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E30 with a Motronic 1.3 running rich

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Bluestone City View Drop Down
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    Posted: 06-August-2012 at 11:54
The engine in my E30 320i appears to be running rich with heavy fuel consumption. A CO check hasn't been carried out yet but a small amount of smoke is visible at idle which becomes a noticeable cloud when the engine is revved to 2000 rpm.

I have checked the following things:

Air filter - nearly new.
Air flow meter flap moves smoothly.
Spark plugs - nearly new but now blackened.
Throttle assembly - cleaned with carb cleaner (I do this every year) and the throttle position switch works.
No noticeable air leaks. The idle speed is smooth.
Coolant temperature sensor resistance approx 200 ohms when hot. I have tried substituting for a 220 ohm resistor with not noticeable effects.
I have screwed out the air screw in the air flow meter assembly to lean off the mixture.
I have performed several Redex treatments so it's unlikely that the injectors are clogged.

I performed a stomp test with a bulb connected to pin 15 of the ECU (American E30s have this Check Engine light on the dashboard) and it flashes 1444 every time. I have even simulated faults and the ECU outputs the correct fault codes so this feature works.

Does it look like the ECU is faulty but the diagnostics isn't picking it up?

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Andrew Rolland View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Andrew Rolland Quote  Post ReplyReply Direct Link To This Post Posted: 06-August-2012 at 12:09
Some form of fuel injector fault?
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Bluestone City View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bluestone City Quote  Post ReplyReply Direct Link To This Post Posted: 06-August-2012 at 12:52
All 6 spark plugs are equally blackened so an individual fuel injector is not faulty. A leaky fuel injector would result in a single spark plug encrusted with carbon.

I was verbally informed that the fuel pressure regulator was defective about 6 weeks ago so a new one was installed but it hasn't made too much difference.

I have also tried 'resetting' the ECU by disconnecting the battery in case it has a CPU lockup but that doesn't seem to cure the fault.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote E30 ONLY Quote  Post ReplyReply Direct Link To This Post Posted: 18-February-2016 at 23:22
Hi Bluestone,

Check for a vacuum leak to the fuel pressure regulator.  Other than that, possible AFM fault ?

Cheers,

Dave.
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thepits View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thepits Quote  Post ReplyReply Direct Link To This Post Posted: 19-February-2016 at 13:13
hello again Dave, good suggestion, but as the last time Bluestone City visited us was back in August 2012.....
Cats know your every thought.

But don't care.
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