Running Rich

[Gus 5]

im fairly sure my m20 is running a little rich. smells quite fuelly when idling esp when cold, and unburnt fuel (i think) goes through exhaust to crackle and pop. which as cool as is sounds, im sure it means its not running right. seems normal otherwise. takes a while to start sometimes too.

currently im thinking it may be the dizzy...a new cap and rotor is probably due. any other ideas?

[Guest Spargo]

Me also, will be watching this thread.

[nz320i 0]

how much for dizzy cap and rotor i need one too

also how hard is it to change the thermostat

[Gus 5]

somewhere around 150ish...thermostat easy...3bolts and 5 mins

[jochen 4]

If your engine is at normal operating temperature but still running rich, and if you have an electronic controled motor (I'm not familiar with the M20) then check your motor temp sensor

I had a VW Golf where the wire to the temp sensor for the motor electronics broke. This is separate to the temp gauge sensor. So temp gauge still read OK but motor ran rich.

The motor electronics read this as a very cold engine and increased the mixture to the point that the plugs foulled and black smoke came out the exhaust.

So worth a check

Jochen

[Carl 3]

Quite frankly i'm surprised you haven't just opened the AFM up a little bit

[Guest Andrew]

Chuck it on the emissions machine at Bavarian and adjust the AFM n00b.

[drifty325i 0]

Could be the blue temp sender thats my guess

[nz320i 0]

where is the temp sensor and what 3 bolts do i undo for thermostat ?! cheers

[gmccormack 0]

Temp sensor would be my first guess too. It's not a real sensor as such but a switch that trips at 70 degrees, earth out the temp sensor wire and see if that helps.

The screw on the AFM is only for idle mixture adjustment, you could play with it if the problem is only occuring at idle but otherwise I'd leave it alone.

Is it running rich WOT or no load/light throttle/overrun??. If it's running OK when you give it the jandal, but rich on light throttle it could be the AFM flap is not returning fully under spring tension. Clean it out and make sure the flap is moving smoothly, without any binding.

[Silver Fox 43]

Hey Graeme, could a M40 have the same problem if smelling of fuel at all speeds, can't drive with the window open, stinks too much.

[nz320i 0]

to add to this thermostat stuff-

Got one today $71 incl (trade discount) from dealer (cheers guys!)

Prices for rotor and dizzy cap

Cap $70

Rotor $70

engine temp sensor and coolant sensor were both about $90

Holllaa

Edited September 19, 2006 by nz320i

[drifty325i 0]

to add to this thermostat stuff-

Got one today $71 incl (trade discount) from dealer (cheers guys!)

Prices for rotor and dizzy cap

Cap $70

Rotor $70

engine temp sensor and coolant sensor were both about $90

Holllaa

Bizzzzzzzz dam i hate money sometimes

[gmccormack 0]

Hey Graeme, could a M40 have the same problem if smelling of fuel at all speeds, can't drive with the window open, stinks too much.

The fuel lines that run under the manifold are prone to cracking in M40's. If the engine is otherwise running well and the only problem you're having is the smell of fuel I would suspect them before anything else. Cleaning and checking that the AFM is moving freely is worth doing too in any case.