runs very rich mixture, air filter help

[michael24m]

it runs very rich and i get high fuel consumption, 12litres/100km(highway) . the exhaust gases smell like gasoline vapours.
i noticed there is a turn knob on the airfilter housing. what's the corect adjustment for that? i guess it has something to do with that.
help needed, thanks!

[michael24m]

oh, i forgot. the car is a 320i engine m20

[Turbo-Brown]

Shouldn't be any adjustments on the air filter.

Might just be a very dirty air filter perhaps?

[Martinaston]

Check the condition of the spark plugs, they should tell you if it's running too rich.
The screw on the air flow meter is turned clockwise to enrich the mixture and anti-clockwise to lean it out, but should only be done with a CO meter up the pipe (give the MOT station a drink to do it)

You can do it yourself but if you run it too lean it can run too hot and ruin the valves.

If that doesn't cure it then the injectors are shagged.

[hoshy]

Doesn't that only control the idle mixture and have very little effect elsewhere?

[Andy_magic]

The CO adjustment will only affect the CO at idle, the actual running of the engine mixture is controlled by the ECU which gets information from the engine via the blue temperature sensor on motronic equiped cars.

The test to carry out is to get the engine up to normal operating temperature then unplug the blue temp sensor, the engine note should change and the car should run rougher as the ECU thinks the engine is stone cold and richens the mixture up.

If there in no change in the engine note suspect the blue temp sensor, I think they are Ԛ£20 from the dealers. I have also found a few cars with dodgy wiring to the ECU from this sensor, mainly in the injector/sensor wiring loom under the inlet manifold, the contacts here can corrode and cause no signal to reach the ECU causing the same running conditions as a duff sensor.

Heres a link to a guide I wrote on sorting the M20 motronic engine management out with simple tools etc. Hope it helps

http://www.e30zone.co.uk/modules.php?na ... ning+rough

Oh yes, make sure the air cleaner is good too.!

[michael24m]

thanks all for the advice! i'm getting into this tomorrow, it seems like i have a bit of stuff to check out in order to sort this.

A question to Andy_magic, where is the blue temp sensor located?

thanks

[Andy_magic]

Glad to be of help mate, the blue temp sensor is on the thermostat housing at the front of the engine, it's a bit fiddly to get out though, I normally use a cranked end 22mm (I think) spanner to get these out.

Any questions, feel free to ask.

[michael24m]

thanks mate! i had a feeling that was the one, with the brown and blue leads, right on the thermostat housing.

[michael24m]

oh yeah, and if remove the blue wire conection to this, that will also affect the engine temp gauge leaving the needle all the way to the right. right?

[Andy_magic]

The brown temp sensor deal with the gauge, if you unplug it the gauge will drop to fully cold.

Out of interest, where does the temp gauge sit on your car after 10 minutes of driving, it should sit about the half way mark, it's possible if the car is overcooling the water temperature will be very low causing a rich mixture.

My car sits just under half way and if left idling for 30 minutes climbs to just over half way.

[michael24m]

mine does exactly the same, while driving just below the mid line and left idling climbs just 1 mm above the mid line.

[Andy_magic]

Thats good then, one less thing to worry about.

[michael24m]

thanks mate! i'll be sorting this out tomorrow, will let you know how things are going along.


i'd buy you a beer but i'm from the other side of europe

[michael24m]

eng pic with parts numbered is at this url:

http://24rsk.thor.prohosting.com/M20Engine/tempspic.htm


I was advised that this is the L-Tronic injection system.


1 - Brown white lead, measurements shows +12V voltage, removed whiled engine running at idle, no noticeable change

2 - Red White lead, same but -12V, still no noticable change.

3 - Single lead - in dash Temp gauge, when removed the temp gauge needle goes dead.

4 - Brown lead - not connected, seems to be the earth connection, no role whatsoever

5 - 2 Lead plug, removed while engine running, no noticeable change, measurements show no voltage running trough it. What role does this plug have? it's present on all the older L-tronic injection systems, the M30 engine seems to have it too in the same location.

Where might be the temp sensor that informs the ecu of the temp?
Where is the thermotime switch? are this one and the same sensor?[/url]

[tonyr]

ive got a similer problem with my 89 325 m20, when cold it ides sound, when it warms up it always has a hesitation when i give it some gas ,note the choke seems to come off quick aswell,any ideas?