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)

 

I have had this problem a couple of times, turned out to be the timing had moved, i would check that for a start?

 

The mixture seems to be very lean, at least at idle speed.
I would check the fuel trims when driving at 2000 rpm, 3000 rpm and 4000 rpm.
If the LTFT on both banks is a lot lower there, I suspect an air leak somewhere.
Otherwise it's a defective MAF.

 

Thank you, I will check LTFT at these rpm.
The Ford dealer checked the MAF and live data shows a rapid MAF response to throttle opening. I also believe the problem is likely to be caused by an air leak or maybe a faulty component?
Spraying gas under the manifold, just below the IACV still seems to cause rpm to rise. Very difficult to see much under there as it is full of "stuff" but there do not appear to be any rubber hoses there. I wonder if there could be a dodgy gasket perhaps between throttle body and manifold. If it ever stops raining I will try and build up the enthusiasm to disconnect and check the joints. It is very strange that the error is ALWAYS initiated at idle speed only but, as mpg at constant high speed is not good, I think the problem is apparent at high speed but does not trigger the error light!
Thank you again for your response. I will keep you updated, if I do not slash my wrists first!!
John

 

Thank you for your response.
The ignition timing is controlled by the powertrain control module (PCM) and cannot be adjusted therefore any errors there shold only be within the PCM or relevant sensors.

The camshaft timing is by chain, therefore with no belt, belt displacement is not possible.

I think air is getting in where it shouldn't or the PCM has developed a fault.

I am determined not to let it get the better of me, unlike the Ford main dealer!!!

Thank you again for you input.

John

 

Did you ever get to the bottom of your fault? I have similar!

 

Hello OKSid,
Yes I solved the problem by buying a new Mondeo diesel.
But seriously I sold my V6 to my son and he solved the problem. The error message indicates that the fuel is running very rich due to too much air entering the inlet. My son removed the flexible pipes connected to the inlet manifold and found a 3 inch axial split on the underside of the breather pipe from the back bank of cylinders to the manifold. I had checked this pipe, from above without removing it, and could see no problem! He replaced the rubber tube and problem was gone, fuel consumption back to normal, no error messages.
This was 2 1/2 years ago and still going well.
Hope that this helps,
Regards,
John

 

Considering this post ended such a long time ago I didn't expect a response
Very helpful, thank you for the reply John

 

One small correction, the error message indicates the engine is running too lean (not enough fuel).
That is also consistent with the air leak your son found. The MAF didn't register all the air going to the engine.

 

You are correct Oldford, the MAF registered the correct air volume as the additional air, from the split, was downsteam of the MAF. Thanks for the correction.