Spark Knock?

[22MavXLT]

So when the motor is cold and you apply even the slightest pressure on the gas pedal you can hear what sounds like spark knock. When it's warmed up it sounds normal. My 2.0L eco Maverick sounds the same. Are these lil motors that noisy or is there something else going on? I only use 93 Octane fuel. Now that my wife works from home the Bronco doesn't get driven but maybe once every two to three weeks.

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[Forditude]

Same - my dealer told me it’s probably piston slap and it’s “normal” I only run 93 octane as well. I’m thinking it’s LSPI - I’m switching dealers to get a better diagnosis.

 

[22MavXLT]

I figured someone on here would know. I have never even heard of "piston slap". No matter how you look at it, that don't sound "normal".

 

[Forditude]

Maybe I will have better words when the other dealer gets a chance to look at it - they have been great so far. Will post if I find out anything useful

 

[Fordified1]

I figured someone on here would know. I have never even heard of "piston slap". No matter how you look at it, that don't sound "normal".

Piston slap is a sound generated by the piston rocking in its bore and is more common on a high mileage worn engine. Pistons are aluminum and grow more than iron when they heat up so the clearance closes up as the engine warms up. Turbo engines put an extreme amount of heat into the pistons so therefore they have larger clearances within the bore. On top of that engineers use loose tolerances and piston pin offset to increase fuel efficiency.
I’m not sure that’s what you’re hearing but possible.​

 

[scotman623]

Mine does the same thing, goes away after it warms up…

 

[jasonkosi]

I think these motors are just noisy overall. Honestly after 2 years I’m still not 100% used to it. Mine makes the same noise when it’s cold out, but always goes away once warm. 65,000km and no issues

 

[Fordified1]

When the 5.0 in my 98 Explorer was replaced under warranty in 2000. The new engine was noisier than the original and we were so concerned that we had contact with a Ford rep. He said the engine was sourced from the new assembly line and had been revamped for better fuel economy and the tolerances and pistons had been changed. To relieve our worry, they gave us a 100k powertrain warranty. It lasted over 300k miles and still runs today, though leaks from every seal and gasket lol. It didn’t perform as well as the original but fuel mileage went from 14 to 19, and during that time we were happy for the better mileage.

 

[KABQ]

The cam phasers are notoriously loud on these engines as well. There are a bunch of threads about it.

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