Black smoke and engine codes
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Elder User
Joined: Mar 2003
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From: Medford, OR
Black smoke and engine codes
I replaced my MLPS last week and that eliminated the hard shifting along with one of the codes I was throwing. My check engine light still comes on after driving for 10 minutes or so. With the KOER test I am getting a code 173: HEGO (HO2S) Sensor Fault/Rich. The only continuous codes I am pulling are the same 173 code, and a 628: Excessive Converter Clutch Slippage. The truck does smell like it is running rich. I replaced the o2 sensor about 7 months ago, but it never cleared the code. Besides running rich the only noticeable problems with the truck, which may or may not be related, are a hesitation at light throttle and a recently developed problem where black smoke billows out of my exhaust if I rev it up while in park or neutral. I don't notice any smoke when driving. I have heard that could possibly be the fuel pressure regulator? I really appreciate any input on what could be causing these problems! Thanks.
Aaron
Aaron
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Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
replace the o2 sensors , give motor a tune up with new wires,plugs, cap and rotor. timing should be at 8-10*btdc with spout disconnected. could also be a bad coil. i would get your fuel pressure checked to. after you fix these things its important to disconnect battery for 15mins , reconnect and drive for 45mins in various conditions.
stop an go, some wot, and steady 55-65 mph driving , this way the computer can relearn and make proper changes. also change air filter to if that hasnt been done in awhile.
stop an go, some wot, and steady 55-65 mph driving , this way the computer can relearn and make proper changes. also change air filter to if that hasnt been done in awhile.
Logistics Pro
Joined: Jan 2002
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From: GANS
I'll check out the other components b4 I'd replace the O2 sensor again. It the computer can't lean out the mixture, it will fault saying the O2 sensor is rich, indicating that the O2 sensor is bad, but it is actually reading correctly, and another component has failed.
I'd definatly try clear the cpu first, it [the code] might still be lingering from when you changed the sensor b4.
I'd definatly try clear the cpu first, it [the code] might still be lingering from when you changed the sensor b4.
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Elder User
Joined: Mar 2003
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From: Medford, OR
I bought a guage and am looking at my Haynes manual. Which test do I need to run? They list over and underpressure tests. Do I need to disconnect the fuel line or is this something I can just hook up while it's running? Thanks.
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Joined: Jun 2004
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black smoke
first what years is the truck ? if it is a 5.0 or a 5.8 v8 the fuel psi. should be around 41 to47 psi on it....if it is not that high then you might want to chech you'r fuel filter. and did you replace you map sens when you done all the other stuff?
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Lead Driver
Joined: Feb 2003
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From: Oak Harbor, OH
There is a black cap on a schrader valve under the hood, make sure you have a HIGH pressure fuel pressure tester, it will screw onto said valve (looks like a big tire valve stem) you SHOULD have ~40lbs with the enging idling, and vacuum supplied to the FPR, it should jump to ~50lbs when you remove the vacuum line. If it's at a high pressure then the regulator is bad, if it's low it could be the FPR, fuel filter, or pump.
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Thread Starter
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Elder User
Joined: Mar 2003
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From: Medford, OR
I tested the fuel pressure today and idling it is running at ~90psi and drops to about 85 when I give it gas. Does that sound like it would more than likely be the regulator? Thanks.
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Elder User
Joined: Mar 2003
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From: Medford, OR
Thanks for the help. I will replace that tomorrow and see where that gets me. Any special instructions for replacing that or is it spelled out pretty easily in my Haynes manual? Thanks.
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Elder User
Joined: Mar 2003
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From: Medford, OR
That FPR is a big pain in the butt. Is there some trick to getting at those screws from the bottom because I have been fighting it for about 2 hours and have only managed to remove 2 screws. It seems like there is no way to get to them unless you remove the fuel rail, which would be a lot more work. Any tips would be appreciated. Thanks.
Posting Guru
Joined: Apr 2002
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From: Greenwood In. USA
I used 2 different allen wrenches one long one without the bend and a std one to tighten up. Take your time. Its a pain but do able. Do a search there are tons of posts on here on FPR changeout
Good luck
Good luck
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Elder User
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From: Medford, OR
Thanks for the advice, Gasman. I was using a torx bit on a ratchet so that may be why it has been so difficult. I didn't realize they were allen bolts since you can't see the stupid things. An allen wrench would be WAY easier to get down in there. I actually went so far as to cut the end off one of my old ratchets with an angle grinder to give me room to get it in there. Do you know what size allen wrench I would need or does the size vary? I will need to stop in and buy some allen wrenches on my way home from work. Thanks.
Last edited by Wakeboarder141; Jul 28, 2004 at 06:05 PM.