squizxr

Hello lads, the missus has a 1.4 Focus with 147k on the clock!! Its got a few problems!! When driving, soon as you engage the clutch to change gear, the revs pick up!! Then when your stopping, car out of gear/foot on the clutch, it revs up to around 3k, then as soon as you stop in traffic the revs die down!! Even if you roll down a hill, not in gear etc, the revs still pick up until you stop!! Idle control valve??

Also, when driving on the motorway, it hesitates, almost like its goin to run out of petrol, but it never actually cuts out!!

Cheers

Camel Fiddler

First part sounds like vacuum leak. Check down back of engine where throttle body is by spraying carb cleaner on specific areas. The revs will change when you hit the spot. Can't comment on hesitation but may be linked.

northernmonkey

I'd fancy IACV to be honest

danme1987

Check that the temp gauge is working to! if its not working on the dash there is your
answer. if not point at the iacv like said

squizxr

Cheers for the replies lads!!

Temp gauage works fine, but why would the temp gauge not working make it idle at 3k??

Thing is, once its idleing properly, it wont rise unless you start moving the car!! Even if the car rolls without the throttle or clutch being applied, the revs still pick up!! Surely if it was a vacuum leak it would do it whether the car was moving or not??

hutch91

Ive had the same problem i found that if i disconect the battery for 30 mins once a week it works fine, someone told me that it resets the ecu wether thats right or not im not sure but it seems to work for me

phil_focus

the focus will hald the revs up for a smoother gear change which is not a fault but this does sound like a fault. i recon its the VSS in the gear box. they are notorious for playing up and holding the revs high when aproaching junctions and when they get really bad the speedo stops working too.

its worth getting that checked out.

Jeffers_RST

i had exactly the same problem in a 1998 fiesta 1.3 and a 2000 focus 2.0 they both revved up when the foot is on the clutch, but would hit idle as soon as you stopped. i must admit its pretty fucking annoyin, makes you look like you cant drive! i had the fiesta looked at and they said it was something called a throttle potentiometer. never heard of it. plus it was 100 quid and the motor couldnt have been worth much more! lol. aside from that, be with removing your iscv and giving it a clean.

Cheers! neil

phil_focus

throttle potentiometer = throttle possition sensor

doubt its that tbh.

Jeffers_RST

well yeah makes sense was just saying what they told me. when i thought about it, it didnt seem to add up, but i wasnt bothered anyway.

B19 JUB

check the crankcase valve pipes as they collapse and engine compensates for the problem by increasing revs.depending on engine type its either going to be a thinnish pipe at the back of the manifold that goes to under the coil pack or inbetween the inlet manifold as a y style vaccum hose

martysmartie

iTrader: (1)

What he ^^ says, it sounds like an air leak to me, check the famous T piece on the vaccum hoses which splits and thus causes an air leak, which would cause what you describe!

Yes if you coast with the car out of gear AND the clutch released the revs will raise this is perfectly normal and shows the VSS is working as this is where this is the input responsible for doing so! If you hold the clutch in and coast you will notice the revs won't rise!

ISCV is opening causing the high revving and shows it is working! If the revs are dropping to the point of stalling the ISCV will bring them up to prevent it from happening.

Martin

squizxr

Cheers for the replies lads!!

I havent driven it for over a week now, but from memory, if you hold the clutch in and coast then the revs still pick up!!

ISCV and IACV, you lot may aswell be talking Spanish Where am i gonna be able to find them to give em a quick clean??

Cheers

focii dan nick

i would say its not the iacv as this is for when the clutch is pressed or idle, to let air pass the throttle body, commonly making the car stall and not idle if this is faulty.
as you accelerate you open the butterfly valve/throtle body to let air feed the engine when idle the valve is closed so no air to make the bang.
i cant see it increasing the revs

focii dan nick

the air idle control valve is located on the side of the throttle body. it is a steel cylinder about a inch long. took me about half hour to replace but i droped the screws dope haha

martysmartie

iTrader: (1)

The ISCV can increase the revs if it is told to do so as in this case but as I said above I am with you, I doubt it's the ISCV itself!

To OP revs should not raise when coasting with clutch disengaged, I only know it when coasting with clutch released, I think it has to recieve both VSS and clutch input signals to raise idle speed.

Martin

martysmartie

iTrader: (1)

[QUOTE=squizxr;5345460]Cheers for the replies lads!!

Temp gauage works fine, but why would the temp gauge not working make it idle at 3k??

[QUOTE]

On the Focus the CHT sensor supplies the info to the ECU on engine temp, this same info is also used for the temperature gauge and for fan control. So if it was not working this would cause fuelling issues.

Martin

TBird

Hi folks

Bought a 1.4 Focus a few months ago and having similar trouble with the revs.

If I reduce speed (for example come off the motorway) the revs take forever coming down.

And if the engine is warm and I'm doing a lot of stopping and starting (traffic lights etc) it's really revvy.

If I put the clutch down the revs go right up to 3.

It roars like crazy for about ten seconds then finally settles

I took it to a mechanic and he thought it may be the Throttle Body (which was seized up), so replaced that and no difference.

Then he thought it may be a crack on the inlet manifold. It wasn't. He also tried a full oil change and squirted WD40 anywhere that might do some good.

Any suggestions (in layman's terms please, I barely know how to open the boot)

Thanks

martysmartie

iTrader: (1)

The vacuum hoses can split, thus causing an air leak!

I would check this first, they are at the front of the engine either visually inspect them or sparingly spray WD40 with the engine running, if the revs change then you have a leak.

Martin