knocking noise

[mjeazy4784]

Ok this has just started yesterday, I'm getting a knocking noise at (guessing since I have no tac) 1500-2500 rpm, gets louder the harder you push the gas, then goes away gradually and you can't hear it at all once youre past 3000. The oil is clean still on its first oil change have about 800 miles on it planned on changing at 1000. It seems to be relative to engine speed not car speed. Don't hear anything at all free revving or under light throttle. Any way to tell what the heck is going on?

[themadscientist]

Is it a light or heavy "knocking". tapping a spoon on concrete sound = valvetrain, likely a bled-down lifter.poolball on pool table sound = rod knock.

[mjeazy4784]

a guy I know from a local tuning shop said if it's not doing it at all free-revving and only under load 50% or more it's most likely "spark knock" due to a fuel or timing problem...(?) I know my cars not tuned at all but it's got no wastegate actuator and the timing is spot on. It sounds great reving in neutral. I guess I'm going to try to get the rest of the parts needed to get it tuned and see if thats the problem then. Also going to check out the plugs tmw and see if there OK.

[ca18detpowered]

no wastegate actuator.....my guess is maybe pushing it to detonation?

*shrug* just a shot in the dark.

[themadscientist]

Now think about that for a minute. Knock disappears under a load? That is backasswards. It sounds like maybe a bled down lifter that is pumping up due to the increased oil pressure when you rev it.

[mjeazy4784]

some more info maybe to help... its happening EXACTLY between 35 to 45 mph in 5th gear which translates to 1800 to 2200 rpm. the noise quickly fades out right after. It does happen in all gears oddly enough its worse going up hill and barely audible when going down under the same throttle (???) I do have a boost gauge and it seems to do it if the pressure is equalized or 0.1 bar (which is all it can go up to) 50% or more throttle... It's almost like something is loose and the motor's vibration between 1800 and 2200 makes it do it's thing, and only while in gear. it sounds like a clothes washer when all the clothes are on one side, really quick thud thud thud thud. I don't know but wouldn't a lifter or a rod do their things all the time during neutral, light load, heavy load, high rpm, low rpm and any combination?

I'm going to try to get a sound clip or vid soon

[boost_boy]

The sound of lightly worn rod bearings. Take it apart and check it.

Dee

[boost_boy]

a guy I know from a local tuning shop said if it's not doing it at all free-revving and only under load 50% or more it's most likely "spark knock" due to a fuel or timing problem...(?) I know my cars not tuned at all but it's got no wastegate actuator and the timing is spot on. It sounds great reving in neutral. I guess I'm going to try to get the rest of the parts needed to get it tuned and see if thats the problem then. Also going to check out the plugs tmw and see if there OK.

No wastegate actuator? That really isn't good at all..........

Dee

[mjeazy4784]

whats not good about it? makes it so that it can barely boost. I'm going to see if I can get some lift time tmw and check out the bearings...

[dillz]

any money its your bottom end bearing. on that i bet your rings are fried too

[mjeazy4784]

yet another update. I think I've gotten myself worked up over nothing, the sound seems to be coming from behind the dashboard. If someones driving beside me when the noise is at its loudest (can barely hear it with the window down) they can't hear a thing except exhaust and turbo noises. Doesn't do it free spinning, high rpm, loaded low rpm, oil is still as clean as it was when it went in. I have a set of bearings since they were cheap so when I pull the pan I'll proably plastigage them just to see and replace.

Dee, what is wrong with running no actuator? I can't think of any reason this could possibly do damage? I read of a few people that did this during break in to keep the boost low.

And Captain Doomsayer, ring problems usually result in burning oil, compression loss, and general crappy running, its not doing any of that.

[boost_boy]

If you're running with no actuator, then you have no control over your turbo's performance. You're losing boost for one thing and that is not good because the ecu is expecting increased air, so it can compensate fuel delivery. Running without a wastegate actuator is kind of a waste of fuel because your injectors are still dumping fuel even though the amount of air coming back into the engine is insufficient and this is due to the water temperature sensor's calculations. Pull the plug on your water temperature sensor and see how your car acts! Remember, the afm is a major player here as well, so this engine's computer system is looking for all kinds of data to efficiently run and give you performance as well.

With the stock wastegate actuator and a hose hooked from the turbo to the wastegate actuator, you would be seeing anywhere from 6-9psi of boost which IMHO very safe for the stock fuel system. I mean, it's your engine and if someone you trust told you that you can run without a wastegate actuator, then they really don't want you to enjoy your CA18DET. Just nickel's worth..............

Dee