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Joined: Dec 2001
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I've searched on this and turned up a BUTTLOAD of data. Here's the deal:
This weekend after getting my oil changed and replacing my headlamp assemblies (which involved removing the battery, thus resetting my PCM) I suddenly found myself with a CEL. The codes are the P0171 and P0174 (too lean on both banks).
After researching this, I've decided it would be really freaky to loose 2 O2 sensors at once, and I just cleaned my UIM about 8000 miles ago and haven't had a vacuum leak at all since then (new gaskets, the works, except I didnt' replace the fuel pressure regulator). So I'm figuring either it's a dirty MAF, OR it's a problem with my fuel delivery system.
I also wanted to mention that I'm getting GREAT gas mileage with the CEL, and the engine runs cooler. In fact, she runs just below the N in NORMAL. But I do seem to notice a slight loss of power at WOT, but it may just be a plecebo effect.
I'm going to try cleaning my MAF with electronics cleaner today, but I'm wondering if it's that Fuel Pressure Regulator I never changed or possibly the fuel pump? I mean the car DOES have 104k miles on it :/
How do I test for proper fuel pressure?
Last edited by rkneeshaw; 05/04/03 01:29 PM.
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Joined: May 2003
Posts: 131
CEG\'er
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CEG\'er
Joined: May 2003
Posts: 131 |
have you tried clearing the code to see if it was a fluke?to test the fuel pressure youll need a fuel pressure gauge and adapter.
(2)1994 mustang GTs 2001 gt convertible loaded.www.haywoodspeed.com
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Joined: Dec 2001
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Hard-core CEG\'er
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Hard-core CEG\'er
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I stopped at an autozone and had them clear the codes. It came back a couple hours later.
Can I get one of the guages and adapters at any autoparts store?
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Joined: Sep 2000
Posts: 449
CEG\'er
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CEG\'er
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SVTCANUK has had this problem and got rid of it by tourquing the UIM to the upper end of the spec range. We just did mine yesterday and I can't recall now what it was (around 95 inch pounds IIRC) ... care to chime in here Rob?
98.5 SVT now gone ... new wheels = 2005 330i
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Joined: May 2003
Posts: 131
CEG\'er
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CEG\'er
Joined: May 2003
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10nm or 89 in/lb.that was from fords QC dealer online shop manuals.
Last edited by RayL5480; 05/04/03 02:05 PM.
(2)1994 mustang GTs 2001 gt convertible loaded.www.haywoodspeed.com
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Joined: Jan 2002
Posts: 753
Veteran CEG\'er
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Veteran CEG\'er
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Does the cel come on intermittently. Before changing my o2 sensors at 100,000 miles, I would get a cel usually on the highway. It would go on and off every minute or so. On my obd 1 system it was codes 172 and 176 if I remember correctly. After I changed the front sensor I did not get any cel's. But I changed the rear one anyway, major pita.
About the fuel regulator, as far as I know if it is bad the main problem you will get is surging.
And finally, the o2 sensors would not cause a loss of power at wot because the engine doesnt't use the reading from them at wot.
Dueling Duratecs
'95 SE V6 MTX 0 Mods
'04 Mazda6 S Wagon
'03 Kawasaki Z1000
But thus do I counsel you, my friends: distrust all in whom the impulse to punish is powerful!
Friedrich Nietzsche
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Joined: Dec 2001
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Hard-core CEG\'er
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Once the CEL comes on, it stays on till I either clear the codes with an OBD-II scanner tool or by resetting the PCM.
It's probably not hte fuel pressure regulator then becuase there's no surging. Could it be a failing fuel pump?
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Joined: Jun 2002
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Hard-core CEG'er
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Hard-core CEG'er
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I had the exact same problem last week. The same codes, the same great gas milage and the same cool running engine. You can search for my posts. I solved my problem by re-torquing my UIM/LIM bolts to the max 108 inlbs (previously 72 inlbs) and I also replaced all the small hoses on the PCV valve and put a clamp around the large one on the bottom for a better seal. I don't know which of these fixed the problem because they were done at the same time but it is a place for you to start looking. BTW when you fix the problem the engine runs warmer and the great milage goes away .
99 CSVT Green/Tan
# 84 of 2760
Built on Wednesday, September 30, 1998
15.376 @ 92.00 MPH Stock
75,000Km
96 Contour GL
2.5L V6 ATX 170,000Km
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Joined: Dec 2001
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Hard-core CEG\'er
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Well I went out and bought myself a torque wrench and torqued the bolts all down. I just guessed before, looks like I actually over-torqued them though. All the bolts where just over 100in-lbs already. Looks like I'll have to look elsewhere for the cause of this problem If it was the fuel pump, I would get surging right? Or could the fuel pump be starting to fail and not push enough fuel to the injectors?
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Joined: Jun 2002
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Hard-core CEG'er
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Did you check all the hoses for an air leak? I would suspect an air leak before a fuel problem. Spray some carb cleaner around the UIM/LIM as well as anything that runs into the UIM. If you have an air leak the car will hesitate when the carb cleaner is sucked in.
99 CSVT Green/Tan
# 84 of 2760
Built on Wednesday, September 30, 1998
15.376 @ 92.00 MPH Stock
75,000Km
96 Contour GL
2.5L V6 ATX 170,000Km
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