Ever since my engine got rebuild (with new SPEC single plate clutch and NEW manual gearbox) my car is making this squeking noise when it hits 4000 rpm and up or when the engine is under load (inclination of some sort).

With the knock sensor on my PFC monitor screen I see next to no knock noise except when I hit around 4000 rpm or engine is under load. Not constant high knock, just high peaks.

When driving it also seems to hold back the engine and put iit under stress as it feels and sounds like a 4 banger at it's rev limit, just hitting 4000 rpm. Weird.


When i rev the engine in neutral, it revs up fine upto red line, no hesitation. no squeeking whatsoever.

As said above, both clutch and gearbox are brand new, although I have heard of issues with the SPEC brand. other than the strange noise, the clutch is doing fine. No slipping or other weird noises, just at 4000 rpm.

The registrated knock noise is definately coming from the noise I'm hearing as that's the only point when it's registrated. My fuel map is also very rich in vac and boost with an AFR of 10.5 from zero boost and up.

once this noise occurs, the car won't accelerate either, once again, like it's holding back the engine in some way.

Strange is that it doesn't happen when revved freely


By now, I have already replaced about every sensor that is on the engine, injectors, ran through about every possible electrical issue I can imagine.

So for me that is totally out of the question.

I rebuild the engine myself to precision and looking at the vac it's pulling (constant 0.4 bar underpressure at idle, good hot and cold starting and constant wooshing noises when started without plugs) I'm 98% convinced that the engine is healthy.

So... any... ANY tips would be welcome.

My next project is to get the gearbox off and inspect the clutch....