Focus 1.8 Zetec revving/idling problem
in [Car Maintenance]
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From: Duncan Wood on 25 Sep 2009 08:13 On Thu, 24 Sep 2009 20:57:21 +0100, Gareth Magennis <sound.service(a)btconnect.com> wrote: > > "Tim.." <the.farm.no(a)spam.btinternet.com> wrote in message > news:_e6dnRFuQYOw4SHXnZ2dnUVZ8sydnZ2d(a)bt.com... >> >> "Gareth Magennis" <gareth.magennis(a)virginmedia.com> wrote in message >> news:%RSum.218935$6W1.68390(a)newsfe05.ams2... >>> >>> "Dave Baker" <Null(a)null.com> wrote in message >>> news:h9gr1n$8p1$1(a)news.datemas.de... >>>> >>>> "Gareth Magennis" <gareth.magennis(a)virginmedia.com> wrote in message >>>> news:nORum.373422$RV1.181221(a)newsfe26.ams2... >>>>> Hi, >>>>> >>>>> I recently bought a 1999 Focus 1.8 Zetec. It has a problem that at >>>>> first I took to be the Idle Speed Control Valve, but now I'm not sure >>>>> at all. >>>>> >>>>> When you take your foot off the accelerator at speed, the engine >>>>> takes >>>>> a long time to lose revs, so there is no immediate engine braking, >>>>> and >>>>> also each gear change is accompanied by a highish revving engine on >>>>> depressing the clutch. Often it idles fast, before settling down to >>>>> proper idle speed. >>>>> My Astra had a dodgy ISCV and this Focus behaves almost exactly the >>>>> same as far as the fluctuations in idling speed goes, though it never >>>>> affected the engine at higher revs the way the Focus does. >>>>> >>>>> With the car at a standstill and revving, I can't recreate this slow >>>>> to >>>>> return to idle problem. (??) >>>>> >>>>> I attempted to remove and clean the ISCV today but found it >>>>> inaccessible - couldn't even see it. I also took off the air >>>>> ducting >>>>> from the throttle housing and cleaned the butterfly valve and seats >>>>> with carb cleaner, which had LOTS of black oily stuff all over it. >>>>> I'd like to go back and perhaps do a more thorough job of this. >>>>> >>>>> Basically I'm wondering what might be the cause of the engine not >>>>> returning to idle promptly under load. >>>>> >>>>> 58000 miles, full service history up to 54000 miles 3 years ago, so >>>>> only done 4k in the last 3 years. Engine otherwise seems fine. >>>>> Engine management light is not lit, and the bulb works at ignition >>>>> on. >>>> >>>> Fuel cut off fault perhaps. FI cars should cut the fuel when you lift >>>> off above certain rpm and/or road speed to save emissions and petrol. >>>> Sounds like yours is still pumping fuel in unless the car is >>>> stationary. >>>> Maybe it's the road speed sensor at fault but this is not really my >>>> area >>>> of expertise. >>>> >>>> If the intake system is really that badly clagged up then maybe it's >>>> breathing a bit heavy anyway. Do a compression test. >>>> -- >>>> Dave Baker >>>> >>> >>> >>> Thats got me thinking - also if the throttle position sensor wasn't >>> showing zero throttle at lift off, would the ECU still try to inject >>> fuel, and if so, would the engine continue to rev despite the closed >>> butterfly valve? >>> >>> Just trying to get a handle on how these systems inter-react. >>> >> >> Yes, and yes, but a stuck TPS will cause a stuck high idle on these. The >> programming is also such that immediately you lift off it fully opens >> the >> ISCV which lessens engine braking. It's an emissions thing. >> >> What rpm does it idle at stationary in neutral, clutch up, a/c off? >> Should >> drop to ~650rpm after about 1 second of holding at 900rpm. >> >> Does it warm full up hot- i.e. thermostat? If not then this will make >> the >> idle speed hang, as will a faulty PCV valve (common- under the ex >> manifold) >> >> Having said all of that, all Foci tend to display what you may initially >> find un-usual idling characteristics- it is how they are programmed. >> Idle >> flare on cold start to 2000rpm is normal too, and so is other behaviour >> the moment you hit the a/c. >> >> Tim. >> >> > > Hi Tim, > idles stationary at about 700, very smoothly. I've noticed the holding > briiefly at higher revs when coming to a stop, and also noticed revving > whilst stationary also has this "soft landing" thing going on before > idle. > I've also noticed the cold start flare to 2000, good to know these are > normal. > There is no AC on this car. Thermostat sits at about half way, 12 > O'clock. > > > Interesting you say that lifting off opens the ISCV, I thought that on > the > overrun, no fuel at all was injected, which I assumed meant no ISCV open > either. (The ISCV is an air valve isn't it?) Or are you saying this > will > only happen with a faulty TPS showing open? > > Correct me if I'm wrong, but my thinking was that if the engine is still > freely revving at road speed with the throttle shut, (and clutch > depressed) > it must be getting air as well as fuel? Meaning either dirty butterfly > valve, ISCV open (too much), or a leak? Since it doesn't do this > stationary, that seems to point to the ISCV? I suspect my logic is a bit > faulty here. > Possibly, after the engines been under load it will briefly hold the idle valve open to reduce emissions so it'll holdrevs, but it should be brief, as there isn't any load when the engines stationary it won't bother. > I shall have to Google on what the PCV valve does now, had no idea about > that til now! > > > > Thanks, > > > Gareth. > > > >
From: Gareth Magennis on 25 Sep 2009 11:06 >> >> Interesting you say that lifting off opens the ISCV, I thought that on >> the >> overrun, no fuel at all was injected, which I assumed meant no ISCV open >> either. (The ISCV is an air valve isn't it?) Or are you saying this >> will >> only happen with a faulty TPS showing open? >> >> Correct me if I'm wrong, but my thinking was that if the engine is still >> freely revving at road speed with the throttle shut, (and clutch >> depressed) >> it must be getting air as well as fuel? Meaning either dirty butterfly >> valve, ISCV open (too much), or a leak? Since it doesn't do this >> stationary, that seems to point to the ISCV? I suspect my logic is a bit >> faulty here. >> > > Possibly, after the engines been under load it will briefly hold the idle > valve open to reduce emissions so it'll holdrevs, but it should be brief, > as there isn't any load when the engines stationary it won't bother. > > > Ah, well if that is the case, and the ISCV is reluctant to always close properly or quickly enough, that would fit all the symptoms I'm having perfectly. I never imagined it would be used for anything other than idle control. Cheers, Gareth.
