Hello all.

I just adjusted valves, upgraded to pencil type plugs, changed fuel filters, but I am still getting a slight miss/rough idle at cold start up (sitting overnight.) My idle control knob is turned fully CW when this happens. It fires quickly after the first glow cycle is complete but runs rough until I accelerate a bit. Do these cars need a bit of a boost by the idle knob on cold(cool) starts or not?

Thanks again.

Turning the idle knob CCW increases idle speed

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

That is the whole reason for the existance of the inside idle knob. Increase idle for cold starts especially in cold weather or lessened compression.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

I understand the purpose of the idle knob and how it works, but is it a norm to have it somewhere 'in the middle of travel' for smooth idle when it's like 45-50 degrees outside on a cold engine, or is it supposed to run fine completely CW at these temps?

Open it up for the start up and then close it down as the engine warms up. Should run at or nearly closed once engine is up to operating temp (~80 C). Mid range sounds pretty normal for cold engine idle, as that is what it is there to compensate for.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

I start my 240D with the idle knob completely CCW, then within 3 miles of driving im fighting the motor with the brakes trying to stop at a red light and turn it all the way CW.

In the weather we've had for the past 2-3 weeks here in PA, I haven't needed to touch the idle knob starting it at 6 in the morning.

BIG variables in the knob are:
- a maladjusted idle cable adjustment
- throttle linkage molestation
- compression, glow plugs, etc.
- just a thought, but oil viscosity?

You would benefit from the "Afterglow" mod. Search "Purple wire snip".

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