Brief engine knock/cold engine/first couple accelerations@2.8-3krpm
 

Hi,

so I have this issue with my 2012 GT86. It makes some brief knocking noises when accelerating a bit more aggressively with cold engine around 2800-3000rpm and it only does it once or twice per startup. This does not happen when engine is warm.

The knocking sounds like a rod/bearing knock, but also had similar noise coming outta the engine when I had a bad VTT valve (which has been replaces now).

- Only makes the knocking noise on cold start.
- Only makes the noise IF accelerating a bit more aggressively.
- Only knocks with one or two first accelerations.
- Noise comes around 2800-3000rpm
- No fault codes
- Valve rebuild done by dealer
- One VTT valve replaced
- Stock engine
- Some of the intake piping removed (noise generator etc)
- Engine oil Castrol Edge 5W-30

Any help for what could cause the knock would be great, thanks!

Not to be a real downer, but I had this for a few days before my car spun a bearing. I drove the car gingerly until the one time I didn't. My first hard pull over 5kRPM sealed the deal after the dealership had rebuilt my engine (recall woes). They rebuilt it again, same issue within 80 miles.


The car should not be assembled in a way that prevents you from driving it within normal operating parameters. Wait for it to be warm, give it hell and see how it does. Don't settle for the car not being fun to drive; that defeats the purpose. I emplore you to push the car once warmed up and make sure it doesn't lose its shit. Better to have it blow right after a rebuilt than a year later. The more time passes, the more likely they are to say it's not related to the work they've done.


It's highly likely that this is nothing and you're being paranoid. It's also likely that if there is something wrong, it has nothing to do with what they've done. There's no way to know for sure- the only thing you can know for certain, is that the moment you're afraid to drive your car, something needs to change.



Push the car to its limit and find new peace, or find out that there's more work to be done. Don't settle, don't give up, and don't stop loving your car.

Were both rebuilds under warranty?

Here’s an idea. Maybe don’t induce so much load on a cold engine?

I have a feeling the culprit might be the thicker oil you're running.

Thanks for replies guys!

DarkPira7e:
Taken the 86 to the track twice this autumn so yeah I've taken it to the limit. After first time the VVT-valve issue came up and dealership replaced it. After that I had another go at the track and nothing bad came out.

I do suspect that there's something a miss from the last engine rebuild.. Maybe some gunk or.. something in the oil channels making the oil pressure build up slow.. ? Or perhaps there's still some issue with another VVT-valve.

The issue that I have is more of a nuisance than anything else, since the car works fine otherwise. Thou' it does make you a bit paranoid, thinking when is some bearing gonna give up, hehe...

Anyway, the worse that can happen is that the engine blows out.. Not like it's the last engine around :)

Tokay444:
That's what I've been doing. Sometimes the knocking comes anyway even you try to be silkysmoothbutt with it. Also, I usually let the car idle and warm up a bit before I drive unless I don't have the time, which can happen.

Alxtheoreo:
Had the same issue before when I was running 0W-20, and I think it was even worse back then. I switched to 5W-30 cause I've been taken the car to the racetrack.