From: Tim.. on 25 Sep 2009 15:09 >> > > Hi Tim, > idles stationary at about 700, very smoothly. I've noticed the holding > briiefly at higher revs when coming to a stop, and also noticed revving > whilst stationary also has this "soft landing" thing going on before idle. > I've also noticed the cold start flare to 2000, good to know these are > normal. > There is no AC on this car. Thermostat sits at about half way, 12 > O'clock. > > > Interesting you say that lifting off opens the ISCV, I thought that on the > overrun, no fuel at all was injected, which I assumed meant no ISCV open > either. (The ISCV is an air valve isn't it?) Or are you saying this will > only happen with a faulty TPS showing open? > > Correct me if I'm wrong, but my thinking was that if the engine is still > freely revving at road speed with the throttle shut, (and clutch > depressed) it must be getting air as well as fuel? Meaning either dirty > butterfly valve, ISCV open (too much), or a leak? Since it doesn't do > this stationary, that seems to point to the ISCV? I suspect my logic is a > bit faulty here. The ECU fully opens the ISCV on these when you lift of - it reduces the pumping losses on overrun with the effect of less engine braking. ISCV's do start sticking after about 80k or so;- you can clean them, but due to the bloody awful access to them, its hardly worth it, just put a new one on. Hope this helps.
From: Gareth Magennis on 25 Sep 2009 15:35 "Tim.." <the.farm.no(a)spam.btinternet.com> wrote in message news:TNCdnepH55AMiCDXnZ2dnUVZ8nCdnZ2d(a)bt.com... >>> >> >> Hi Tim, >> idles stationary at about 700, very smoothly. I've noticed the holding >> briiefly at higher revs when coming to a stop, and also noticed revving >> whilst stationary also has this "soft landing" thing going on before >> idle. I've also noticed the cold start flare to 2000, good to know these >> are normal. >> There is no AC on this car. Thermostat sits at about half way, 12 >> O'clock. >> >> >> Interesting you say that lifting off opens the ISCV, I thought that on >> the overrun, no fuel at all was injected, which I assumed meant no ISCV >> open either. (The ISCV is an air valve isn't it?) Or are you saying >> this will only happen with a faulty TPS showing open? >> >> Correct me if I'm wrong, but my thinking was that if the engine is still >> freely revving at road speed with the throttle shut, (and clutch >> depressed) it must be getting air as well as fuel? Meaning either dirty >> butterfly valve, ISCV open (too much), or a leak? Since it doesn't do >> this stationary, that seems to point to the ISCV? I suspect my logic is >> a bit faulty here. > > The ECU fully opens the ISCV on these when you lift of - it reduces the > pumping losses on overrun with the effect of less engine braking. > > ISCV's do start sticking after about 80k or so;- you can clean them, but > due to the bloody awful access to them, its hardly worth it, just put a > new one on. > > Hope this helps. Yep, that helps a lot. I noticed Europarts sell them for about 45 quid, but currently out of stock. The mechanic working next door to where I work only wants 20 quid to fit one, if I source the part, which sounds like a bargain. (He does naughtily park his customers cars in our car park so I reckon this might be a bit of a friendly trade!) Thanks very much, I didn't really want to get a new ISPV fitted without being fairly sure this was the problem. Cheers, Gareth.
From: Davey on 26 Sep 2009 05:23
Gareth Magennis wrote: > Hi, > > I recently bought a 1999 Focus 1.8 Zetec. It has a problem that at > first I took to be the Idle Speed Control Valve, but now I'm not sure > at all. > When you take your foot off the accelerator at speed, the engine > takes a long time to lose revs, so there is no immediate engine > braking, and also each gear change is accompanied by a highish > revving engine on depressing the clutch. Often it idles fast, before > settling down to proper idle speed. My Astra had a dodgy ISCV and > this Focus behaves almost exactly the same as far as the fluctuations > in idling speed goes, though it never affected the engine at higher > revs the way the Focus does. On Ford Focus, this is caused by the Throttle Position Sensor being faulty. Replace it. You can clean up the ISCV, which is a good idea as a service job anyway, but you will still likely have to change the TPS to cure the fault. Once swapped out, reset your ECU by disconnecting battery or take out appropriate fuse for a few hours. |