Hilux Gasoline Engine Knocking

I've got a 2014 Toyota Hilux with a gasoline engine that's giving me a headache. It's only done 27349 km. Lately, I've noticed a distinct knocking sound, almost like something's loose inside the engine when it's running. I'm also experiencing reduced engine power and a pretty noticeable jerking when I try to accelerate. To top it off, there's some smoke puffing out when I put my foot down, and the check engine light is on. I scanned it and it has stored an error. I'm thinking it might be deposits in the combustion chamber causing pre-ignition. I've tried running higher octane fuel, but it doesn't seem to make a difference. Could ignition timing be off? Or is it piston slap? I'm kind of lost and worried it could be something major with the cylinder heads.

4 comment(s)

Sounds rough. I had a similar issue with my old Opel Astra, though it was a diesel. Same symptoms – knocking, loss of power, and even some smoke. For me, it ended up being excessive carbon buildup causing pre-ignition. Have you checked for carbon deposits? Fuel octane usually won't fix the problem. It could still be ignition timing, but carbon buildup is more likely considering the symptoms. If you have access, try a compression test. How old are your spark plugs?

Thanks for the reply. I haven't done a compression test yet, but I will. The spark plugs have around 20000km on them. When you say carbon buildup, where exactly are you referring to? Inside the cylinders themselves? And how did you resolve the issue on your Astra? Did you end up having to get the cylinder heads cleaned?

Yeah, the carbon buildup was inside the cylinders, on the piston crowns, and around the valves. The buildup reduces the volume of the combustion chamber which raises the compression ratio which then causes pre-ignition. I tried some fuel additives, but they didn't really work. Eventually, I had to take it to a workshop. They cleaned the cylinder heads and valves. Given that you're already seeing smoke and losing power, I'd suggest taking it to a professional before it gets worse. Continuing to drive like this will only cause more damage.

Okay, thanks for the advice. I was hoping to avoid a big repair bill, but it sounds like I don't have much of a choice. I took it to the workshop today. They confirmed it was heavy carbon deposits in the combustion chambers. They ended up doing a chemical clean and walnut blasting to remove everything. Cost me around 425€, but the Hilux is running perfectly now.

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