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post #1 of 3 (permalink) Old 10-13-10, 06:27 AM Thread Starter
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System too lean issue

I have a bit of a problem, and I wondered if anyone here would know what it could be.

My focus is a 2001 SE (2.0L Engine? The smaller crappier one.)

I just recently had my fuel filter changed. Now when I'm idle at an incline (uphill) the engine almost comes to a stall and will stall if idle for too long. The check engine light will eventually come on and with error code: "System too lean (bank 1)"

Here is my obdII read out:
p0171 - system too lean (bank 1)
fuel system: Open loop (system fault)
+17.2 Long term fuel trim (bank 1 & 2)
47.9 psi fuel pressure
MAF sensor .1lb/min
(engine idles between 600-800 RPM)

I *think* I hear a bit of hissing from the back of the engine, but I'm not sure.

Before having the fuel filter changed, I had to have my muffler reattached (it rusted through). I don't know if this could be causing the problem either as the technician somehow caught himself on and unplugged the dataline from the transmission to the system, I wouldn't be surprised he 'bumped' something else.

Keep in mind, I don't have tools/space/time to repair this myself, so I'll have to take it to a shop, I just want to make sure they are repairing the right thing. (and not ^ that shop)

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post #2 of 3 (permalink) Old 10-13-10, 08:18 AM
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Location: Scotland
Posts: 15,732
Re: System too lean issue

Would appear to be drawing air somewhere , worth checking for any air leak on the inlet manifold and also check the vacuum pipes .
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post #3 of 3 (permalink) Old 10-13-10, 08:20 AM
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Location: Oregon
Posts: 10,453
Re: System too lean issue

If there's an exhaust leak near the O2 sensor, it'll read lean. A vacuum leak will do the same from the top. Since it shows that it's been adding fuel (long term fuel trim), it's been there for awhile. A shop should be able to find it fairly fast with enough explanation from you.

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