Accelerator stuck wide open while car is going fast: what should you do?

[NY]

When it happened to me, I tried that after I'd got the car safely stopped, and it was a dismal failure. The pedal just came up, leaving the cable where it was: the way the linkage between pedal and cable was designed meant the pedal would only exert a *pull* on the cable, not a push. It relied on the spring in the linkage at the carburettor to return the cable to its normal position and push the accelerator pedal back up.

And the strands of the cable had frayed close to that carburettor linkage so that only about half of them were pulling the linkage; the other half were jamming the cable against its sheath. No amount of pulling or pushing would move the cable in the sheath: it was buggered.

My dad drove home very slowly: he jammed the throttle slightly open and then varied the speed by varying how far he pulled the choke out, using the slow-running control of carburettor choke mechanisms.

I must have had a jinx on that car because on another occasion the linkage between the lever and the gearbox broke, causing the gear lever to flop upside down as I changed from reverse to first. My dad claims I uttered the immortal words "Is is supposed to do that?" :-) There was an over-the-engine rod from the dashboard-mounted gear lever knob (this was a Renault 6 which had the same type of gear lever as a Citroen 2CV) and this engaged with a conventional-looking gear lever rod sticking out of the gearbox which was in front of the engine. A plate with a large hole was welded to the horizontal rod and this went around the vertical rod, so as you pushed and pulled the knob, or rotated it, this translated to forward-backward or side-to-side movement of the gearbox rod. The grommet between the two had come out, allowing them to become unmeshed.

(1 is horizontal rod from dashboard, 2 is vertical rod from gearbox, 3 is plate which engages between one and the other)

[NY]

Yes, keyless ignition and electric handbrake are both a bit all-or-nothing. I'd not thought about the engine stop/start button would electrically engage the steering lock. I wonder if there's any safety interlock which prevents the steering locking if the car is actually moving when it's operated, or whether it really does lock immediately. Not very sensible if you need to use it as a kill switch for the engine. Maybe the presence of the remote keyfob in the car prevents it allowing the steering to lock, and it only locks once the keyfob is out of range when you leave the car.

If it's all the same with you, I don't think I'll test this the next time I happen to drive a car with keyless ignition :-)

[NY]

The video that started all this showed the driver moving the selector lever from D to N while doing "120 mph". I wonder whether any auto transmissions allow the lever to be moved to N whe you are not stationary.

As I said initially, this was a very old car (about 1975, IIRC) with no rev-limiter or ECU. So valve-bounce and rate of fuel delivery from the carburettor may have been the only limits on the engine speed under no load.

Maybe, for all the load noise that a no load engine makes at high revs, it wouldn't seize up and maybe throw a piston out of the cylinder head or jam the transmission even with the slight clearance between clutch pads and flywheel when the clutch is down. I wasn't about to find out, and decided to stop the whole engine rather than just disconnect it from the wheels.

[Bob Eager]

I don't think it does that. I hear the lock engaging when I leave teh car, but also if I sit in it for a while with the engine off.

Yes, although there seems to be a timeout too.

[Brian Reay]

Good point.

Our Outlander has a 'hold' function which is the closest to a handbrake- and a P position on the 'gear' stick. I'm curious how they will test it come the MOT in 2.5 years or so.

[Brian Reay]

Although you say below the car has no brake servo, I was thinking to compensate for the loss of the brake servo vacuum with the ign off.

If the car is in neutral it won't lock the wheels.

There can't be many of those around.

[Dave Plowman (News)]

Total bollocks.

The steering doesn't lock until the key is removed.

No handbrake will lock the wheels while the car in is gear.

The answer is to turn off the ignition, but not remove the key. Leave the car in gear. You will still have steering and brakes.

[Dave Plowman (News)]

Care to name the make and model? I've had lots of old cars. None *ever* locked the steering until the key was removed. Including the very first one I had which had been fitted with an aftermarket steering lock in the

60s.

[Dave Plowman (News)]

You can still steer the car with no power assistance. It will just be heavier. But not so heavy you can't steer it to the side of the road. And far safer than trying to stop the car on the brakes while on full power.

[Dave Plowman (News)]

Not so - the engine will be turned by the car moving with an auto until the speed gets pretty low.

[Dave Plowman (News)]

I'd be most surprised if a 'supercar' was over the engine rev limit at 70 mph in second gear.

[NY]

I think very car I've drive with servo brakes, the footbrake has worked far better even with no servo than that handbrake as a means of slowing the car down, as opposed to holding it when it's already stationary.

I was thinking more of simply pressing the clutch - easier to do without taking hands off the wheel while trying to steer round objects ahead, rather than trying to find neutral in the heat of the moment.

No. This was 40 years ago on my mum's Renault 6.

[NY]

With a FWD car, where it's the front wheels, rather than the handbraked rear wheels that are being driven, I can imagine that a really fierce handbrake (which I've never actually encountered) or a really hard yank on the lever could brake the rear wheels while the front wheels are still being driven onwards by the engine. So there is potential for rear wheel skid. As you say, unlikely with most cars' puny handbrakes compared with footbrake with its servo not working because you've turned the engine off.

Exactly.

[NY]

I'd be interested too. I instinctively turned the key just to Accessory, *in case* the steering lock engaged with the key in the off position, but I'm sure it was an unnecessary precaution: when I checked afterwards, the key had to be removed for the wheel to lock.

[Chris Green]

On Citroens (others maybe?) the handbrake works on the front wheels.

[NY]

Yes I've driven my car a couple of miles, including changing lanes, coming off a motorway and going round a roundabout, with no PAS when the fan belt broke. It was heavy. I had to plan ahead and grip the wheel with both hands to get more torque on the wheel, but it was not insurmountable. I wouldn't like to try it in a coach or HGV, though :-)

Is the heaviness of the steering when PAS is disabled due solely to having to compress the PAS fluid on the "wrong" side of the piston that gives power assistance? Or are cars with PAS made with inherently heavier steering (different castor angle) to give greater precision and feedback to the driver, in the knowledge that the PAS will more than compensate for this heavier (but more responsive, more self-centring) steering. I've heard two schools of thought about this.

[GB]

"a bit over 70" - geddit?

This is for the US/Japanese version of the car:

[NY]

Good point. I'd forgotten that. My dad had a couple of Citroen GSs and he said the garage always cursed if they needed to change the discs because they are mounted on the half shafts close to the gearbox rather than next to the hubs, which made it a bigger job.

[Dave Liquorice]

Must have had pretty poor hand (parking..) brakes on your cars. You really didn't want to pull the handbrake on hard in the Dicoverys (but then it's a transmission brake not at the wheel(s). The mondeo would lock up no problems. The current Freelander has an electronic hand brake and IIRC the handbook says nasty things are likely to happen if you manually switch it on when in motion. Most of the time you have no need to touch the parking brake switch, it looks after it, including hill starts.

No key, just a button "Engine Start/Stop", there is a steering lock.

Think I'd just push hard on the foot brake with the car in a high gear and stall it.

[Fredxx]

Obviously it depends on the engine, but most overhead valve engines had a sufficiently heavy valve train that valve bounce would seriously interfere with beathing and limit revs. I am aware of a 1300 Ford Escort where after a prang had the throttle jammed. It wouldn't restart. The valves had touched the pistons and bent. No other damage and worked fine after the valves were replaced.

An old Mini engine above certain revs would make a characteristic clatter, above which there was literally no power and the engine would simply sit there at around 5-6,000rpm.

As soon as ignition modules came onto the market they inherently would incorporate a rev-limiter. There were some aftermarket rev limiters you could add to the old contact style ignition system.