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Mike, Ford Technician
Category: Ford
Satisfied Customers: 39198
Experience:  Tech Expert
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I have a 2001 Ford Focus 1.6 Zetec with around 100,000 miles

Customer Question

I have a 2001 Ford Focus 1.6 Zetec with around 100,000 miles on the clock.
It has been regualry serviced and recently had a cambelt change.
In about October last year it developed a fault where when crusing at around 65 - 70 mph the car will hicup and loose power for a split second. Seems like it is misfiring. It seems to do it randomly but only when sitting at a steady speed, never when accelerating.
It also appears to do it only when it is above about 10 degrees ambient air temperature. When it was really cold over the winter it didnt do it at all. Typically now though it will do it every couple of minutes while driving on the motorway.
I have changed fuel filter, plugs, leads, and coil pack but this has made no difference.
Submitted: 4 years ago.
Category: Ford
Expert:  Mike replied 4 years ago.

Hello and Welcome to justanswer..

My name is XXXXX XXXXX Im happy to help you with this -

Can I just ask - have you got any / get any fault lights come on at all when this happens - or when driving?

Too - have you had any plug in tests done at all - standing and in driving?

Plus - the plugs and leads you fitted - are you sure they are the correct type / Ford issue etc?


Also- when was the last oil change done - mileage / time wise.. ?

Rgds - MIKE...............................

Customer: replied 4 years ago.



No fault lights have come on.

I guess when you say plug in tests you mean connected to a computer. If so, no, I have not done this. I want to avoid the cost.

As far as I am aware they are the correct plugs and leads. Got them from Euro Car Parts.

The car last had an oil change about 12 months ago which was at about 90,000 miles.

Expert:  Mike replied 4 years ago.
Hello again Oliver -

Thank you for your reply and info.

Yes I was referring to the plug in diagnostic tests - but as you have no fault lights coming on, at this stage , that would most likely not reveal anything.

I asked about the oil change issue because on these engines, they have very small ( in comparison to some ) valves and hydraulic valve lifters in the engine head. Its critical for god / correct performance that these are kept clean - they gum up and stick. If they stick badly, they cause a misfire - bad running etc. If they just start to do it, then they can cause exactly as you this espeically to as you have done all the obvious, is a consideration here - especially too as its 12 months / 10k miles since it was done.

So what I suggest is to have an engine flush done with a good make / treatment. ( a product called Forte engine flush is the best for these valve issues - you cant buy it in the shops, its a trade only product - which is used for just these sorts of issues - but if you do a search on google etc - you will find you can buy it. )... so , to use that - and then renew the engine oil and filter- ensuring you use at least a 5/30 engine oil - no thicker.

The oil is due anyway so its two birds with one stone there -but doing it that way should free up any sticking valve lifter issues to cure that issue you have...

That is the best / cheapest way forward on this one - but I will also mention to save you time etc - in case that doesn't cure it - then I suspect you have a slight injector sticking issue. That certainly wouldn't be unusual at that mileage - the pintles on the injectors are very fine and over time do stick at certain rev ranges - Its not bad at the moment - ie, its not misfiring badly etc - so again- same company do an additive that you can simply put in the tank and drive -and it cleans the pintles as you drive. That product is called Forte Injector cleaner or injection system cleaner... ( just be sure to get the Petrol one - not the diesel )

Given your symptoms I dont think you have anything serious going on and indeed those are the common issues with these as above and so the best way forward for you now to cure that for you...

IF you were to still have trouble after that , then it would be time to have fuel pressure tests done and Live Data tests etc -- but you dont want to be spending on that before doing the above.... But espeically in the case of the fuel injector cleaner - give it 2-300 mile or so to work its magic ! Forte products are not the cheapest - but they are the best in my opinion. Just one other "tip" - when doing the engine flush - use as per instructions on the bottle - but use it for at least 20 mins.

Let me know if you need anything more on this at all -

>> >> Meantime -- Please click on the OK rating to Excellent ratings service for me now, Thank you for that... and you can get back to me anytime if you need / wish..

Best Rgds, MIKE.

Please note, you are rating the content of my "answer" - my help to you - not the "system" which can experience delays etc which are not under my personal control -or delays caused by "time -off" which we all have on occasion - Thank you.

Customer: replied 4 years ago.

Thanks I will try that. Do you know why the fault would only happen in warmer weather? I would have thought if it was valves or injectors it would happen regardless of outside air temperature. Below about 10 degrees C the fault doesn't seem to happen.

Expert:  Mike replied 4 years ago.
Hello again Oliver -

Thank you for your reply.

I did note that yes - and meant to mention, that its all most likely linked in because of the heat of the engine oil - therefore the consistency etc affecting the valve lifters -as above.

Sorry Oliver - I did mean to note that for you - but that is what I suspect there...along with the other symptoms tied in.

Kind Rgds, MIKE..

-- Please click on the OK - Excellent service ratings for me now at this point as that is how Im credited for helping you - Thank You in advance for that. You are Welcome back anytime -

Best Rgds, MIKE.

Customer: replied 4 years ago.

Thanks, XXXXX XXXXX won't get a chance to do it until next weekend but I will let you know how I get on.

Expert:  Mike replied 4 years ago.
Hello again Oliver -

Thats fine -

You can get back to me anytime if you wish / need. Per the way the justanswer site works, I do just need you to click on the OK -Excellent ratings service for me now - Thank you for that.

Nb - you can get back to me anytime - clicking the OK ratings does not close you out -

Best Rgds, MIKE.
Customer: replied 4 years ago.



Sorry for the delayed response I have not had computer access for a couple of days.

I won't know how to rate your answer until I have done what you suggested.

I have bought the oil, oil filter, and engine flush and am borrowing a pair of ramps off a friend tomorrow. Weather permitting I will get the job completed tomorrow evening.





Expert:  Mike replied 4 years ago.
Hello again Oliver -

Thank you for your reply.

I understand what you are saying -and thats fine.

Please bear in mind what I have told you is in line with the symptoms you have described to me - and the answer / suggestions I have given you are in good faith again, based on what you have outlined.

Too as mentioned , clicking on the OK ratings does not close you out at all.

Im always happy to help you further if needed - Let me know how you get on.

Best Rgds, MIKE.
Customer: replied 4 years ago.



I carried out the engine flush and have finished one tank with injector cleaner but this has made no difference. Any other suggestions?

I read somewhere it could be a small split in a vacuum line and when the ambient air temp is warmer the split opens up and when it its colder it is closed. Does this make any sense? Or do you have any other suggestions?

Something else which I have noticed but may be unrelated, when I am slowing down and put it in neutral just before I stop the revs will go up to about 2000 rpm and then when I get to a complete stop they drop down to normal idle speed. If I am stopped on a hill and then start rolling forward the revs will go up again until I come to a complete stop again.