Amskeptic wrote:whc03grady wrote:When checking for vac leaks with GumOut, how much are we spraying here? I'm reticent to burn down anyone's bus except my own so maybe I had too light a touch, but I didn't notice any change in running and I think I hit all the vac connections.
One intake runner boot was loose enough to turn by hand so we put clamps on it for good measure. It idles near perfectly if you disconnect the little tube from the decel valve. Does this indicate a rich condition? I'm extremely hesitant to mess with the mixture. Oh, hitting the brakes kicks up the idle too, at least for a second.
Anyway, this bus is overdue by at least 1,000 miles for a valve adjustment so I'll be talking Larry through that tomorrow morning. Then we'll look at the points.
Yes, rich due to high elevation, decel valve gave it away.
Be bold! Just NOTE your initial adjustment settings.
For example, with engine off, turn the mixture screw in the AFM clockwise all the way down until it stops. Record how many turns to the prrecise fraction. Now turn it back to where it was.
Since it is rrrich, take another two or three turns counter-clockwise. Test drive.
Now Waterdawg, be CAREFUL with the following FACT . . . .
When you drop below 3,000 feet down on toward sea level, you must be ready to re-richen the mixture. Use the decel small hose as your reference hose.
That now-called Reference Hose also removes the vacuum to the fuel pressure regulator, making it increase fuel pressure. That means you must understand the bias that is introduced when you pull the hose.
The bias is : slightly rich!
You must allow your mixture adjustment to end up "slightly rich" as in a "mild increase in idle" as you take your finger tip off the reference hose. WHEN you put the hose back on the decel valve, the fuel pressure regulator will respond to the vacuum by dropping the fuel pressure, which leans the mixture to "perfect".
Feel free! to turn the black cog wheel teeth inside the AFM cover CLOCKWISE up to six clicks (after you paint an initial setting point!)
to lean it a bit more as necessary if engine is boggy out on the road.
Keep an eye on the CHT gauge, I am glad you have one. Lean is more deadly than rich.
Here is a quicky check anytime.
At a stop, lightly pump the brake pedal quicklyquickly.
If idle drops dramatically - too lean
If idle goes up ridiculously - too rich
If idle drops mildly and recovers when you stop pumping the brake pedal lightly and quicklyquickly - just right
You are HEREBY NOTIFIED that if any drop in power occurs on the road YOU MUST INVESTIGATE IMMEDIATELY, no rationalizations about making it to the next exit.
I'll check in tomorrow, November 14th around 8:00PM . . .
ColinLexusOldManOnTheRoadToMiami