When I got my truck back in early September, the day I got it I had it SMOG checked and it passed with flying colours. SOOOO. Fast forward to three months down the road, and now that I HAVE to get it plated, I have a slight problem! It failed SMOG yesterday on idle it had almost twice the allowable CO but everything else was good. It even passed on high rpm on both CO and HC. How the hell do I adjust the idle CO? Is there a way? Or is that done by the computer? I am thinking it is a partially clogged low speed injector for some reason. BTW if it means anything, my air filter was also very dirty and the gas cap failed smog too....

heres the readings...

 

fixing the gas cap and cleaning or replacing the air filter is a good idea. did you bring it into the emissions place hot? could maybe try running a bit higher octane gas.

 

I replaced the gas cap and air filter and saw that the air filter was the wrong size in the housing. Plus it was very dirty. I also got some of that stuff called G2P garenteed to pass, an filled up with premium since I had low test in there. I hope with these things it will pass tomorrow. Oh, and yes it was fully warmed up when I took it in for the test.

 

Your running rich at idle...I didn't see any truck info what year, eng, etc are you trying to get through?

 

1991 w150 4 speed, 318, all dead stock with all original equipment. No check engine lights or displays on the dash. I am chancing my plugs today as well just for the hell of it.

 

you should really put that info in your sig or put it in the vehicle information box. then we would not have to ask you the same question every time you ask for info or help.

 

Sill you should check for codes. Also check for dripping injectors while it is idling.

 

Maybe try turning the idle up. Isn't the high limit for the idle test around 900rpm?

 

it is idling low, or was around 735...

 

try and spike the gasoline with methanol. a LOT