Focus 1.8 Zetec intermittent problem
 

When travelling at a constant speed between 50 - 75mph with very slight throttle, I get a rather intermittent hesitation and the engine feels as though it's going to stop.

As soon as I apply a load by increasing throttle it clears, however the throttle response feels very fluffy, then when you give it some it pulls reaaly well as you would expect.

It's not long been serviced, so I'm considering may be in-correct plugs. It's done 75k and runs as sweet as a nut usually, but over the last few weeks the hesitation seems to come and go.

I'm getting between 35 & 37mpg at the moment, travelling 110 miles per day, all motorway mileage, so it's seem to be running well....


Any ideas guy's

Might get a better response on www.ffoc.co.uk, but it sounds like it could be either plugs, leads or the coil pack, I've got the same problem on mine at the moment, but it's at Power Engineering to have the turbo looked at so they're looking at that while it's there aswell :)

Might be worth a quick check on the wiring loom connection near to the lambda sensor .... this was a weak spot on the older mondeos as the connector would get moisture in, corrode the connector pins and it would f**k up the mixture, causing MOT failure on emissions.

On my old 1.8 (a mark 1 from 1995) it was tucked behind the front bumper skirt, easy to get at if you had ramps. All you need to do is unplug and re-plug it a few times to wipe the connectors clean.

If that don't work then check the air filter housing is sealing properly around the lip of the filter, and the jubilee clips on the inlet hoses. If no joy then try plugs or plug leads ....

Thank you both for your valued information, very helpful.

My concerns are many:

1. Plugs or leads
2. Coil pack
3. Exhaust sensor
4. Knackered cat or blocked system/backbox
5. blocked injectors
6. blocked/restricted fuel filter
7. bad fuel, maybe contaminated with moisture
7. Industion leak somwhere
8. soiled throttle body

the list is endless, though it's only just been serviced & the fault seemed to occur only a few hundred miles after that, which possible leads to incorrect plug type.

When Iput myoot down it pulls like a train, no messing & as mentioned above the fuel consumption is very good, certainly returning regular figures of an average of 36mpg....

It's very similar to turbo lag between gears.... now there's a thought

Strange one

If it's an air leak of any sort you would almost certainly feel it as you pull away from a standing start.

Earlier Focus had ECU cut out problems! You say engine wants to stop, is it as if engine dies like runs out of fuel or is it more a misfire issue. Does it feel like redline cut out?

It's a very slight misfire, and happens quite often. nothing as severe as a redline cut out.

When pulling away and changing through the gears there is a definate hesitance in progression, though when booting it it pulls fine.

This is pointing to a small intake leak somwhere I'm almost sure.....

Well if it ran fine prior to service and now its going tits up. Its more than likely ignition fault. Have you visually checked all HT leads and checked spark plugs for type and gap. Thats what I would do first, maybe HT lead is not seated correctly.

I'll have a look see :-)

Do you know I have all the tools & a fancy Snap-On tool collection from my days working in the performance game, and I now a days I can't be arsed to mess.

Me thinks, that If I ask enough questions it will solve itself, sadly not.

Cheers for your comments guy's

Update

Now that the air temp has dropped the Focus drives superb, not a hint of hesitation.

I've started to use Tesco super-unleaded '99Ron' the engine seems to respond much better, it may be more expensive but I gain the difference in cost by maintaining 36.5 mpg on nearly every tank full, which is just one mpg lower than warmer months 'all motorway mileage i might add'

Good motors

Would hazard a blind guess at a oxygen sensor problem. A slow switching sensor may not always show up on the ECU fault codes, but does give intermittant hesitation that usually clears when using large throttle openings. However this usually gives intermittant idling problems in the latter stages of failure (first stanges being hesitation and power dropping on and off ), so if this starts happening, then this would be a likely fault. Obtaining live ECU data on a test drive would easily pinpoint that (which is nice if you have the tools ;) ).

Also I would suggest a simple test while your under the bonnet, with the engine running, put some weight on and lean on the inlet manifold, if you hear any change in revs you have a gasket/cracked inlet manifold (plastic).

Coil pack....change leads at the same time,but seen many coil packs go down causing intermittant missfires on the Focus...

HTH

If it has always happened, get ford to check yours hasnt got the wrong inlet manifold on, some where fitted with the one from a mondeo at the factory and this caused some of the to hesitate, it was a recall and should be fixed for free.

If it has just started to happen, my first place to look would be to replace the throttle position sensor, this went on mine and first indication of this is when on slight throttle, it feels like its stalling but the ECU kicks in keeps it going most of the time.

if not the above check the little S bend pipe at the rear of the engine, cant exactly remember where it attached to but i think one end attaches to the inlet manifold, its only about 6 inches long, about 3/4 inch diameter, this sometimes splits on one of the bends, but this would also show up as fluctuating revs at idle.

Mark

I thought the manifold issue only affected the 2.0ls?

I had a 2.0 and had mine changed. It was not for hesitation, but cos it made a funny sound (IIRC a bit of a high pitched sucking)

not sure to be honest but the dealer checked mine wasnt effected when i had the probs and mine was a 1.8 so i can only assume it affected these too.

Mark

Solution to the intermittent problem found....

Replaced throttle position sensor, now much better. how it's affected by air temp, I haven't a clue!!