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Topic: P0171 & P0174 (Read 2309 times) |
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Dave2302
Senior Member
2006 Mercedes S55 AMG, Retired Barefoot Waterskier
 
Posts: 1119
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P0171 & P0174
« on: May 14th, 2007, 6:15pm » |
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Hi all,
1996 24V Cossie Ultima Estate.
Has had new pre cat Lambda's, new engine loom, plugs and HT leads all within past year, and has been running ok after these repairs.
Intermittant sluggishness is now becoming more and more prevalent. It sometimes feels like its only firing on 4 - 5 cylinders but I really dont think its actually misfiring, its more of a general lack of punch. Seems better above 3000 revs, but not as it should above 5000 revs.
Getting System too lean Bank 1 and Bank 2 codes P0171 and P0174. No other codes present.
AFAIK there is no obvious air leaks. 
What is this telling me ? (apart from the blooming obvious) 
What I mean is where should I be looking ? 
Perhaps Fuel Pressure Reg ? , EGR ? , I dont want to change bits blindly, cos that gets expensive so can anyone help ??
Regards Dave
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Dave "The 'ol Bear" ex Footer !
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scorpio_man
Administrator
Ford Kuga awd
Posts: 5654
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Re: P0171 & P0174
« Reply #1 on: May 14th, 2007, 8:09pm » |
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hi there
to me, it sounds like it's running rich, pointing to the fpr.
what % are the ltfts?
a take it the lambda are both switching healthily?
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Dave2302
Senior Member
2006 Mercedes S55 AMG, Retired Barefoot Waterskier
Posts: 1119
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Re: P0171 & P0174
« Reply #2 on: May 15th, 2007, 9:54am » |
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Hi,
Thanks for reply. 
The bank 2 after cat Lambda doesn't move as much as the other 3, stays between 290 - 330 mv, but the other 3 are anywhere between 30 - 700 mv.
(Am assuming the after cat Lambda's don't affect the running which is why I haven't changed them.)
I reset it all yesterday, so I will take it for a 10 mile drive and report back fuel trims, and other data after a drive.
TIA,
Regards Dave
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Dave "The 'ol Bear" ex Footer !
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Dave2302
Senior Member
2006 Mercedes S55 AMG, Retired Barefoot Waterskier
Posts: 1119
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Re: P0171 & P0174
« Reply #3 on: May 15th, 2007, 12:56pm » |
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Hi again,
Right, have pages of data, but will post what I think is most important, if there is anything else please ask cos I recorded all of it for posterity
Sorry if I've posted too much, but I wanted to get a broad picture of whats happening
First, stone cold Ignition On but engine NOT running:-
Battery 12.3 v
TPS @idle............................................ 0.92 v
TPS @ WOT.........................................4.78v
(smooth rise all the way through)
Intake Air Temp Sensor.......10 deg C........ 3.5 v
Coolant Temp Sensor..........10 deg C.........3.53v
O2 Sensor Heaters............... ON
O2 Sensor Bank1 Before Cat............90mv (farly steady)
O2 Sensor Bank1 After Cat...............77mv (fairly steady)
O2 Sensor Bank2 Before Cat............72mv (fairly steady)
O2 Sensor Bank2 After Cat...............77mv (fairly steady)
LT Mixture Adaptation 1 ............... -22%
LT Mixture Adaptation 2 ............... -21%
ST Mixture Adaptation 1 ............... 0%
ST Mixture Adaptation 2 ............... 0%
(Remember I reset it last night and haven't driven it since).......
Then started engine and got the following with a cold engine idling:-
Battery 13.9 v
Injection Time 1.................4.5 ms
Injection Time 2.................4.4 ms
O2 Sensor Bank1 Before Cat...825mv (switching steady)
O2 Sensor Bank1 After Cat...105mv (switching steady)
O2 Sensor Bank2 Before Cat...895mv (switching steady)
O2 Sensor Bank2 After Cat.... 78mv (switching steady)
LT Mixture Adaptation 1............1%
LT Mixture Adaptation 2............1%
ST Mixture Adaptation 1............6%
ST Mixture Adaptation 2............6%
O2 Sensor Heaters.................OFF
Coolant and Inlet Air Temp figures rising smoothly.....
After a 15 mile run motorway and town driving, the following were taken with hot engine Idling :-
Battery 13.6 v
Intake Air Temp Sensor......51 deg C.....1.58 v
Coolant Temp Sensor.........91 deg C.....0.60 v
Injection Time 1.....................2.8 ms
Injection Time 2.....................2.9 ms
O2 Sensor Bank1 BC....32 to 890 mv (switching rapidly)
O2 Sensor Bank1 AC....110 to 725 mv (switching rapidly)
O2 Sensor Bank2 BC....20 to 805 mv (switching rapidly)
O2 Sensor Bank2 AC....44 to 687 mv (switching rapidly)
LT Mixture Adaptation 1............. - 16%
LT Mixture Adaptation 2............. - 17%
ST Mixture Adaptation 1............. 2%
ST Mixture Adaptation 2............. 2%
O2 Sensor Heaters.................... OFF
During the test drive, the car drove pretty well, felt slightly flat at around 120 MPH, but otherwise OK, fault codes have not come back yet. (I hate intermittant faults ) However, chances are next time I drive it it will run like a 3 legged dog  and the codes will re-appear. 
Any Ideas as to the cause will be gratefully received
Many TIA for help and input.
Regards Dave
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Dave "The 'ol Bear" ex Footer !
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scorpio_man
Administrator
Ford Kuga awd
Posts: 5654
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Re: P0171 & P0174
« Reply #4 on: May 19th, 2007, 7:59am » |
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hi dave
pm sent.
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arand
Newbie
I'm a YaBB newbie!
Posts: 4
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Re: P0171 & P0174
« Reply #5 on: Aug 16th, 2007, 1:33pm » |
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hi!
I have 2.0 DOCH estate and same P0171 error on obd. As OP described, on revs below 3k the engine seems sluggish, over 3k it starts to show some power.
A few month ago I changed pre cat lambda. New plugs and HT leads are on my todo list right on top
A friend, who lend me obd scanner told me to check fuel filters and fule pump.
What dou you suggest?
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