Hi all, i have a 2001 2.5l xtype automatic that has 130.000km on the clock, and it always knocks when cold engine, like a diesel, not a valve knock, not bearing knock, when warm knocks under heavy accelation( up to 3000 rpm, then it starts to have proper v6 soundtrack), i use 98 octan and i think it had less knock with 95 octan… it doesnt sound like a v6 petrol, had also airleak and now sorted, engine runs nice at idle and drives smooth…maybe it have something to do with the inlet manifold tuning, or even the inlet cam( some sort of 3 stage VTEC). engine oils changed every year and are pure in colour. I thought about exhaust manifold leaks also, and or the engine mounts, has anybody had this or is there a topic of this here already?
Thank you.
JIm.
Does this happen all the time or at certain revs? Does it happen under load (up hill or accelerating) and not when at steady speed. What happens if you shift down and accelerate?
low revs ( all under 3000 rpm) under load when cold its the worsed, just driving under little load and get worse under more load, gets 40% better when up to temp, reving in park, no knock, no ticking nothing, really smooth, i was thinking maybe exhaust is leaking…but this is a knock, like a diesel, crank bearing getting worn maybe, but it would probably not quiet down much even warm engine, i also was thinking about the inlet manifold tuning isnt working, because under 3000 rpm it sounds terrible, over that rpm it starts to sound better,as a v6 should sound, extremly difficult to expland, and even more difficult to do a video…i could try to make a video, oil is clear and i change it (and filter) regular and check level, never under half, doesnt eat much more than normal either (oil), starts really nice even really cold and runs nicely, or my whole exhaust is blocked and isnt breathing propely until higher revs… thanks for showing interest in my matter
Have you ever taken it to a shop and gotten the engine codes read?
Not a clue, but still: what about piston slap - is it worth considering?
Would make sounds when cold; don’t know about high rpm… or load relation.
Exhaust blocked or leak would not make much sense, but faulty sensors or leaks should (…) throw codes.
David
Does it only happen in gear? Could it be transmission or engine mount (load shifting) related then?
Can you retard the spark about 5 degrees? Was your spark advanced for operation at higher altitude and now you are at lower?
Knock is bad. Get this resolved.
P.