Hi,

I had a lot of problems with my ford focus 2002. Front discs and brake pads replaced, caliper lower bolt stripped, head lights wiring burnt and connectors needing replacement.

Now all done but i now have an errror code p0340 cylinder 4 misfire.

I have a new mass air flow on order as i believe the old one is faulty as test confirms. Is the P0340 code a result of the mass air flow fault.

She runs but very badly. She starts first turn of key but idle is very rough no power heavy fuel consumption.

Any ideas as i am worried this could be a bigger problem than the mass air flow sensor.

P0340 indicates a camshaft position sensor ' A ' malfunction, and / or a camshaft position circuit malfunction

www.obd-codes.com

Been browsing web for answer come up with this as a possible

Lean Misfire
The lean misfire is another common reason for an engine "miss"—this is due to an imbalanced air/fuel ratio (too much air/too little fuel). Since an engine needs a richer (more fuel) mixture for a smooth idle, this problem may be more noticeable when the vehicle is idling. The lean misfire may decrease or disappear as the engine speed increases because the efficiency of the volumetric flow into the combustion chambers increases dramatically. This is one reason why a vehicle gets better mileage on the freeway than in the city. An EGR valve that is stuck open, a leaking Intake Manifold Gasket, a defective Mass Air Flow Sensor, a weak or failing fuel pump, or a plugged fuel filter are some of the many causes for a lean misfire.

Pay very close attention to the Long Term Fuel Trim values because they indicate how much the Powertrain Computer is compensating for an imbalanced air/fuel ratio. If the Long Term Fuel Trim is over 10 percent on one bank of cylinders and not the other, there might be a vacuum leak or defective/cracked intake manifold on that specific bank. It is important to determine what is causing this amount of compensation. Check the Fuel Trim "numbers" over the full range of operating conditions. A healthy engine should have Long Term Fuel Trim numbers around 1 to 3 percent, either positive or negative.

P0340 indicates a camshaft position sensor ' A ' malfunction, and / or a camshaft position circuit malfunction

I think he has posted the wrong dtc, think it should be p0304, thats thats cyl 4 missfire, took me a while to figure out what he was talking about

So now it could be spark plug, ht lead, coil pack , something along those lines to start with.

Ah . . . . I did wonder why the O.P.'s post after mine mentioned misfire . . . that explains it then :)

Yes i did post the wrong number. Sorry for confusion.

So after a lot of problems and the engine management light now flashing im giving up and took her into a garage for repair. And to be truthful this problem i have no idea on what it is.

Ive neglected to service her regularly so its my fault and as i need her on top form for the 19th for my drive back to the UK from Norway id rather have the experts do it and have her running right.

So thanks for all the help. :)

Picked up car tonight and after a new Coil and HT Leads she is back to her normal self. All changes to engine have certainly improved the performance. Looking for the the German Motor ways where i can really open her up and see if shes back to her old self. Pretty sure she is but it'll be fun.

Sorted :)

Hi,

Cars giving me more problems ive now got a error code of P0171 as i understand lean on bank one.

Is it a air leak or something more sinister?

A Ford P0171 is a LEAN code for cylinder bank 1

Oops, just spotted you've actually figured that out, according to one page it states ... A lean fuel condition may exist if the engine is sucking in too much air and/or the fuel system is not delivering enough fuel. If bad enough, a lean fuel condition may cause lean misfire, a rough idle, hesitation or stumble when accelerating, and/or poor engine performance.

Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow).

If the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors.

Hi, The problem for the lean code bank 1 is the lambda sensor in the exhaust. Bank 2 is under the car. i got this confirmed by a local garage to my mate in the UK who i am visiting over the Christmas break.

As Roy carter said the car wont let me down on my journey home to Norway in new year and the running will not effected apart from maybe stalling now and again if on idle. Said that ive made sure i have extended my break down coverage to cover Europe just in case.

Cost £77.17p from a Sam centre. As its a difficult job to remove through being metal in metal which will be rusted ceased in there over 13 years im leaving it till i get home and let my local garage in Norway do it. I only brought the part here as it saves me a fortune.