Emmissions puzzle
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Joined: May 2002
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Emmissions puzzle
Here's on for the guru's of 300 land.
My six will pass emissions at the Delaware state Official testing only at high rpm (2250)
HC (ppm) has to be under 400 at idle and 2250 rpm.
At idle it's 813, high rpm 256.
CO(%) has to be under 4.00
At idle it's 6.65, high rpm it's 2.02
She has fresh plugs, cap rotor, and carb rebuild.
#'s came down from 1796 hc/8.6 co after carb rebuild.
Any ideas on which way to go?
My six will pass emissions at the Delaware state Official testing only at high rpm (2250)
HC (ppm) has to be under 400 at idle and 2250 rpm.
At idle it's 813, high rpm 256.
CO(%) has to be under 4.00
At idle it's 6.65, high rpm it's 2.02
She has fresh plugs, cap rotor, and carb rebuild.
#'s came down from 1796 hc/8.6 co after carb rebuild.
Any ideas on which way to go?
Super Moderator
Joined: Apr 2004
Posts: 34,517
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Rich at idle. Got idle adjustment screws? Lean it till it misses, give it back only slightly.
The old way was to adjust to best idle, then 1/4 turn lean. With high HC, lean it out a bit.
Don't allow a miss at idle though--that will make the HC jump.
If you do have a miss, check for vacuum leaks in the intake, carb base, vacuum lines, PVC, brake booster, carb.
The old way was to adjust to best idle, then 1/4 turn lean. With high HC, lean it out a bit.
Don't allow a miss at idle though--that will make the HC jump.
If you do have a miss, check for vacuum leaks in the intake, carb base, vacuum lines, PVC, brake booster, carb.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
What was said so far is right on the money, and I'd add that you may want to clean out the intake manifold. If the truck is not driven a lot, you can get stuff condensing on the inside of the intake from the PCV flow. It will hold some gasoline that eventually will be evaporated and burned, but can make the mix over-rich at idle. My Ranger would not pass its first SMOG test in CA, and I think it was intake deposits messing up the mixture. I removed the throttle body and sprayed cleaner (catalytic safe) all around and let it sit for several hours before starting it up. Ran smoother and passed emissions test with no problem.
tom
tom
