325 Running rich when cold!

[dannyboy759]

My 325 runs rich when cold, you can smell the fuel and it hesitates on acceleration until you can rev the thing up and clear the cylinders.
It only does this on initial start up and when it hot its fine.
But it never used to do this until the last few 6 or so months it’s had a new blue temp sender but not made much difference, the ecu was chipped and remapped in Germany but ive even reverted back to the standard ECU to see what that’s like but no joy.
It’s not a massive problem, just wondered if anyone had any ideas?

[bodger]

have a look at the jack plug under the inlet manifold, pull back the 2 rubber boots and check for corroded/snapped wires. i had this the wires for the temp senders runs through this socket

[dannyboy759]

Yeah ok, didnt think of that.
Just thinking about it logically even if the temp sender wasnt working and the ecu was putting fuel in surely it wouldnt over fuel on a really cold day because the engine would need the fuel and would run correctly!

[Rosc0PColtrane]

When were the plugs last changed?

[Brianmoooore]

If all else fails, experiment with connecting a resistor across the two wires to the blue sensor. Try something like 4.7k as a starting point.

[dannyboy759]

When were the plugs last changed?

A few thousand ago! ok Brian ill try that, i take it this is a way of finding out what the fault is or is it a quick fix?

[Brianmoooore]

It's a quick fix, but should only be used when all 'real' fault possibilities have been eliminated!
The problem may just be a build up of tolerances of various things, all giving a richer mixer when the engine is cold. The modification is the opposite of the infamous ebay 'power resistor', and fools the ECU into thinking the engine is warmer than it really is.

[Martinaston]

Sounds like leaking injectors if its only doing it at initial startup. Pull fuse 11 to kill the fuel pump/engine when you park up at night, then see if it starts ok in the morning.

[dannyboy759]

The modification is the opposite of the infamous ebay 'power resistor', and fools the ECU into thinking the engine is warmer than it really is.

Yeah understand that so if 4.5 ohms doesnt work where do you go from there?
Up or down?

Sounds like leaking injectors if its only doing it at initial startup. Pull fuse 11 to kill the fuel pump/engine when you park up at night, then see if it starts ok in the morning.

It does it when the engine isnt up to working temp for example if i drive to work then leave the car till lunch and it cools down a little it will do it again its only if it hot it doesnt do it.
So it could be the injectors thinking about it!

[paddyvw]

my 320is is doing this ordered a choke control sensor from c3bmww hopfully it will solve it. if not i will be looking at my afm as it might be open too much when cold