Focus 1.8 Zetec revving/idling problem
in [Car Maintenance]
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From: Gareth Magennis on 24 Sep 2009 17:48 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. Cheers, Gareth.
From: Dave Baker on 24 Sep 2009 18:15 "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
From: Gareth Magennis on 24 Sep 2009 19:00 "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. Cheers, Gareth.
From: Tim.. on 25 Sep 2009 04:14 "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.
From: Gareth Magennis on 24 Sep 2009 15:57
"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. I shall have to Google on what the PCV valve does now, had no idea about that til now! Thanks, Gareth. |