Focus Misfire P0301 Is A Throttle Body Problem - Know Ford Issue?

[andybaz]

Hi all, focus 2.0 16v 2004 dohc zetec.

RAC been out - told its a coil pack - mate changed his pack - still missing - called me round to read - P0301 misfire NO 1 cylinder, so armed with tools - removed plugs ready to change- carried out compression check - NO COMPRESSION NO 1 cyl. - so i told him head may have to come off for inspection.

Know, he has had some one else he knows look at it, an has been told i set my diag machine up wrong - it should have read p2135 : throttle body error etc and this is why there is NO COMPRESSION on no 1 cylinder, seemingly FORD know this as a common issue, charge £££££££'s to remove head when infact they simply remove/replace ? the throttle body ? if so, there's a lot of profit mark up in there ? and done in 1/10 of the time ?

This model is cable throttle an not FLY BY WIRE, the throttle body is a plastic item screwed to a plastic 4 branch inlet manifold feeding all 4 bores at the same time, so surely there would be compression problems on ALL 4 cylinders ?, may be there are some ford models where this issue is correct: the throttle body problem is possibly hidden under the code p0301, never come across it and find hard to believe.

So what do you all think, been in spanner trade since 1988, does a throttle body cause compression probs, whe i see it for my own eye's i will believe :P

[digidash]

your code is right....cyl 1 miss and confirmed with a compression tester. on this car i'm afraid likely burnt valves (head off) however when rocker cover off have someone turn crankshaft pully by hand (normal direction of rotation) to see if a no 1 valves stuck slightly open or a broken valve spring. (unlikely but worth checking when you start the head job incase.

for someone to say throttle body would give no compression?????? do they work in a fish shop coz they dont understand engines. regards steve

[andybaz]

Well, i can appreaite the guy thinking hard about what i told him 'head investigation &b poss removal', then spoke with a fitter friend and he poped round and said i didnt set my solus pro up right, it should have read p2135,so after talking on phone i gladly jumped at chance to go round and reread the car P0301, read the car as EOBD and then as manufacturer spec, even drew simple diagrams for the owner. Being in the trade since 1988 to date was a little baffled, always willing to learn something NEW :D , spoke to a colleague, in the trade for last 50years and we both came to same conclusion = back to shcool with our crayons :D .

I spose if i had a bore scope i may be able to see something, someone did tell me to use a comp gauge with an adapter to get a true compression value, at time of test i improvised, gauge held squarely over plug hole 1 an cranked NO COMP, then over 2,3,&4 an i get comp, obvioulsy i cant go by value as im not screwed into plug hole, then rechecked cyl 1 - tried for about 2 mins to get comp, spose i should look at my snapy dealer and see if he does FORD adapters for the future.

Cheers for your views and all those who have read, cheers andy

[digidash]

search eBay for compression tester. about a tenner delivered for a cheap one but i would advise one with a solid extension bar. i charge to do a compression test so if you give £20 for one it will earn its money back in no time. you will find yourself using it as routine before too long. also eg; very slight misfire a proper comp test will show if a cylinder slightly lower than the other 3. much quicker than checking all sensors and wiring trying to find a fault thats actually mechanical, regards steve

[andybaz]

Cheers for your view steve, i understand what you are saying, just need to find an adpapter as the ford focus plug thread starts a little way down the hole meaning most gauge equipment wont reach the 1st thread even :( , i know you can get some with a rubber coned seat to fit over the plug hole, but yes definately looking into upgradin my compression gauge equipment, even the kit a work with 5 adapters dont fit the ford system :( .