Hello guys, my focus has a what I can only identify as a pinging at high rpm/ high load scenario, also when coming of off stop can be heard slightly, sound is independent of revs, like steel balls in a can. Car has new timing set, almost brand new all of the aux pulleys etc… tried premium high octane fuel with no effect. Also no noticeable power drop while engine pings, no stutter or anything like that. Has anyone solved this, or had the same problem? Thanks in advance.

Timing or coke is the only thing that can cause that.

If higher octane fuel hasn't cured it, just try changing the plugs and leads, then the coil pack, then the Crank sensor

Did it do it before the belt was changed? The head timing may be out

But you are probably coked up

Run on high octane fuel with some decoke additive in for a while and perform a run where you can hold the engine for at least 10 minutes at over 4,500 RPM

Hello Dave, thanks for the reply, the problem was present as long as i have the car (for about 4 years), Changing the timing set didnt help, spark plugs were changed about an year ago, all looked fine and the right color, Crank and Cam sensor were also changed without change. I will try the decarbonization, and will look at the pistons with a borescope? Althoug I would say that my style of driving surely had to loosen some buildup over the years. Could this also be caused by fuel issues? For example dying pump (low pressure) or bad pressure regulator? Injectors were pulled and cleaned (looked fine), Or MAF sensor? 

Early 1.6 sigmas were known to carbon build up and sticking valves

You could have weak valve springs too

So, just drove to get some groceries and trying to record the sound on the way back i did some pulls. first pull in 4th gear up a slight hill up to about 4500rpm when heard engine pinging. Noise remainds me of rattle snake. then second pull up the same hill 4th up to 5k and 5th gear full throttle no pinging. finally third time at second gear full throttle pinged at around 4.5k

Cant be heard either times in the recording 😕

Also, forgot to mention that the car always had problem with unloaded idle, so AC off, headlights off.. idle rpms fluctuate, but engine never dies... when ac compressor kicks in the idle is steady. Replaced vacuum hoses under intake, Idle solenoid valve, cleaned throttle body etc.. but never fixed this too, so maybe it has some connection with this pinging?

Unless the catalyst has collapsed, My MK1 did this (1.8 though), that used to rattle at 3-4,000 RPM

It doesnt really sound like there is something loose banging, its coming to the cabin from the front of the car, while the engine pings during the pull, laying off of the throttle even the slightest stops the pinging immediately. so its throttle dependent even while maintaining same rpm. 

Dave, thank you very much for your help, I would be very thankful for any other ideas that come across your mind regarding this, for now I ordered some decarb additives and will see if that helps.

No worries, let us know how you get on.

Just trying to rule other things out before you have to take the head off for broken/weak valve springs

What number is the high octane fuel available in your location?

95 is regular, 98 premium

18 minutes ago, marek125125 said:

95 is regular, 98 premium

Thanks, that's similar to the UK then.  98 should be enough to stop the pinking in most cars.  I don't have anything further to offer unfortunately.

Hello guys, follow up with this issue: 

I have gone through two tanks this month : first with premium and decarb additive, and then regular with regular additive that i add normally. I think that  the decarb did something, but the pinging is still present, although maybe a bit less noticeable. I would say that it dissapears after the engine is warmed up nicely during longer drive (40-50 km), but its not a rule. Really hard thing to sum up, or to do some consistent tests. 
 

Iam thinking about taking the plastic intake manifold off, taking a look how the ports look, and looking at the pistons with borescope. Spark plugs look consistent and ok color.

Just run on decarb additive for a lot longer and Super (98) just one tank full won't cure it. It'll take a few tank fulls

Make sure you give it loads of revs, holding it over 4,500 RPM for a while

1 hour ago, DaveT70 said:

Make sure you give it loads of revs, holding it over 4,500 RPM for a while

Is that what we used to call an "Italian Tune Up" ?

Oil getting sucked into the Combustion Chambers can cause Pinking.

If it was Fuel related then the Knock Sensor, if your Engine has one, should stop it by retarding the Ignition Timing.