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Mondeo - Intermittent Bucking Problem When Accelerating


Sauniere
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Hi, I have a Ford Mondeo 2.5 Turbo Ghia (2007) 4 door saloon. Recently I've noticed that after the car has been running for about 15 minutes, if i put my foot down there is a momentary loss of power, the car bucks and I have to ease off on the accelerator for it to run ok again. This also occurs from a standstill, at traffic lights for instance, I depress the accelrator and the car jerks and bucks, i have to ease off and creep forward to get the car moving but it's not every time although it will do it at some point on every journey over 15 minutes.

I've taken the car to an indie garage and they've witnessed the fault but the scanner doesn't give a fault code. They've said that they'll have to have it back to give it a general check over of wires and hoses etc to find the fault. The mechanic said he felt it was electrical. He said it's almost like someone is flipping a switch to turn the engine off for a split second and back on again repeatedly.

I've done a bit of research and have seen things like fuel injectors, fuel filters, egr valve etc but none of the symptoms of those things quite match what my car is doing. i.e there's no balck smoke, no horrific noise when idling etc. The car runs smoothly at lower speeds although there is a slight bumpy/lumpy feeling as I'm driving at say 70mph+ not that i do that of course!! :whistling:

I've noticed that this problem is worse when the weather is damp although there have been relatively few dry periods over the last few months so i can't say for sure that its a contributing factor.

I've arranged to take the car back to the garage in the next few days and I'd love to be able to give them some idea where to start as i have a feeling the trial and error approach is going to be expensive

Any help would be much appreciated!!

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i would think the obvious one to eliminate first is the possibility of contaminated fuel or a dirty fuel filter. once that is done then consider checking the egr.

what sort of mileage has the car done, and when did the filters last get changed?

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The car has done approx 50,000 miles. It's just had a major service (in Feb) but not sure if fuel filter was done, i'll check docs tonight when i get home. If it wasn't done at this service then it hasn't been done during the 4 years i've had it.

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i would think the obvious one to eliminate first is the possibility of contaminated fuel or a dirty fuel filter. once that is done then consider checking the egr.

what sort of mileage has the car done, and when did the filters last get changed?

I was thinking along those lines too (airlock in the fuel line). If the fuel filter has been changed (badly) then this is extremely likely.

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actually saying that,my old man put petrol in his diesel,and his van ran exactly the same as you're describing.long shot tho i know. ford scan would probably show it up on their IDS

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Weird update on this, on the day i picked the car up from the garage the fault appeared when accelerating from about 30mph which it hadn't done before. The next day i didn't have the fault at all, thursday morning it didn't happen. Took the car into the garage and left them with it. They couldn't get it to manifest the fault. Since then it hasn't done it once!!

I'm wondering if the fault was electrical and them plugging the scanner in has blipped something and cleared the error? Either that or total coincidence.

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if it re-occurs then get some forte diesel treatment, this might help clean injectors and allow for smoother acceleration.

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if it re-occurs then get some forte diesel treatment, this might help clean injectors and allow for smoother acceleration.

Its a (mk4) petrol turbo, i think its the Volvo 5 cylinder one (225Hp, same as the ST focus), must be one of the 1st ones

So its probably not a good idea to put diesel treatment in it ............but then again, people have been putting (petrol) 2-stroke oil in their diesel engines?

Mabee safer with petrol injector cleaner :lol:

  • Haha 1
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Its a (mk4) petrol turbo, i think its the Volvo 5 cylinder one (225Hp, same as the ST focus), must be one of the 1st ones

Spot on!

I think i might get fuel filter changed anyway to be on safe side

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  • 2 months later...

Update to this problem.

The dealer didn't want to know. So, after a lot of going back and forth to my local indie garage i was no further forward and the prolbem was getting worse. I took the car out for a long drive to see what would happen. The engine light came on!! (never thought i'd be happy to see one of those)

Back to the garage, code has shown it's the Fuel Rail Pressure Sensor that's faulty. Car booked in today to get it changed.

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  • 1 year later...
  • 4 years later...
On 6/4/2013 at 10:06 AM, Sauniere said:

Update to this problem.

The dealer didn't want to know. So, after a lot of going back and forth to my local indie garage i was no further forward and the prolbem was getting worse. I took the car out for a long drive to see what would happen. The engine light came on!! (never thought i'd be happy to see one of those)

Back to the garage, code has shown it's the Fuel Rail Pressure Sensor that's faulty. Car booked in today to get it changed.

i know its been a long time .But did the sensor sort out the problem 

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On 1/14/2020 at 11:12 AM, 5 pot said:

i know its been a long time .But did the sensor sort out the problem 

Unfortunately, @Sauniere last logged into the site 12/02/2018 so I doubt you're going to get a response.

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