Cold Start Issue: 320i Manual Facelift

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Rizy247
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Post Mon Jul 27, 2020 1:26 pm

Hi hope you're all well. Facing major start up issues from cold / early mornings.

After cranking on and off for 5-10mins it will fire up with an up and down rough idle and then sort it self out

320i 2 door - G reg Manual

Not sure where to start
1.Air Flow Meter
2.Cold start valve/sensor ? Not sure if I have one
3. Control valve?
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Brianmoooore
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Post Mon Jul 27, 2020 2:00 pm

This could well be an injector problem, leaking fuel into the inlet manifold overnight.
When you park up tonight, stop the engine by removing fuse 11 in the fusebox. This will stop the fuel pump, the engine will continue to run for a few seconds,while it uses up the fuel in the rail, then stall. Switch off the ignition, replace the fuse, and see if this makes any difference when you next start it from cold.
Definitely nothing to do with the brown coolant sensor, and, at this stage, the blue one isn't a major suspect either.
Faulty blue sensor normally gives opposite symptoms to what you describe.
Rizy247
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Post Mon Jul 27, 2020 4:12 pm

Thank you for the reply - I will most definitely give this a try and update accordingly
Rizy247
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Post Mon Jul 27, 2020 4:15 pm

May be worth noting also that the Air Flow Meter has definitely been tampered with , I can see replacement silicone all around it. Hence me thinking maybe it's had this fault in the past and an attempted repair
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Brianmoooore
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Post Mon Jul 27, 2020 6:05 pm

AFM signal is zero at startup. Engine should start and idle almost* normally with the AFM unplugged.

* Not quite normally, because when you disconnect the AFM, you disconnect the inlet air temp. sensor as well.