Need help with a code

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Sep 19, 2010 | 02:37 PM

teamlx88

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Need help with a code

The check engine light came on in my 98 Expy and when I had it scanned it said "lean to bank 2".

What do you guys think? Fuel filter? O2 sensor ? The truck does take a while to start after its been sitting overnight.

As far as the fuel filter goes, what is the part # for the tool to release it? My fuel line tool doesnt seem to fit

Thanks

Sep 19, 2010 | 03:18 PM

fordinlinesix

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From: Azle, TX

Could be an O2 sensor, but I doubt it. Check the exhaust to make sure everything's tight. Clean the MAF sensor. Other than that, it might be a vacuum leak somewhere.

Sep 19, 2010 | 04:39 PM

teamlx88

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Will do. The other thing I noticed was the light comes on after I fill the truck up. If that makes a difference.

Sep 19, 2010 | 05:10 PM

alloro

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Between the lean condition and the slow starting after sitting, I'd say you're looking at replacing the fuel pump. You might want to test the fuel pressure and see if it's up around 55 PSI.

Sep 19, 2010 | 08:01 PM

teamlx88

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Is there a test port or schrader valve somewhere I can tap into?

Sep 19, 2010 | 08:40 PM

pdqford

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From: Central NYS

Quote:

Originally Posted by teamlx88

The check engine light came on in my 98 Expy and when I had it scanned it said "lean to bank 2".

What do you guys think?

P0174 is "System too lean - Bank 2", meaning the PCM is driving Bank 2's fuel injectors rich to to make up for a lean condiction. LTFT (Long Term Fuel Trim) had exceeded ~ 30%.

Since you don't have a P0171 (System too lean - Bank 1) your looking for something that would only effect Bank 2. As inlinesix said, check for an exhaust leak upstream of the Bank 2 oxygen sensor. Perhaps a leaking intake manifold gasket on the bank 2 side. A cracked injector o-ring on bank 2 side. A partially plugged or sluggish bank 2 injector.

If you have a scan tool that will let you look at LTFTs, check bank 1. Its LTFT should be in the +5% to -5% range. If it is up in the +20% range, Bank 1 is also being effected but not enough to trip the P0171 code. In that case you would be looking for things that effect both banks. Like Alloro said, look at fuel pump pressure, fuel supply (filter), EVAP cnaister purge valve leaking, MAF, air leak after MAF, exhaust leaks, EGR vacuum solenoid leaking, etc.

Additionally, if your scan tool can look at the freeze frame data it would give you a clue if it is setting the code at idle or decelleration (prolly vacuum leak) or at highway/load speeds (prolly fuel supply issue).

Sep 20, 2010 | 07:09 PM

teamlx88

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The code sets when I restart the truck after filling it up. When I clear it it takes a long drive (at least 200 miles) and then a refill to set it again. But it doesnt happen everytime.

I want to change the fuel filter but I need a part # or a place where I can get the tool to do it. My fuel line tool doesnt fit.