your numbers & what are the limits?

Re: Failed Emissions a 4th time!
 

Sorry forgot to post that lol
HC limit is 4.000 my reading 6.1857 Gpm
CO limit is 40.000 my reading 115.0876 Gpm
Posted via Mobile Device

Re: Failed Emissions a 4th time!
 

you could try using seafoam. or I have heard of people using alcohol mixed in the gas to pass the test.

Re: Failed Emissions a 4th time!
 

High CO and HC means "rich." I'll bet the NOx was WELL within limits. Did you fail at idle, or cruise?

Re: Failed Emissions a 4th time!
 

To be honest I don't know colorado has this stupid bar graph readout because they run on a dyno but if I had to guess I would say cruise
Posted via Mobile Device

Re: Failed Emissions a 4th time!
 

Had the same problem everytime i went until the guy at the test center showed me that. Of course the first time there was a I can make it pass for you fee, which is why i always did it myself. I always used to pullover just before i got to the test center and retard my timing and lean out the mixture, ran like crap but passed everytime.

Re: Failed Emissions a 4th time!
 

I wouldn't know about that, i haven't ran a catalytic converter on the 82 K10 in probably 25 years ROFL

But i do have a Cali smog pump off either a 79 SWB with a 350 or the 79 Firebird with the 400 Pontiac in it hanging in a shed.

Re: Failed Emissions a 4th time!
 

Hee Hee Hee of course you don't have a catalytic converter on your truck
and of course your Cali smog pump is hanging in the shed

BTW, emission controls are to protect the environment.
Posted via Mobile Device

To the OP, they won't fail you anyways for the missing EGR?


I hear you can find almost new ones in OKElamona
Posted via Mobile Device

Re: Failed Emissions a 4th time!
 

Not to mention they suck HP, you think this was bad the first thing my grad-dad did was yank the converters off all his trucks, i bet even the last one he bought which was like a 97 F150, Now with the 00 stepside or my 06 sierra i wouldn't dream of yanking the converter off. My 82 isn't a daily driver, but has been a farm truck since i parked it back in 95 when i quit driving it in highschool.

And i didn't remove the converters, the original owner did (aka dear ol' dad)

Re: Failed Emissions a 4th time!
 

Ya they don't care about the egr missing there is a home made block off plate covering the port anyway
Posted via Mobile Device

Re: Failed Emissions a 4th time!
 

I bet if you put that EGR valve back on, you pass...

Re: Failed Emissions a 4th time!
 

Wish I could I don't have another carb to put on.... there is a vaccume port that sticks off the side of the holley that is right in the way of where the egr valve sits so I cant get it back on

Re: Failed Emissions a 4th time!
 

Can you put on a spacer between the carb and intake to lift the carb up enough to get the egr on.

Re: Failed Emissions a 4th time!
 

It has a spacer plate already

Re: Failed Emissions a 4th time!
 

The EGR will likely only reduce NOx. If the carb was tuned ~for~ EGR, I would expect it to run lean with the EGR missing. Lean misfire would show up with lots of HC, but very little CO.

You could try setting the float lower than optimal, this should lean out ~everything~.

Or change main jets, assuming that it ~is~ cruise where you are failing.