Own a Renault Clio and my car is really revving fast in it's stationary position. It's happened twice now in the past couple of days. First time it happened, we just took it to a local garage on the off chance to get it repaired and all the mechanic did was to really slam his foot on the accelerator for a while and the problem went away.
It's happened again and this time we did what the mechanic did with slamming the accelerator on as far it will go, only this time the problem is not corrected - it's still revving like merry hell. As it's Christmas, with no garages open, I am seeking some advive as to what it might be and whether it's safe to drive around in. It's only happened since we've had a cold snap here in the UK. Oh and btw, the car is just an incy wincy little more sluggish to start up in this cold weather.
If you need any more info, just ask and I'll try to fill the gaps in. Thanks in advance.
If it had been a car with a carburettor and an automatic choke, I'd have said that the slow-running control on the choke was out of adjustment. This happened with a 1988 VW Golf that I once owned: very embarrassing to have the engine racing away when you're stuck in a traffic on the London Orbital Carpark (I mean "M25"!) - and very difficult to edge forward at low speed, as well.
However with a modern fuel-injected car, I wonder whether could be the accelerator cable that's fraying and sticking in its sheath. If you can locate the throttle lever on the fuel injection unit (it will have the cable attached to it) you could try manually closing it to see if it's sticking open. Probably safest to do this with the engine turned off to avoid getting your hands caught up in fan-belt pulleys. Maybe also open it right up (definitely with the engine off!) to pull cable through the sheath, and see if it shows any tendency to stick instead of closing when you release it.
If it is the throttle cable, I suggest you don't drive it in case it sticks wide open while you are driving. I had a very scary experience when I was learning to drive - coincidentally also in a Renault, though this was one of those ancient Renault 6s with the gear-lever like a hockey-stick coming out of the dashboard. I was going up a steep hill so I was in low gear with the engine running fast. When I got to the top and levelled out, I thought the engine was racing a bit as I changed up, but thought I'd just muffed-up the accelerator/clutch coordination. But when I got into 4th, the car shot forward as you'd expect if you engage it with the engine running at 4000 rpm! Fortunately I realised very quickly what had happened (the accelerator pedal didn't spring back when I took my foot after it) and I switched the engine off *without turning the key so far as to lock the steering) and let the car come to rest. The worst thing I could have done would have been to press the clutch: deprived of any mechanical load the engine could have revved so fast that it suffered mechanical damage, given that it wasn't a modern car with a rev-limiter.
However I wonder if the poorer starting could be linked in any way to the problem - suggests a mixture that is too lean or too rich, assuming that the battery is OK and the engine is not so cold that it's struggling to turn over against viscous oil.
Since this over-revving has occurred I left my car overnight in the garage and in the morning just couldn't start the blighter. All the electrics had gone. Mr Car Breakdown Man came along and got it going again. Apparently the battery had lost all it's juice and was on it's way out. After he had got the car going again the car was idling at it's expected normal speed again, ie. it wasn't over-revving at all.
Mr Car Breakdown Man suggested that the problem with the over-revving could be due to the battery being on it's way out, as so much relies on the computer chips in the car to control most things, that a dud battery supplying the electricity could cause problems. He suggested to get a new battery.
This sounds reasonable to me as the car has had the occasional probs starting up in the morning and what with this over-revving and battery dying on me, well it seems to fit the picture. But, I'm no mechanic and I wondered whether the dying battery sounds a reasonable cause for the over-revving of the engine. Does anyone have any opinions as to whether the cause of the over-revving being the dud battery, as suggested by Mr Car Breakdown Man, was about right?
HHHHHHHHmmmmmmmmm........ I highly doubt the battery is a primary cause for the over-revving symptom, since it still had enough "juice" to start or at least turn the engine starter over?
If you had a true dead battery, mayhaps. That might cause memory failure in any computer controls, but they would normally re-set after power was applied and available again.
I'd still look at all the mechanical linkages and cables first. Blast everything you can see with either/and/or a spray carb cleaner or spray lube, and work the cables/linkages by hand to loosen them up. Engine off, of course.
Just to make sure, put a voltmeter to the battery. It should read at least 12 volts, optimal about 12.6 with the car off. Then start the car, and check again. Voltage should go up, as the battery is charging, NOT down. If the voltage when the car is running is equal to or lower than the normal voltage then u have a bad charging circuit. Charging voltage should be around 13.6v. If both of these check out ur electrics are fine and u should give the car fixy guy a knowlegeable talking to. All things considered, this doesnt sound like your problem. The car should stall before the computer would play up, electronics like this usually run fine on about 10 volts. Mechanical linkages sticking sounds reasonable to me.
If anybody's interested, I have an update on my car situation. We had a few other probs with the car, so we put it in the garage. It turned out to be a loose live wire connection to the battery - as simple as that and everything is running smoothly again.
However, not being a car type of guy, I still don't fully understand how a loose wire can cause over-revving of the engine. Strange things these cars!!
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