Anyone Got Any Bright Ideas? Engine Malfunction

[juliasmith1977]

I come in desperation...

MK7 (2009) petrol fiesta titanium with just under 100,00 miles.

Total novice, not a clue about cars.

I believe this started some time back when I noticed that first thing in the morning I was having to give the accelerator a bit of welly when the car started just to get the revs up and get going. Nothing awful - nothing that unusual, but I had never had to do it before which made it noticeable.

That started about 4-6 months ago.

In the last month a proper fault has now occurred.

It started on the motorways (as all my dramas seem to) and I noticed it would occasionally glup - that how I would best describe it - perhaps misfire (although this isn't being reported in the faults). This was very intermittent and went away after a couple of days only to return a week later. It got progressively worse and eventually it pinged the 'engine malfunction service now' light on and went into limp mode. If I turned the car off and started it up again this would clear and I'd go on my merry way.

I booked it into the garage at which point it miraculously fixed itself. No fault codes were logged and I was sent on my way. A week later it started again and became pretty much undrivable. I limped / bunny hopped to the garage (at this stage the turn it off / turn it back on trick had stopped working and we were in permanent malfunction & limp mode) where a throttle sensor fault was recorded and accordingly a new throttle pedal / sensor fitted along with a new air filter and new spark plugs.

This new throttle pedal allowed the garage to clear the fault and went on my merry way with the car in perfect working order.

For one day.

The next day (when it was absolutely hammering with rain...just mentioning incase) the gulping started again and the engine malfunction pinged on. It was my Birthday and I was determined to go out so I drove it wisely or unwisely. It was gulping, pinging and limping the whole way. Then it was fine the whole way back. It then drove OK for a few days but very sluggish. Other people said it was fine but I knew it was not how it should be at all.

I called on a friend of a friend who plugged her in again and reported that the throttle sensor fault was once again logged. However it allowed him to clear it and he reset the sensor. It then drove like a dream for a week. Back to her old self, perfectly fine, except one thing - a rough idle I believe it's called. Revs up and down all over the place and occasionally stalling when I came to a stop. Usually this would be OK after 15 minutes of driving.

Then it rained. Again - may be a total co-incidence. The gulping started and within moments we were malfunctioning.

She's been plugged back in and no fault codes are showing.

Since then it has settled into some sort of consistency (rain or shine).

When you first start her up she is a nightmare. A very rough idle up and down all over the place, smells pretty petrol-ly. I can sit in it for 10 minutes totally stationary and not touch a thing and it will go up and down all over the place and eventually engine malfunction will ping. If I drive it will gulp and judder along malfunctioning all the way. Going into limp mode now causes the car to come to a total stop whereas before I could drive it in limp mode. I have turn the engine off and restart and wait for it to do it again. Stop and start and keep repeating for about 10 minutes. Then suddenly - we are off - all completely fine, rough idle is fixed, no more gulping, everything fine, she will take me wherever I want to go.

So I wondered if anyone had any ideas. I have a feeling I did not need the throttle pedal since it has done nothing to fix the fault and can see myself being trapped in an endless cycle of replacing random sensors that do not need replacing, whilst the underlying fault remains.

All bright ideas warmly received...!

Sorry for the epic tale.

[danzetecs1600]

Im certainly no expert but with my own experiences it might b the mass air flow sensor. I believe it tells the cars computer what the temperature of the air is and allows the engine to set the amount of fuel needed to be running correctly. If this sensor starts to break down the engine will start to either overfuel or underfuel because it is getting a faulse calculation of the air condition possibly resulting in rough running of the engine. You can I think check this by removing the plug from this sensor and running the engine to see if it actually improves the engine running. I am NOT a mechanic so I would still get more opinions before taking any action. Hope this is of some use to solving your problem.

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[SandyCat]

Problems like this are horrible because they could be so many things and it's a case of trial and error replacing stuff until you find the right one.

Odd thing is this sounds very similar to the problems the Mondeos had with their diesel engines and normally a good dose of injector cleaner would sort it and it normally was worse in cold weather. I am not saying this is the fault here but I am wondering if it is fuel related either pump, injectors or fuel filter. May be worth adding to the list of stuff to check.

[InKontrol]

I'd try and find someone who has a scan tool that shows you real time data, e.g. short term fuel trim, long term fuel trim, throttle position etc etc.

I'm not a fan of chucking parts at a car in the hope it'll fix it, but rather a thorough diagnosis and technical head is needed.

Check out ScannerDanner on YouTube, he's the first guy I'd take my car to if he was in the UK.

[SandyCat]

Same here but not everything has a sensor on it so won't show up via the OBD sadly.

[mick85]

Sounds like a wiring issue when u replaced the pedal was wiring tested was it ford dealership where job was done

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[JonBon]

My other half Hyundai had something that is seemingly the same as your describing, we first had the coil packs changed, diagnostics reported no faults, then a couple of days later the kangaroo hopping etc but no misfires but fair loss of compression in waves with seemingly no consistency to why or when, after a new ECU, god knows how many new sensors and people saying try this, try that, and then the labour costs I said, let's go and buy you a new car, we got rid of the old one, which only had 44k on the clock and by the time we got rid 6 garages were left scratching there head with the only thing each could come up with was basically gut the engine bay and start over. This isn't going to be what you want to hear but sometimes the worst thing is the best thing, maybe it's time to bite the bullet and cut your losses.. If we hadn't spent nearly 2k trying to fix the old one we would have had 2k more to put to the new one.. It definitely needs serious weighing up.. :(

[juliasmith1977]

Thanks all for your replies. She is back in the garage today with the strictest instruction not to spend a single penny without my say so! Some weighing up definitely required... I can sense the vicious circle approaching but you never know - prehaps for once in my life I will be pleasantly surprised...!

Thorough diagnostics and a technical head is definitely what's needed here... Just not sure where to find them!!