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emissions woes

schickdog

By schickdog,
in The Garage

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schickdog NPORA Newbie

schickdog

Posted
Posted

Well, i fixed my starting issues, now on to how-well-she-runs. Actually, she runs like a top, the a/c blows icecubes, and gets 22 mpg city. take that. The problem is she won't pass inspection. Take a stab at this one. The truck has too high hydrocarbons at idle. O2, Co2, and CO are good, and hC' are fine at 2500rpm, but again, at idle is ~330.

 

All vacuum lines are accounted for. I ran Seafoam 1 month? ago. SHe has new NGK plugs, wires, cap, rotor, PCV valve, air filter, and the EGR valve and the AIC valve are working fine.

 

So i am assuming that she's running too rich. any thoughts, and if so, how do you lean it out?

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mws NPORA Old-Timer

mws

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A lot of the TBI'd pathies have this problem. Mine does.

 

I sneak it through by turning the idle speed up a bit. Just 50 rpm above the recommended idle speed does it for me! I use a smog tech I know, and have him hook it up and I just turn the idle speed up in tiny increments until the HC reading plummets - just a few rpm makes a huge difference. Haven't figured out why yet....

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Precise1 NPORA Old-Timer

Precise1

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Yes, exactly as Martin says, my old D720 needed the same treatment. As a matter of fact, it was the smog guy who showed me the tweek... Better compression/less blowby/slightly different timing?? It does help... Don't bother sneaking, run it at the highest rpm allowable.

 

Also, a fresh oil change can tip the emmisions a few percent in your favor. I generally time my tune ups every 2 years.

 

B

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schickdog
NPORA Newbie

schickdog

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Posted (edited)

oops. forgot, 88 v6 3.0. and the hydrocarbons were 330ppm @ ~850rpm, not 330rpm. it's an "electo-ignition". is the idle adjust screw the big one behind the throttle linkage? and tighten to increase? been a while since i jacked w idle. also the oil is fresh, maybe 150 miles on it, 10/30. 93 octane gas, otherwise it knocks a lil. and just like every other, it has the exhaust-manifold tick.

 

and thanks for the replies.

Edited by schickdog
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