Saturday, November 20, 2010

How do i adjust the fuel mixture on a mazda mx5 1990 as it is burning too rich?

i have a 1990 mazda mx5 1.6i and it appears to be running rich as i am getting a lot of white smoke out of the exhaust when i accelerate, the power is also down slightly, i did feel it may be the head gasket gone however i am not using water or oil and they are not congeling together so this makes me think it may be fuel, also the smoke does not smell like burnt oil it smells like unburnt fuel mixture? i have change the ignition coil regulator and the spark plugs so i know all four pots are fireing, any suggestions?



Mark.How do i adjust the fuel mixture on a mazda mx5 1990 as it is burning too rich?
There is not much to adjust, the ecm is getting false information.

This can be because the exhaust manifold is cracked, and letting air in. This makes the ECM dump more fuel into the engine.

So look for exhaust leaks, I mention the crack in the exhaust headers because both of my Miata's (90 models) developed cracks at the collector. I replaced them both with OBX headers from e-bay. There was a fitment issue, but they fixed the problem.

But this is not the only place an exhaust leak can develop and such a leak not only lets gas out, but air in.

The other thing to think about is a fuel injector that is not seating and/or a fuel regulator that is not functioning. So check the vacuum hose to the fuel regulator and run some injector cleaner through the fuel system.

The last item (the first to many) is that the O2 sensor is bad. However, I have not had a O2 sensor failure yet. But the items I mentions, I have seen.
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