Hope some one can help my mate bought a focus 1.8 (petrol) off eBay with a known misfire it's a straight car taxed and mot,ed prob is we know it's miss firing on cylinder number 4 .it appears to have new coil pack leads and plugs but we have tried another coil pack lead and plug and swopped the injector from one cylinder to the problem one miss fire still there.

Thinking now it could be a sticky valve have not done a compression test yet .or that possibly the belt has been changed and is slightly out. Going to check that and compression check on Saturday if they both check out fine looking towards a sticky valve .has anyone had experience of cleaning them with valve cleaner and which one would you recommend .

Have looked at it possibly being a dodgy ecu but that's a last resort eml is not on at all although scanner says it's on p0304 code anyone come across similar issue could lend some advice would be appreciated.

The best cure is to use forte engine flush then refill with good oil its either the valve or the wiring to the ecu which was an issue as well also the wiring to the ecu a collapsed hose behind the throttle body under acceleration a sticky pcv valve at the front of the engine failing all that the ecu needs repaired

Pcv youll see with a hose going into the manifold thats the pcv pull it out clean it try again check the plug gaps also tgen follow that pcv hose to rear of throttle body get someone to rev the car look for it collapsing

To clarify the choices are

Faulty plug or wire

Faulty 02 sensor

Faulty cat

Poor compression

Fault in the ecu

Thanks for reply Arthur had a look at the pipe that appears to be new and does not collapse will have a look at the valve as well on Saturday you say the wiring to the ecu would this be down to corrosion from water ingress or do they tend to work loose .

Would of thought it would throw up a code if it was O2 sensor .will try and get a can of forte should all good motor factors sell it.

The wiring can get brittle and also corrode mainly the wires to the coil pack they tend to be tightly curved where it plugs in usually its the plug gaps or the coil or the wiring to the coil sometimes the 02 sensor wont throw up a code as its still in certain perameters the cat would be noticeable it would have no power and stink the final one is the ecu which has to be sent away and tested that alone is about £100 this is where its good to have it hooked up and read the live data

Sometimes taking it in can be the cheaper option missfires on the 1.8 are a nightmare to find bern there done that got the t shirt i spent a fortune replacimg bits and bobs in the end ide have been cheaper having it looked at

Forte should be easy to get ford use it on services and a few others as well

Lully enough Arthur I,ve got some bits an bobs off two old engines that came with my sons car like coil packs both ford origins as I,ve heard after market ones can cause a misfire had a good look at the wiring at the coil and appears intact .i would of thought you would get a random miss fire on different cylinders and not just on one if it was the likes of a 02 sensor .asked the previous owner about cambelt and says it was changed before they got the car and not since they have had it which seems to discount my theory that it might be slightly out .so I think I will look at giving the likes of the PVC a clean and give it the forte treatment it's worth the time and effort as the car is in nice condition inside and out .

perseverance is all i can say aftermarket leads and coil packs are rubbish and never work for long

Had a bit of a play with it yesterday and my might said it drove a lot better albeit still missing followed him out of work this afternoon and told him to give it some down the dual carriageway which he did and was doing about 80 ( sorry Stoney my clocks must be out lol) so I'm leaning towards it being a sticky valve and possible needs a good blast to clear it .so will do a forte engine flush on Saturday and clean out the relevant bits and bobs pcv ect and let you know how it goes.

hopefully it does the job you never know some fuel injector cleaner might help also again forte ide use

Arthur I have it on good authority wynns and forte are one and the same wynns took over forte about 3 years ago and both products are made in the same factory in Belgium so chances are like a well know oil giant that sells diesel and petrol oils under different guises are in fact the same product .

nice to know never used wynns before

forte advanced formula gas treatment I would recommend. Or forte specialist injector cleaner, got mine off Amazon pretty cheap plus eBay is good aswell.

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