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Bellamachinna · Posted: Wed Jul 20, 2005 12:11 am Post subject: PING noises from engine

Hi...

Im sad...

Today my 16v started making strong PING noises from the engine.
My guess is that the valves are on their last legs. Crying or Very sad

The noise is exatly PING. It does it always that engine is working in effort.
Ex:
Motorway, 5th gear, about 2000rpm, a sligtly uphill, depress a little the accelerattor pedal, rpm starts encreasing, and when it gets to 2500/3000 rpm - PING_PING_PING - Confused

.
If i drop to 4th gear the noise apears but as engine gets to 4000/4500rpm quicker the noise is less annoying... Sad

Seems like detonation noise. (the type of noise that cars made when onwers filled with 95 ron unleaded, and could only use the leaded fuel).

Is my guess correct? Sad

What do you think of this?
P.S.-I use to fill it up with 98 ron unleaded. (16v from 1992 without cat - One of the 16v that used leaded fuel)

Thanks in advance
P.Camilo
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tvatavuk · Posted: Wed Jul 20, 2005 8:44 am Post subject:

Ping the way you described it, sounds like detonation.
You should give it a try with ron 98 or higher you could also add some octane booster.
There can be many reasons for self combusting from low octane fuel, fouling sparks or are to hot (don't cool cyl enough) to problems with timing, gaskets......
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Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

Bellamachinna · Posted: Wed Jul 20, 2005 1:36 pm Post subject:

Hi

I use NGK...can it be from those?
They are hotter than G.Lodge plugs....
Also, forgot to mention that with cold engine, this, doesnt happen.
Only with gauge around 70ºCels., the PING noises apear.
I already use 98 ron, but will swap for BP Ultimate 100 ron...
The strange thing, is that only yesterday, the noises appeared.
My guess would be towards valve seal/ hidraulic tappets, but that was not exactly on my plans, right now.
I could do away with the expense right now...

P.Camilo
_________________
All'interno della mia macchina, vi sedete, tenete sopra e CHIUDETE IN SU...

tvatavuk · Posted: Thu Jul 21, 2005 1:09 pm Post subject:

NGK 6BPRFs or something like that which are platinum are hoter then GLs but are still ok.
For now give it a try with better fuel, maybe it was only fuel with low octane (water or something).
Story about unleaded goes something like this, most of it is produced under 95 octane rating and then at factory aded aditives to rise it's octane. (this applies also to special 99/100 octane fuels.)
Problem with that kind of octane boosting is that high leve of octane rate is hold only for few days, and after about a week or so, that fuel can have even lower octane rating then 95.

If you have extra time you could have a look at spark plugs, maybe there is something on them.
Coolant and oil level are steady?
_________________
Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

Bellamachinna · Posted: Thu Jul 21, 2005 4:13 pm Post subject:

Hi

Removed the plugs this morning (almost 3h work-UFFF Evil or Very Mad

). The NGK`s are black, full of carbon deposits Sad

, but dry

(no oil on them). My car is running a very rich mixture Confused

. Oil and coolant levels are all Ok.
However the oil is already very dirty(black) and will be changed next weekend (Selénia 20K). The coolant (Paraflu), was changed at about 6/7 months ago and remains very, very blue, without any brown gunk in the expansion tank.
Cleaned the plugs with a wire brush, fitted them again, but when test driving the car; -PING_PING_PING- again.
A friend of mine, who runs a mechanical workshop, told me to have a look at the temperature sensor for the ECU. He told me that if the car is running a rich mixture, this sensor was probably the cause, but can a rich mixture cause detonation???-(I always tought that a rich mixture would cause fouling plugs, not detonation...Am i correct????)

Thanks for your patience
P.Camilo
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All'interno della mia macchina, vi sedete, tenete sopra e CHIUDETE IN SU...

gritsop · Posted: Thu Jul 21, 2005 4:30 pm Post subject:

Hi,

Yes the coolant sensor for the ECU can lead to false readings towards the ECU resulting in false adjustments to the fuel intended for the egine to burn.

There is a diagram for this sensor so that you can test it with a multimeter.
It gives approximate values of resistance depending on the coolant temp.

Do you have this diagram?

Regards
_________________
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1991 Alfa 33 1.4 IE
2001 Alfa 147 1.6 Distinctive

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boxertricks · Alfasud Joined: 26 May 2005 Posts: 27 Location: england

hi bellamachinna,

sorry to hear of your problems - if i may add my tuppence:

lean mixture can cause pre-ignition (which you have, precursor to detonation) or actual detonation in severe cases ( not the same thing as pinking/ pinging/ preignition - youd have a dead motor by now if it had got as far as detonating).

rich mixture is usually a good safeguard against detonation, the only way the rich mixture can be causing it is if it extremely rich, and has allowed severe carbon deposits to build up in the combustion chambers (as sounds likely, will be worse if high miles anyway), hence raising the already high compression ratio and causing preignition.

the more you drive it like this, the worse it will get - you may need to do a decoke now sadly. it is still possible you could get the mixture sorted, and then blast the carbon out with the help of a cleaning agent fuel additive; but in truth would prob benefit from a head off decoke now, the carbon will affect valve sealing and maybe gum a ring up if it is that bad.

hope you get it sorted, good luck

Guest · Posted: Fri Jul 22, 2005 4:23 pm Post subject:

Hi all...

Gritsop wrote:

Bellamachinna · Posted: Fri Jul 22, 2005 4:24 pm Post subject:

That was me above...
P.Camilo
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All'interno della mia macchina, vi sedete, tenete sopra e CHIUDETE IN SU...