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Rb20Det Loud Knock After Spark Plug Change

Leeroy94

By Leeroy94,
in Engines & Forced Induction

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Leeroy94 Enthusiast

Leeroy94

Posted
Posted

I was driving my track car last Friday and my engine all of sudden sounded like a wrx. I took all the spark plugs out to find one had cracked severely. I went down to supercheap and bought 6 new copper plugs (bcfr6es-11) and installed them.

It was hard to start and then once started a loud knocking noise was coming from the engine. So I turned the car off, checked fault codes for engine knock but none came up (5,5 on the ecu light).

I restarted the car and then unplugged each coilpack one at a time to see if the knocking stopped but the revs only decreased and so did the knock. I revved it up to 1500rpm and the knock got faster. Then after about 10 more seconds of idling the knocking stopped and the car stalled.

I then restarted the car again and it was struggling to stay on idle and sounded like it wanted to stall, and eventually it did.

I can post videos of the knock stopping and a video of after I restarted the car.

Please help. I have no idea where to start.

Ben C34 Grand Master

Ben C34

Posted
Posted

Spark plugs dont crack for no reason.

What is your tune like? I will guess and say something has gone wrong and engine has died.

The plugs cracking is an indication of Way too much heat (lean) so engine has pinged to death.

Do a comp test if you like. But the knock means it's dead anyway.

Leeroy94 Enthusiast

Leeroy94

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  • Author
Posted

Mods are:

FMIC

Rb25 turbo

3 inch dump pump

Standard ECU

Compression test is:

Cylinder 1: 125psi

Cylinder 2: 121psi

Cylinder 3: 120psi

Cylinder 4: 125psi

Cylinder 5: 120psi

Cylinder 6: 126psi

Yeah but the car restarted after the knocking stopped. Also the car was running on 5 cylinders when putting it onto the trailer, and then immediately after the spark plug change there's a loud knock out of no where? I'm quite confused.

Leeroy94 Enthusiast

Leeroy94

Posted
  • Author
Posted

I just did another compression test. Cylinder 3 is giving different results.

Test 1 cylinder 3: 120psi

Test 2 cylinder 3: 80psi

Test 3 cylinder 3: 95psi

I'm assuming either what badgaz said, a stuck lifter or, a broken valve spring.

Valve spring would explain the knocking, missing and broad variance in compression results.

Badgaz Experienced

Badgaz

Posted
Posted

i'm pretty sure thats one of your lifters making a racket.... i fixed mine with pro-ma mbl8. i would try a good engine oil flush first, fill with some cheap thin oil...then run another flush...then fill with good oil mixing the l mbl8 with the last litre of oil.

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