Slight Engine Knock/Pinging

[baker.0423]

Hi everyone,

So for the last couple of months now i've been getting slight engine knock under load or hard acceleration. I have been filling the car up with 98 octane however this hasn't seemed to alleviate the issue. I'm suspecting that I may have a faulty knock sensor however i'm not entirely sure. If anyone has had any problems like this in the past or can help me out in anyway i'd be greatly appreciative!

My car is a 2009 Ford Fiesta 1.6 Zetec (88kw).

[DZFord]

If you're hearing the knocking, it is unlikely that the knock sensor is faulty. The knock sensor is designed to do exactly that - detect knock, feed that back to the ECU, which will then retard the timing of the spark event.

Knocking can be caused by poor fuel (not in your case, using 98), carbon build up on the top of the pistons (use a bore scope down the spark plug hole), or a lean fuel mixture. Causes of lean fuel trims are vacuum leaks, reduced fuel delivery / fuel pressure (eg. weak fuel pump, restriction in fuel lines, dirty fuel filter) or clogged injectors. I don't think you car has a MAF sensor, but a dirt MAF sensor can also lead to a lean fuel mixture.

[baker.0423]

Thanks for the reply DZFord. Yeah I was kind of hesitant to believe that it may be the knocking sensor. I was actually thinking of giving 'seafoam' a go as I've seen from YouTube channels such as chrisfix that it can actually remove any carbon deposits off of the pistons. I've also contacted my local ford and they said that they will take a look at it. The guy I spoke to sounded surprised as allegedly he had never heard of this happening to these cars.

Cheers!

[DZFord]

Yeah you can try the Motorcraft Upper Engine Cleaner, should be sold at your local Ford spares.

[baker.0423]

*Update*

I tried using a liqui-moly petrol engine intake decarb in attempts to clear off any carbon deposits on the piston heads however came to no luck with the pinging disappearing.

However, I then decided to unplug the knocking sensors (yes there are two of them) and suddenly the pinging has completely disappeared and the car feels to be running much smoother. I am now unsure whether as to replace the knocking sensors or whether it could be something going wrong with the ECU and the knocking sensors communicating...

[baker.0423]

I have now isolated the knocking sensors and have found the pinging occurs when one is plugged in. I have ordered a new sensor and will find out next week whether it fixes the solution. Will keep you posted!

[DZFord]

Great troubleshooting and yeah please do keep us posted

[baker.0423]

The pinging is gone! I fitted the new sensor and now there is no evidence of pinging occurring anymore!