E30 Zone

My cars(m20B25) running rich, exhaust fumes are petrol smell and light grey smoke out exhaust, not sure if its water vapour or not.

Ive tested the blue sensor at the ECU pin 45 and ground and when cold is 2.7ohms. Ive yet to test hot at the ECU but at the blue sensor it was a higher reading.

Idles fine, runs well otherwise, 300 motorway miles for 38liters means 35mpg. Around town its 200miles for 40ish liters, 22mpg approx.

Any ideas folks?

2.7 ohms is way too low for the Blue Temp sensor. Proper testing procedure and results here:

http://www.e30zone.net/e30zonewiki/inde ... ug#Testing

Grrrmachine wrote:2.7 ohms is way too low for the Blue Temp sensor. Proper testing procedure and results here:

http://www.e30zone.net/e30zonewiki/inde ... ug#Testing

I think there may be a 'k' missing from that reading!
In any case, it's the hot reading that's more important.

correct Brian 2700ohms.

Should get a hot reading over the next few days but presuming its fine is there anything else?

Sanchez wrote:My cars(m20B25) running rich, exhaust fumes are petrol smell and light grey smoke out exhaust, not sure if its water vapour or not.

Ive tested the blue sensor at the ECU pin 45 and ground and when cold is 2.7ohms. Ive yet to test hot at the ECU but at the blue sensor it was a higher reading.

Idles fine, runs well otherwise, 300 motorway miles for 38liters means 35mpg. Around town its 200miles for 40ish liters, 22mpg approx.

Any ideas folks?

Your mpg is healthy so this is likely an idle fuelling issue, I take it the exhaust smells rich at idle. It could be your TPS not registering the idle position or more likely your AFM that has been adjusted when it shouldn't have been. as your AFM lost it's small round plug on the top revealing an allen key adjustment underneath?

Does your car have a lambda sensor?

No Lambda, and the AFM has a red grommet on the top.

I think the adjusting screw still has its grommet on as well.

im goning to resurect this and ask if there is any way to "set up" the afm adjustment, my car stinks with windows open, closed with blowers on its loverly!!! the ex manifold is ok and there is no apparent holes in the exhaust?!?!

Maybe you have a fuel leak rather than overfueling.

i've ruled fuel leak out as it smells of exhaust not petrol, + ive just had tank and all lines replaced

You can as far as I understand alter the idle mix (rich/lean) with the AFM hex screw. You do need an exhaust analyser however as an incorrect mix is bad for you engine and an MoT fail.

Are you sure no one hasn't already tampered with this screw?

As stated check the mixture with an exhaust analyser and adjust the screw.
If the reading is way out then a previous owner may have opened the AFM and moved the position of the circular spring....moving it clockwise weakens the mixture and counter clockwise enriches it.
This should not normally done as it is set up at the factory but mark the position of the spring and move it by one notch if really needed!

I wouldn't recommend doing this, it will bugger up your idle speed. The AFM was not designed to be opened and tampered with, its a very sensitive, calibrated device.!

I had the very same issue as you when I got my 325i. Ok gas mileage, rich idle exhaust, it stank. Especially on a cold start, wow it almost made me barf...

I changed my spark plugs, distributor cap and rotor arm. My idle speed went up from 500rpm to 700 rpm, I got around 4 mpg more and no more rich idle fuel smell. I'd explore these options first if your AFM hasn't been tampered with.