Can anyone please help diagnose myengine management problem?

I have a 54 reg Mondeo 3.0 GhiaX, V6,petrol, 85000 mls.

For several months I have had the errorlight coming on. The predominant errors are: “P0171- System toolean (bank 1)” and “P0174- System too lean (bank 2)”. Thissuggests excess air getting into the inlet manifold. I have checkedfor cracked breather pipes & cleaned the MAF meter I have resetthe light many times but it keeps coming back!

With a warm engine at tick-over, Isprayed butane gas around the inlet manifold and gasket joints to seeif rpm increased to identify where extra air was entering. I didnotice a slight increase when gas was sprayed around the IACV. Iremoved this and re-sealed the gasket but this made no difference!The engine runs well except for an erratic tick-over when hot. Thecar almost seems more lively but average consumption has dropped fromaround 29 to 24 mpg. I took it to a Ford main dealer who kept it for3 days. They charged me £120, and then told me, having checked allof the obvious things they did not know what the problem was.

My confidence in main dealers, if Iever had any, dropped tremendously.

I took it for an MOT, with the lighton, and asked the guys at the MOT Station to advise me if theemissions were unusual, they said there was no problem and it passedthe MOT.

I have noticed that, reading the freezeframe data, the error always occurs around tick-over speed of 850 rpm& once at 1150 rpm. Last weekend, having re-set the light, Idrove non stop to Cornwall and the light did not come on until I wasdriving slowly in city traffic 234 miles later!

My consumption for the journey was 29mpg, previously I would have expected around 34 mpg.



I would be extremely grateful if anyonecould suggest a solution to my problem as I am concerned that, withthe engine ECU probably compensating by running rich, I may damagethe cat's and, of course, I would prefer to reduce my fuelconsumption.




Latest freeze frame data:




Fuel sys 1- CL

Fuel sys 2- 0

Calc load- 19.21%

Coolant temp- 89'C

STFT B1- 8.59%

LTFT B1- 25.00%

STFT B2- 10.15%

LTFT B2- 25.00%

Engine speed- 866.88rpm

Veh speed- 13Km/H




DTC's:




P0171 System too lean (bank 1)

P0174 System too lean (bank 2)

P1131 Lack of HO2S11 switches- sensorindicates lean (see P2195)

P1151 Lack of HO2S21 switches- sensorindicates lean (see P2197)