Fault with Fiesta but don't know what - help!

owsaboutthatthen

Just wondered if anyone can help? I have an R reg Fiesta 1242 cc engine (mileage only 48k). The problem I am experiencing is (and I will try to describe it as best as I can) when driving along there is like an intermittent "pull" or a "chug" like the car is struggling in the gear it is in but it is perfectly fine speed wise. It seems to pull as I'm going up and down through the gears too. It is very temperamental and doesn't do it all the time. It doesn't make it a comfortable drive and find i'm jerking forward when it happens. Had two mechanics look at the car and the first said I needed to see an auto-electrician - the second (who has auto-electrical experience) said he thought the plugs needed replacing and I needed a new exhaust (middle and back) because there were holes. So, I paid for my plugs to be replaced and then arranged for a new exhaust (only back box needed apparently from the exhaust "expert"). Drove off and found out I am still experiencing this "chugging, pulling, jerking" when driving.

Does anyone have any ideas?

Conor_3

The plug leads fail typically every 40,000 miles. Duff plugs also put additional stress on the leads as a higher current is needed for them to still create a spark. I take it it's only doing it on light throttle, i.e when you're maintaining a speed, and not on acceleration/deceleration?

Only buy the plug leads from Ford, the aftermarket ones seem to fail earlier on this and "normal" Zetec engines and the price difference isn't that much. It should be no more than £40 for a new set of leads.

student100

I had an old (P-reg) Fiesta which started doing similarly (it got progressively worse over a few weeks). Turned out to be the leads (that connect to the plugs) rather than the plugs themselves (though when they replaced the leads they did new plugs too).

Replacement leads+plugs plus labour was about £70 from a local garage. (Maybe I could have got it done for less, but IMHO that price was worth it...).

vansboy

If the 'electrical' side of things is as it should be, you'll be looking at a fuel problem, possibly.

Has it run low in the tank, prior to the fault - might have picked up some sludge/contaminent? It will need some more investigative work.

Are all the plastic pipes/ducting to the air filter in place, not worked loose?

Air filter not clogged?

Any loose wires/ cables/pipes around any of the engine, especially where you've had people looking at the plug leads?

For more detailed help http://www.honestjohn.co.uk clik The Backroom clik Technical

VB

owsaboutthatthen

Thanks for all your advice - I have arranged to take it back to the guy who told me my plugs need replacing and exhaust. He did fit genuine Ford plugs for my particular engine. But as student100 said it could well be the leads that attach the plugs (as the plugs have been replaced and it is still doing it!). I am female and no disrespect to any female money saving mechanics out there but I know zilch about the mechanics of a car, only how to drive one! Fingers crossed tomorrow, after some "investigative work" we may find out what the problem is because the car runs great apart from this nuisance problem!

owsaboutthatthen

Just an update plugs, exhaust and coil got changed but still doing the same thing - going to have the air filter/oil changed and the sensor crank (?) looked at - fingers crossed other than that i'm clueless and so are the experts!!!

knowledgeman

student100 wrote: »

I had an old (P-reg) Fiesta which started doing similarly (it got progressively worse over a few weeks). Turned out to be the leads (that connect to the plugs) rather than the plugs themselves (though when they replaced the leads they did new plugs too).

Replacement leads+plugs plus labour was about £70 from a local garage. (Maybe I could have got it done for less, but IMHO that price was worth it...).

You got burnt

I had to get that done and the plug leads were £15 plus another £10 for labour, mechanic only charged £5 labour as a simple job

owsaboutthatthen

I got charged £20 in total for plugs and labour! £10 in total for coil replacement and labour and £30 in total for exhaust to be supplied and fitted - so far £60 and the car is still doing the same thing!

thescouselander

MY girlfriend has similar problems on her Fiesta - I tracked the fault down to a faulty air flow sensor. They are the hot wire type and they tend to get dirty which affects the reading they give out causing the engine to run too lean.

One way to diagnose the air flow sensor is to unplug it when the engine is playing up, if the engine runs ok with the sensor unplugged than thats your problem. The sensor is located in the intake pipe imediately after the air filter box.

If the air flow sensor is at fault it can be cleaned by spraying it with contact cleaner (IMPORTANT - USE THE SORT THAT DOES NOT LEAVE ANY REDIDUE using anything else could contaminate the wire) Also be careful not to touch the hot wire with anything as it is very delicate and could brake.

Roosh

Once had a R reg Ford Escort. Similar thing happened with that car. I was told that once the HT leads are taken off, they always have problems once reattached. The answer was to have a new set of leads,which I bought from Ford dealers. New leads and plugs cost around £60 (can't remember exact) and I put them in myself. Rather expensive, I thought, but it did solve the problem.

owsaboutthatthen

Well took the car back to the same guy who suggested a new sensor crank (?!) is this the same thing as what you are talking about scouselander? Anyway it was very frustrating because all the way to the garage the car was running fine! Typical tho it has been like this fine one minute then playing up the next! Anyway had the work done (only charged £5 believe it or not cos he is a family friend) and it hasn't done it all day so fingers crossed!