Had this problem for about a year now, hasn't caused any noticable problem but always wondered what it could be.
Metallic tapping/rattling sound when accelerating up a hill, can't quite make out where its coming from..does not happen any other time.
Don't think its anything loose... if I drive up a hill and take my foot off the gas then the noise stops, hasn't gotten any worse over the last year but what could the possibilities be?
Thanks, Gary.
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From what you're saying, it sounds like the engine is pinking. Are you labouring the engine at all when going up hills? Does it still do it if you change down a gear?
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Sounds like pinking, or pre-ignition. Unusual these days with electronic engine management, but some of the earlier cars have got adjustable ignition timing. What year and model is the Corsa?
JS
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The year is 1999, it is a 1.2 16v.
Whats pinking? Is it fixable/cheap to fix/damaging?
Seems to happen in higher gears a lot more...3rd/4th , low gears only on very steep hills.
Thanks.
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Whats pinking?
www.honestjohn.co.uk/forum/post/index.htm?t=5302
Seems to happen in higher gears a lot more...3rd/4th
Yep, tis pinking by the sounds of it. Not sure if the ignition timing can be adjusted on this engine to reduce / solve the problem. It might be a case of it's all controlled electronically, and non adjustable.
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What petrol are you using? Low octane fuel is more likely to "knock".
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I have filled up with the premium petrol today and so far haven't heard it happen, but I have only done a short drive.
Other than buying expensife petrol is there another fix?
I think my spark plugs need replacing anyway so I have ordered a set bosch super4, do you think this will help or the old plugs be the cause?
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I have filled up with the premium petrol today and so far haven't heard it happen, but I have only done a short drive. Other than buying expensife petrol is there another fix? I think my spark plugs need replacing anyway so I have ordered a set bosch super4, do you think this will help or the old plugs be the cause?
Pinking or knocking is caused when the mixture fires too soon, either through incorrect ignition timing, too low octane fuel or hotspots on the head/exhaust valves which ignite the mixture before the spark timing.
Years ago, it was often a sign that carbon and lead deposits needed removing, indicating the need to remove the head for a decoke.
Using a higher octane petrol would suppress the problem, I once resorted to putting 100 octane into a Hillman Imp until I had the opportunity to do that!
Full throttle in high gears uphill/ low speed would often cause this in the days before cars had 'knock sensors' and electronic control systems to prevent it.
New plugs may improve running under other conditions but I don't think they will entirely fix the problem, a general check on timing and emissions might help find the cause.
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Have you checked for any loose or perished rubber pipes or hoses that may be causing an air leak into the manifold side of the engine and upsetting the fuel mixture. Perhaps something has broken over the past year or come adrift. How does it run generally, cold starting OK? What about idling, is it smooth and no tapping or rattling noises? I think these engines have a timing chain, perhaps it is worn causing a noise itself or it may have let the timing slip out a bit.
What sort of mileage is on the car, is it used for local short journeys as there may be some carbon build up inside making things worse.
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It idles fine, is used a lot for short journeys, has done 90k miles.
Cold starts are generally fine although occasionaly misfires on startup.
Some more info... what I previously thought was a completely different problem but may be related, there is sometimes acceleration trouble where the revs seem to stick at about 2k usually in lower gears and I travel at about 10mph, I can't accelerate no matter how much I put my foot down but after about 10 - 15 seconds the car operates almost as normal again although with a slight loss of power.
Was told this may be due to the lambda sensor...maybe this is letting too much or too little fuel into the engine and causing both of the problems?
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The timing on that engine is set by the engine management and not adjustable, so the problem lies elsewhere. Yes, it may well be connected with the hesitancy problem, but as you'll have seen there are a number of potential causes. I guess the engine management light hasn't shown at any time?
JS
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Many engine managements systems have as an "octane adjust" function that can be set -usually by earthing a wire in the management loom-you would need to go back to the manufacturer to see if this is available on your system.
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