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muditmalhotra

Car Jerks(Jumps/misfire) After Service.

15 posts in this topic

Hi All



I am new to this forum and not sure how to present my problem. but i will give it a try -



I have a 2004 ford mondeo petrol 1.8 - 66k miles on the clock. It was
all good before I got my car serviced. Infact it was ok for few days
after the service hence I am not 100% sure the servicing made any
difference.



When I accelerate my car will give me small jerks(jumps / misfires). As
soon as I increase the rev the problem starts and this happens a lot
when I am in low gears splly 2nd and 3rd.



I got my car serviced 2 weeks ago and spark plugs were changed and HT Leads were NOT changed.



I am not sure what is happening now, is it due to Ht leads ? or is one
of the new spark plug isnt good or was there any fault in servicing.

I went back to mechanic and he said he can try changing ht leads and coil but he didnt sound too convincing.



Dont know what to do.



Any help will be appreciated.

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If the spark plugs were changed id say its definately either your HT leads or a coil pack required, id say its more than likely going to be the coil pack

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Also make sure it was genuine Ford spark plugs that were fitted as non gen

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Thanks for ur reply mate !

It wasnt genuine spark plug will ask company name tomorrow and let u know

Also, if ht lead or coil is to be blamed, why were these working fine before the service ?

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make sure the HT leads are on properly.

had a similar problem on out old focus, i hadnt put one lead on properly and it was misfiring.

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Non genuine spark plugs could be whats causing the problem thats what that last post was meant to say there. You tend to find they aren't correctlt spaced and dont spark properly

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If it is the ht leads or coil pack id imagine its a coincidence that they've gone wrong just a few days after the service

muditmalhotra likes this

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Just a quick search on imternet - bosh plugs are available online whereas cant find any genuine ford plugs.

Are bosh as good ?

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Bosch plugs are fine

not unusual for leads or coil to fail when plugs get changed, its something i have come across many times on the Ford.

have also come across another common problem that gives the same symptom, check the wiring and the plug that connects to the coil pack...have often found corrosion and/or damaged wires close to the connector

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As modern cars can go 50k miles without the need to change the plugs, when they are changed you often find that the leads don't like being pulled about. They become brittle after a few years and break up when they are yanked off the plugs.

I have also had a number of cases where new plugs have failed but normally if they have been gapped correctly they either work or they don't.

Coil pack could also be playing up, but I would change the leads first as they may be 9 years old and need replacing anyway.

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it was the coil pack, got it changed ¬ £90.00

sounds costly....

I asked my mechanic about what make are the new spark plugs and coil pack - to which he said its DELPHY !

are delphy any good ? he said they are ford recommended.

but for now my car run as smooth as it was.

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Delphi are a quality make so shouldnt cause any problem

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I would look also towards the basics... has the fuel filter and air filter been fitted correctly and the right direction. Symptoms you are describing can also be attributed to these!

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Taken from my thread on this:



<<<<<<<<<<<<<<<<<<<<<<< UPDATE >>>>>>>>>>>>>>>>>>>>>>>>>

<<<<<<<<<<<<<<<<<<<<<<< UPDATE >>>>>>>>>>>>>>>>>>>>>>>>>

<<<<<<<<<<<<<<<<<<<<<<< UPDATE >>>>>>>>>>>>>>>>>>>>>>>>>


I purchased a cheap throttle position sensor from ebay for £15 (genuine part normally costs £70), fitted it and didn't solve the problem, so moving on.


After some research this is what I have found with regards to the stuttering/fuel starvation/misfiring :::


ecutesting.com :::

This common fault of misfire on two cylinders or complete non start is often caused by the ignition coil pack shorting out on the vehicle - it is very important that the ignition coil pack is replaced at the same time as refitting your ECU after it has been repaired - or your faulty coil pack may damage the repaired ECU. - http://www.ecutestin...u_misfire_.html


EXCELLENT thread from RAC.co.uk on this topic :::

Lots of detail into this very common Focus MK1 98-04 fault here:



How I think the problem occurred :::

I believe that when the speed sensor started malfunctioning I continued to drive the car, which may have caused the faulty speed sensor to damage the Ignition Coil Pack which then damaged the ECU.


How I'm going to tackle it now :::

Take out the ECU, read it's part number and send the ECU off for repair/replacement by ecutesting.com for (hopefully) £150.

Purchase new ignition coil pack for £25.


Will let you know how it goes :)

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