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Matt, Mechanical Engineer
Category: Ford
Satisfied Customers: 22764
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Hi, I own a 2008 mondeo 2litre petrol. It has developed a pinking

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Hi, I own a 2008 mondeo 2litre petrol. It has developed a pinking sound when under load. The car only does short runs. Any ideas? Dean.

its possible that the plugs and combustion chamber are bit coked up due to the engine never getting that hot

I'd suggest on the next fill up use some high quality fuel like Shell optimax and give the car some hard work a 20-30 minute drive will do with hard acceleration and some high top speed

if the pinking noise persists then stop and I'd next check that the fuel pressure is OK as there's a little test port on the fuel rail

if you don't have a pressure gauge any fuel injection specialist garage will be able to help

I'd also check for air leaks after the MAF meter , any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

its also worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue

On no account touch the sensor wires with anything physical as they are extremely fragile
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