finally fitted the afm but..........

[do-drift-1]

ive finally fitted my afm to my 325i but am now finding that she's running more rich than lean by smell as i didnt receive my bmw manual from egay im not sure how to sort out the air fuel mixture, any advice would be great cheers

[eltel]

on the afm upper body there is a small hex bolt (maybe hidden under a red cap)..turning it clockwise (inwards) richens the mixture and anti-clockwise (outwards) weakens the mixture.. ideally you need to do it whilst connected to an exhaust gas analyser

[do-drift-1]

yeah may have to ask a mate if they have one handy what should the gasses read idealy?

[eltel]

someone will probably correct me but i believe for the e30 it will be

carbon monoxide (CO) - around 1% but definately less than 3.5% for mot.
unburnt fuel hydro carbons (HC) the lower the better

[do-drift-1]

my last mot proved quite difficult as the emissions were through the roof as the throttle body was shot and he reconed the afm was too :S ah well im doint a process of elimination im thinking the timing maybe out as well :S

[TouringTash]

DO NOT TOUCH THE SCREW UNDER THE RED CAP.


Sorry for the capital letters but touch this at your own peril.

[Brianmoooore]

It's safe to adjust the screw under the cap if you're connected up to a gas analyser, but bear in mind that it should not need adjusting, so if it's way out, you should start looking for a fault that's causing the problem, rather than masking the fault by adjustment, as the underlying fault will most likely have other symptoms as well.

[eltel]

i assumed that this was a second hand afm new to you and your car?? in this case surely you'd expect to have to adjust the co slightly as it is running on a different engine and no 2 engines run the same??

adjusting it with an analyser can only be putting it back to standard spec anyway cant it??

[do-drift-1]

just out of interest why shouldnt i touch the afm screw, also what underlying probs would normally cause it to run rich?? s i am waiting on a workshop manual to turn up its been a bit of a mission to trouble shoot things, not too many e30 experts here in wales :S

[do-drift-1]

oh and it was a second hand one cant afford a new afm there rather exorbitant, so trying to fix it atm on a bit of a shoe string budget. . . .

[eltel]

was it running rich before the new afm?? why did you fit a new afm??

rich running can normaly be traced to the blue temp sensor that tells the ecu how warm/cold the engine is.

if it fails it can tell the engine to richen the mixture like keeping the choke out

[eltel]

what part of wales you in??

[Brianmoooore]

On an M20, the usual cause is corrosion and rotted wires in the plug and socket under the inlet manifold, through which the wiring from the blue sensor runs, rather than the sensor itself.

[do-drift-1]

Hmmmm any pics of where these wires are located as i am a bit of a novice when it comes to wiring, some basic knowhow . If theres no pics of this looking into the engine bay which side of the inlet maifold are they located, and how would i go about re-wiring them in etc etc/ sorting them out if it is indeed faulty wiring??. P.S i live in south wales approx 14 miles outside of cardiff, just off the a470, cheers for ure help so far guys

[do-drift-1]

i fitted another afm as the mechanic told me it was more than likely the afm as it was running rich before hand so i fitted one just to see if it'd make much difference if anything it made it run a lil richer :S so i think brianmooore might be more accurate in assuming its the blue sensor or more to the point the wiring. . . . ..

[eltel]

the blue sensor at the top of the thermostat housing should read th following when tested with an ohm meter..

engine cold - 3500 ish ohms
engine hot 0- 350 ish ohms..

the wiring plug in question is beneath the inlet manifold on the passenger side of the car, about halfway up the engine.

it should be attached to a metal bracket, and it is a circular shape, basically the bottom screws up into the top.

[Brianmoooore]

the wiring plug in question is beneath the inlet manifold on the passenger side of the car, about halfway up the engine.

it should be attached to a metal bracket, and it is a circular shape, basically the bottom screws up into the top.

When you find it, you will see that the wire from the bottom part of it turns immediately upwards. The result of this is that any water that gets into the plug and socket collects in the lower rubber boot and can't escape. Eventually it will rot through the temperature sensor wire and the power feed wires to the injectors.

[do-drift-1]

this could also be a possible link to the slight missfire im experiencing hmmmm, my gosh i wished i lived closer to you guys i'd get the beers in ill take all of this on board and have look tomorrow morning cheers gain you two