m42 running too rich need some referrals to someone who can tune it

[ma.jomaa]

Hello,

I have a 1975 2002 that has an m42 swap, since day one the car was running way too rich, the fumes are unbearable, I'm averaging 24-25mpg with regular driving conditions. I'm looking for advice on how or who can tune the AFR for me in the Los angeles area, any input is greatly appreciated.

[bmwman91]

Assuming that you got everything connected properly and are running a complete stock ECU setup, it should not run rich. It should maintain stoichiometric (14.7:1) air-fuel ratio except on cold starts (it will smell gassy until the temp needle gets past the 1/4 mark) and at WOT. Assuming that you are using the stock ECU and harness, are you also running the O2 sensor? If so, then something is wrong and it'd be good to figure out what before going to a tuner to try to work around whatever is going on. Also, is there a catalytic converter on the car?

[ma.jomaa]

Assuming that you got everything connected properly and are running a complete stock ECU setup, it should not run rich. It should maintain stoichiometric (14.7:1) air-fuel ratio except on cold starts (it will smell gassy until the temp needle gets past the 1/4 mark) and at WOT. Assuming that you are using the stock ECU and harness, are you also running the O2 sensor? If so, then something is wrong and it'd be good to figure out what before going to a tuner to try to work around whatever is going on. Also, is there a catalytic converter on the car?

Thanks for the reply, I'm using stock ECU, with stock m42 harness, however the electric fan is running all the time so that might be keeping the engine below operating temps, \

What is the operating temperature of the m42?

I am running the 02 sensor but don't know if it's bad or not, how do i check for that?

lastly there is no catalytic converter, header's down to midsection muffler and to rear muffler. I'd rather stay away from tuners as I'd like to save my self some money, your input is greatly appreciated.

[Dj Buttchug]

no cat = awesome fuel vapors op. 25-30 ish average is normal mileage with m42





Opie, you likely have no issues. Youve been huffin dem hydrocarbons bruhhh

[ma.jomaa]

I'll get a Wideband AFR gauge to check my AFR, I've had other cars without cat and the fumes were not as bad as this one.

[bmwman91]

Thanks for the reply, I'm using stock ECU, with stock m42 harness, however the electric fan is running all the time so that might be keeping the engine below operating temps, \

What is the operating temperature of the m42?

I am running the 02 sensor but don't know if it's bad or not, how do i check for that?

lastly there is no catalytic converter, header's down to midsection muffler and to rear muffler. I'd rather stay away from tuners as I'd like to save my self some money, your input is greatly appreciated.

The M42 uses an 88°C thermostat, and at least on an E30 instrument cluster, the temperature needle will nominally point at the middle marker or just below. If the electric fan is on at all times, then something is probably wired wrong and it may be keeping your engine too cool, which will definitely lead to rich running. I accidentally put an 80°C thermostat in back in 2003 or so and it ran pretty rich all the time until I put the proper one in.

If you are still running rich, then something is up. Good call on getting a WBO2 in there to test things out.

[RedReplicant]

Time to test your o2 sensor.

[ma.jomaa]

The M42 uses an 88°C thermostat, and at least on an E30 instrument cluster, the temperature needle will nominally point at the middle marker or just below. If the electric fan is on at all times, then something is probably wired wrong and it may be keeping your engine too cool, which will definitely lead to rich running. I accidentally put an 80°C thermostat in back in 2003 or so and it ran pretty rich all the time until I put the proper one in.

If you are still running rich, then something is up. Good call on getting a WBO2 in there to test things out.

Thank you for the input.

Time to test your o2 sensor.

how do i test it?

[Wild Ride]

Vacuum leaks in the "mess under the intake" will also cause a rich running condition.


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[AndrewBird]

If you are suing all stock wiring, you should be able to pull codes from the ECU using the stomp test. Do you have the check engine light hooked up?

Here is a how to on the stomp test:

http://www.pelicanparts.com/bmw/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm

The engine temperature sensor for the ECU could be bad, cause it to run rich all the time. A bad O2 sensor will do the same. Are you sure you are running the stock injectors?