Ive got a 98 1.6 focus and there is a problem with the revs.

It idles fine and revs up fine but when you back off the pedal and the revs come below 2000 the engine stutters and drops down to about 300 and sometimes stalls or picks the revs back up.

It also does this while slowing down too.

Any help appreciated.

 

sounds like your speed sensor has gone faulty its located ont the gearbox, or possibly your air idle control valve on the throttle body

 

Ive cleaned out the aicv and it is running better but the problem is still there and what should i look for on the speed sensor.

 

theres nothing really to look for its just a replace jobby. this cured my 1.8 having the same problems, rough running, not idleing ect. but be carefull if you do replaceit can be a bugger if you break the pin like i did, half hour job turned into a day job lol

 

throttle position sensor

 

Are these right -

http://cgi.ebay.co.uk/NEW-FORD-MONDE...item45f839cb0d

http://cgi.ebay.co.uk/NEW-GENUINE-FO...item3caa6d1486

 

I'd replace the idle control valve first, the most easiest to do and the one most likely to be giving you the issues! Cleaning it isn't always the answer as they are so sensitive.

 

I did notice a bit of an improvement after cleaning it up ill change that first.

Thanks.

 

they look like the ones just make sure its the corrct one for ur car saves hastle later. and yea defo change AICV first the speed sensor is a nightmare

 

I personally don't think it's the VSS due to the fact you say it idles fine! From that description it sounds more like an air leak to me, have you checked the vaccum hoses as it's a very common problem with them cracking thus introducing an air leak!

Easiest way to check VSS before simply just replacing it is to coast in neutral AND release the clutch at around 10MPH the revs should rise to around 1400RPM thus showing the VSS to be working, also this would effect your speedo I would have thought.

Martin

 

I'd be thinking a vaccum leak or perished / collapsed hose. Check the PCV (positve crankshaft vent) hose under the manifold. There is one end attached to a valve that can get full of gunge. It's a cheap replacement from ford, but a bit fiddly to change. Use a long pliers to remove it.

 

Thanks for that what other hoses could I look at?

And id does seem like its sucking in too much air.

 

LOL thats exactly what I said above? "From that description it sounds like an air leak to me, have you checked the vaccum hoses as it's a very common problem with them cracking thus causing an air leak?"

As I say the vaccum ones are the usual suspects so check these first.

Martin

 

Where is the vacuum hose located?

Also how should the ht leads be set out?

They where all taken off when the coil pack was changed but I don't think they were put on properly.

 

The hoses run across the front of the engine etc, the PCV one can collapse with age but there are others.

The HT leads have to be connected in relation to firing order, I.E 1,3,4,2, if put back on wrong the car would misfire.

Martin

 

I cant find the pcv hose and how is the firing order matched up to the coil here is how mine is -

 

That's wrong, cylinder 1 is on the left, and it goes 1, 2, 3, 4. There should be a sticker on top of the coil pack saying what goes to what plug.

 

The PCV is located on the front of the enginne low down.

Martin

 

Ive been looking for the pcv but cant find it and ill look at the coil pack tommorow.

The car is going in to see whats wrong tuesday if I dont sort it by then.

Thanks everyone.

 

It's under the manifold, the 4 pipes on the engine. It's a rubber pipe with 3 outlets on it.

 

Ill give it another look tomorrow didn't really get a chance today.

 

i cured mine with swaping the pipes mate it runs from behine the inlet and runs round the engine conecting to the pcv, it has a join just under the thermostat housing iirc! mine had a split around 3inch long

 

Well the aicv is working, at least when you run live to it it clicks open and I got fed up of it so its up the garage this week now.

 

Did you ever get this sorted? My 2002 1.6 (Zetec SE) has this problem sometimes. I've tried a new idle control valve and PCV. No splits apparent in vac hoses. The Ford garage diagnostic showed no fault and after more than an hours labour cost they found no reason why it should happen.
I had the cam belts replaced not long after I bought the car and the fault has been only since then - but I cannot imagine their is a connection.
Replacing the speed sensor?