Pinking

[britpower100]

Hi All,

Another bone question.

I noticed last night that under acceleration from lowish revs at low speeds 60 (ish) below 3000 rpm at 3/4 throttle there was a slight pinking until the revs picked up.

I am running on 97 RON fuel is it just me being lazy and I need to change down or a case of they all do that sir.

I checked the plugs at the weekend and they are fine.

No other running or perceived performance problems.

[macdeb]

NO! don't do it. Back off ignition a bit.

[britpower100]

Noted, strobe out tomorrow.

[SILICONEKID346HP]

Could be a leaking exhaust manifold ,I had that sound under those conditions which turned out to be a leak on the weld on the four in to one .

[Quinny]

macdeb said:

NO! don't do it. Back off ignition a bit.

Agreed.... Don't let it pink... There are few things as destructive to an engine as pinking under load

I have 4 pistons somewhere as evidence

[britpower100]

Will check manifold before getting busy with strobe.

Another thought filled up with Murco high Octane instead of Optimax, are the engines that sensitive to octane rating/fuel quality ?

[Quinny]

Shouldn't be an issue at this time of year..... Pinking is worse in hot temps...
If its pinking just because of a change of fuel, I'd suggest its being run to close to its limit anyway...

You shouldn't really notice a few degrees of timing being adjusted, particularly on the road... I'd rather be on the conservative side, and keep the engine safe...


There are other reasons for pinking, such as carbon build up in the cylinder, low fuel pressure and air leaking into the inlet manifold giving a weak mixture.. . It's not alway down to timing

[Dr Mike Oxgreen]

Quinny said:

Agreed.... Don't let it pink... There are few things as destructive to an engine as pinking under load

I have 4 pistons somewhere as evidence

You are over-stating the danger of pinking/detonation (which are the same thing). Many people confuse pinking/detonation with preignition and believe that they are the same thing, but they are not. You will even hear experienced mechanics confusing the two terms; perhaps you are confusing them yourself?

Preignition will rapidly destroy your engine, but pinking/detonation will not.

Severe detonation will cause damage over time, but it is not an instant failure.

The following article gives a good, detailed explanation about detonation versus preignition:

http://www.contactmagazine.com/Issue54/EngineBasic...

[Quinny]

You may think I'm overstating the issue...... But back in 1999 I had a £2000 bill that says I shouldn't have ignored the tinkling, pinking noise....

[Dr Mike Oxgreen]

Then it was probably preignition, not detonation.



ETA: In fairness, it is sometimes possible for severe detonation to lead to preignition, if for example it causes a spark plug tip to overheat to extreme. But that would have to be more than just a bit of detonation as you're going up a hill.

Edited by Dr Mike Oxgreen on Thursday 12th December 12:32

[Geoff38]

I had this , turned out to be a very worn cam exhaust lobe , it was almost round. Something else to check if adjusting the timing fails to cure it.

[britpower100]

I would have termed this pinking as in a light tinking through the exhaust under acceleration, with so many options I will have a thorough check, if nothing obvious then its off to a rolling road and diagnostics Monday.

[PRTVR]

Could be a problem with the automatic advance and retard, I think there is two systems that control it, one is centrifugal weights and the other works of the vac, you should see a small tube going into the distributor, if you pull the other end off and suck on it you should be able to tell if its working, the vac works on a diafram (spl) this moves the mechanical advance/retard.

[britpower100]

PRTVR,

Thanks for that you where bang on, for some reason the pipe had been kinked and seemed to be sealed, not sure what was going on, but a new section of vacumn pipe and all is well again.

[Sardonicus]

britpower100 said:

PRTVR,

Thanks for that you where bang on, for some reason the pipe had been kinked and seemed to be sealed, not sure what was going on, but a new section of vacumn pipe and all is well again.

That figures trapped vacuum hence over advanced ign timing, and at least you know the vacuum capsule is working and not split

[PRTVR]

britpower100 said:

PRTVR,

Thanks for that you where bang on, for some reason the pipe had been kinked and seemed to be sealed, not sure what was going on, but a new section of vacumn pipe and all is well again.

That's great, and it didn't cost a fortune to fix, always a bonus.

[britpower100]

That was the good part, however as part of general fettling the weekend I replaced the exhaust, ohh dear never put a Chim on ramps without smelling salts.

I can forsee new outriggers over the new year.

I am trawling the posts as we speak for hints tips and advice, at least I was forewarned and factored this into the buy (refurb) price.

[Sardonicus]

britpower100 said:

That was the good part, however as part of general fettling the weekend I replaced the exhaust, ohh dear never put a Chim on ramps without smelling salts.

I can forsee new outriggers over the new year.

I am trawling the posts as we speak for hints tips and advice, at least I was forewarned and factored this into the buy (refurb) price.

Should have checked those pre purchase its well documented no offence like

[PRTVR]

britpower100 said:

That was the good part, however as part of general fettling the weekend I replaced the exhaust, ohh dear never put a Chim on ramps without smelling salts.

I can forsee new outriggers over the new year.

I am trawling the posts as we speak for hints tips and advice, at least I was forewarned and factored this into the buy (refurb) price.

That is a slippery slope you know, once you start looking at chassis porn there is no hope for you.

[rev-erend]

Well worth spending 5 mins retightening the exhaust header bolts though .. they do come undone over time.