Idle question (KE-jet as it happens)
Discussion
Hi,
Couple of questions about engine idle in general.
I have a cossie Merc, which starts fine when cold (sometimes takes 1 or 2 seconds of cranking in fact).
When warmed, it runs fine, although can occasionally stall if you take your foot off the clutch, say pulling up to a junction. The warmer it gets, the worse this seems. In traffic (engine 100-105 degrees) it barely holds idle at all, dropping to 500-400 and then stalling, every time.
Why is this? Why would idle be worse when hot? It has an electrically operated idle control valve (a valve letting air into the engine, bypassing the throttle). Should this be preventing this, or is it just designed for cold engine running? I.E. Shouldn't the engine idle fine when hot, even if this idle control valve is broken?
Couple of questions about engine idle in general.
I have a cossie Merc, which starts fine when cold (sometimes takes 1 or 2 seconds of cranking in fact).
When warmed, it runs fine, although can occasionally stall if you take your foot off the clutch, say pulling up to a junction. The warmer it gets, the worse this seems. In traffic (engine 100-105 degrees) it barely holds idle at all, dropping to 500-400 and then stalling, every time.
Why is this? Why would idle be worse when hot? It has an electrically operated idle control valve (a valve letting air into the engine, bypassing the throttle). Should this be preventing this, or is it just designed for cold engine running? I.E. Shouldn't the engine idle fine when hot, even if this idle control valve is broken?
Also, Check the air bypass screw for the base idle adjustment, this will be on the throttle body and the throttle butterfly. These ate prone to getting fouled up with deposits from the crankcase breather system.
Remove the air intake hose from the throttle body.
Screw the air bypass screw all the way in counting the turns as you go and then remove.
Use some carb cleaner and non-linting cloth and give the throttle body, butterfly, particularly the edges of the butterfly and the area of the body where it closes on to, a good going over.
Spray the cleaner down the air bypass screw passages and clean the screw end.
Rebuild it all adjusting the air bypass screw to the same number of turns fro closed as before.
Warm the engine up and readjust the idle speed to suit.
HTH
Steve
Remove the air intake hose from the throttle body.
Screw the air bypass screw all the way in counting the turns as you go and then remove.
Use some carb cleaner and non-linting cloth and give the throttle body, butterfly, particularly the edges of the butterfly and the area of the body where it closes on to, a good going over.
Spray the cleaner down the air bypass screw passages and clean the screw end.
Rebuild it all adjusting the air bypass screw to the same number of turns fro closed as before.
Warm the engine up and readjust the idle speed to suit.
HTH
Steve
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff