Pinking

Don't think it matters. You have to retard the ignition. But I don't know how it is done on your car. Had a similar problem on a Fiat Croma; on this one I could rotate the distributor.

Give it a really good thrashing, from your previous posts it sounds like you don't give it enough welly. Not pinking at high revs is surely better than pinking at low revs, and you'll clean the s**te out of your engine. All that increasing the gaps will do as far as I understand it is make it harder for the ingition system to spark and make matters worse.

If it's just been serviced, mebbe the wrong heat range of plugs has been put in?

Stuart

Don't think so. The heat range has to do with getting rid of the soot, while not burning the electrode. In a service they adjust the ignition advance according to factory tables, not according to the actual pinking, i.e. local conditions. That was what I found with my Fiat Croma, hence I always adjusted the ignition advance myself after a service. You may need to set back the ignition advance.

Peter's been posting about his Sei pinking almost as long as I've been moaning about my Ka's brakes :), so it's not something that's just come up after this service.

Just done it with the last tank of petrol, Optimax too. I've been thrashing it as much as possible, ie. when the engine's warm and I'm not stuck in traffic. It doesn't stop the pinking though. A couple of days ago I can get it at 3000 rpm in 3rd gear on a flat road (approx 36mph). I had been using 4th less often for 30mph too because it seemed to struggle although it seems to be a bit happier now, I think. Until the pinking's sorted I'm going going to be going up to

3000rpm through the gears.

Another thing which I find strange is that when I fill up with petrol (most of the time but not all of the time) my engine performs much better. This happens as soon as the key is turned so I can't see how the petrol can get to the engine that quick. I have been thinking that it may have been psychological but from the last tank of Optimax I'm sure that it's not. The engine made a better sound when it was first started and it felt faster too. The thing that was most noticable though was when I reved it high (30mph in 2nd). Usually the revs rise and then drop as soon as I change gear, but with this petrol the fell slowly. It was a great sound but it went after about 2 days. Was it the age of the petrol? The Optimax had no noticable effect on the pinking.

They're the ones I put in a few months ago, I think the old ones (Fiat ones) were just as bad.

When I first told the 'service man' that I had pinking he said it's probably the timing. I said that it can't be changed (no distributor) and he said there are other ways of changing it eg. spark plug gaps. Are there any other ways to change the timing other than spark plugs, TDC sensor and HT leads (I've got new HT leads).

No, the only things that affect pinking are 1) Compression ratio 2) Petrol type; normal or super 3) Ignition advance.

Has the car always been like that? Has it had head gasket replacement with head skimming? That would increase the compression ratio. What is the mileage?

It's not the petrol. I may have a leaking head gasket though. My dad thinks that it's the rocker box cover leaking because it's too high for the head gasket, but the mechanic thought taht it may have been the head gasket but wasn't sure. The Mechanic cleaned all of the oil off and after running it for a while there was still no oil. He said don't worry about it because it's only minor and changing the head gasket is a lot of work.

I think it has always been like that, but at 35,000 (32,000 when I got it) I wouldn't have expected it to have had a new head gaskett.

30mph in second is not high revs! In most cars that's only about 3000rpm. Keep the throttle fully applied in each gear until you reach the rev limiter (it is fairly obvious when this point is reached), which I suspect will be over 50mph in second gear. If you do this often enough you'll clear out all the carbon that has built up because of your slow driving and your pinking will go away, it won't even knacker the engine. So shut up, drive it how it was designed to be driven and stop worrying about plug gaps and other irrelevant rubbish.

James of Sunderland

That's not thrash> Another thing which I find strange is that when I fill up with petrol

I've heard unleaded goes "off" after a week or two. I suspect this may be psychosomatic though :).

A mechanic ought to be able to tell you if an oil leak is coming from the rocker cover gasket or the head. If he can't, he's either not a very handy mechanic, or he's trying to get you to have a new head gasket. The head gasket would be leaking oil onto the engine below the intake / exhaust manifolds, whereas a rocker gasket leaks above them. Not rocket science, or even blowing up a baloon and letting it fly around the room science... BTW, I had a rocker gasket leaking a bit of oil, and it made for quite significant oil consumption until I got it swapped.

Either way, a head gasket leaking oil shouldn't affect the compression. If it's leaking exhaust gases or oil to water, it's easily checked.

I'm not sure about that, that's what makes the pinking worse. I have to use gentle acceleration or my engine's going to go mad.

I never go on roads with a limit greater than 40mph :-(

It would've been the previous owner's slow driving. I've only just done 3,000 miles and I first noticed the pinking within the first 1000 miles I think.

I'm talking about 2 days! Today I didn't actually notice a difference when I filled up (normal petrol).

Yes, it will pink worst under acceleration from low revs. What he's saying is that you should rev it right up in each gear, drive it hard, so as to clear the cylinders of deposits. The idea is to address the cause, not the symptom!

What car is this again, a little Fiat? These are intended to be driven hard and you won't hurt it. I had an Uno 1L and drove it flat out all the time. It still did 40mpg. Even the handbook, which I still have so I will quote directly, on explaining use of the tachometer, said "The car should not be driven at higher engine speeds [than ~6400rpm]. Although no damage will occur, there is no improvement in performance". This was an OHC engine, though, so if it's the horrible pushrod thing it probably won't rev as high.

I never go on roads with a limit greater than 70mph either but...

In my experience, pinking is at it's worst at wide throttle openings and low revs. Wide throttle openings and high revs should reduce pinking. If you run to the limiter in every gear, you'll be dropping into the next gear at or just below the number of revs where the pinking will be dying off.

You need to go out one day and really give the car a thrashing. Get the engine warm, then burn up £25 worth of petrol, rev it to the limiter before you change gear, change down when you brake to keep the revs high. Running your car this "gently" is going to do it more harm than good. You'll have condensation in the oil and the exhaust, which is bad news for your exhaust and engine. Spending £25 on petrol to go around driving to nowhere for an afternoon might seem like a waste, but I'd be very surprised if it didn't sort the problem and it's cheaper than keep paying people to look at the engine and find nothing. If you do much more than 250 miles on that £25 of petrol you're not hammering it enough.

That would be your slow driving, otherwise you'd have noticed it when you bought it, surely?

It's an 899cc version of the 999cc (1litre) FIRE you had in your UNO.

£5 says your Dad's Astra is a diesel, and hence has much more torque and than your Seicento, so it can tool around happily in fifth at very low speeds. Bear in mind that diesels are in effect constantly pinking, they don't have spark plugs.

If you keep driving around with the engine pinking, you'll eventually knacker the pistons. Replacing them isn't especially cheap, as you might imagine. If you do lots of short journeys, never get the engine hot and never give it any revs, you need to have the car on the high maintenance servicing schedule. It sounds to me like you're getting carbon (coking) in the engine. From what I understand, the carbon creates hot spots within the combustion chamber and causes predetonation.

Nothing should happen to petrol within 2 days. Is the fuel filter ok?