Silvia Club of NSW

Was getting a returning missfire problem for ages, thought yeah it just the coil packs ill replace them one day.
well i did replace them and the problem went away for about a week. Then i bought a new ignitor which didn't do anything. bought new plugs, that worked for a day. then i swapped spark plugs/coil packs with another cylinder , and still the same cylinder would get the fouled plug.
Did a compression test results are 135,145,140,120.
pour some oil in the cylinder and compression jumps up on all 4.
This motor is about 4 months old.

Cp pistons and rings.
Are cp piston rings crap?

How much would i be looking at for new rings installed?

they shouldn't be stuffed after 4 months. unless you didn't bed the engine in properly when they were fitted,or you ran it hard with low oil pressure,a blocked oil filter or something similar.

replacing rings is a complete tear down job. to do anything other than rod bearings in the bottom end means a full strip down & rebuild. head off,bottom end out and start from scratch.

the block should be honed at the least before the new ones go in as well.

who did the rebuild? I'd be talking to them first,see if they will give you any warranty on the previous work.


Justin...

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STI - Made in Texas,not Japan.

I'm guessing i didn't run it in hard enough.

It was built by duncan foster, i will give them a call tomo.

If its too costly i might just start selling my car in parts. I am not pulling the motor out again, such a pain in the arse job. For a shop alone to do that its $800.
I will never get another built engine again after the headaches i have gone thru with this motor.

Seems that everybody that I know that has an engine built has some sort of issues with it.



That said, I wouldn't think that rings would cause a missing issue unless they are seriously screwed. You might be better off putting it on a dyno (eg Unigroup) and seeing what is going on. It could be a bunch of other issues (eg fuel pump, reg, ecu, afm, etc etc)

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Disclaimer: I actually DO know everything

Sil80 - SR20DET 231rwkw
Silvia Race Nugget - SR20DET 225rwkw
Stagea - DeathWagon - RB25DET 185rwkw.

My Lame Gallery: http://www.toomuchboost.com/gallery/main.php

yes maybe, but it doesnt explain the low compression and the cylinder with the lowest compression is the one with spark plug fouling problem.

Whats it fouled with? Oil or petrol?

Could be leaking/sticking injector?

_________________
Disclaimer: I actually DO know everything

Sil80 - SR20DET 231rwkw
Silvia Race Nugget - SR20DET 225rwkw
Stagea - DeathWagon - RB25DET 185rwkw.

My Lame Gallery: http://www.toomuchboost.com/gallery/main.php

it looks carbon fouled, no oil on the spark plug.

was going to swap injectors around from a good cylinder and test. will do that next.

Just done a leak down test. There is no bubbles from the radiator, so HG is fine. 3 pistons have 15% or less leakage and the other one has 30% you can hear slight hissing sound from the dipstick and oil cap.
Don't think its worth it all to pull the motor down just for one ring.

So are you happy to have a dud motor?

_________________
Disclaimer: I actually DO know everything

Sil80 - SR20DET 231rwkw
Silvia Race Nugget - SR20DET 225rwkw
Stagea - DeathWagon - RB25DET 185rwkw.

My Lame Gallery: http://www.toomuchboost.com/gallery/main.php

no im not happy, but i dont want to spend anymore on it

so try for warranty,that is usually free. seeing as the people you let build it last time either stuffed it up,or you broke it,I'd try and get them to repair it first before just sighing and living with a fucked engine.


Justin...

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STI - Made in Texas,not Japan.

its a tough situation,

keep in mind also that if you live with it, it's likely to get worse

eventually something bad could happen.

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To err is human, but to really fuck things up you need a computer

i called the engine builder and they got me onto a mechanic they are close with to check it out. spoke to him and went thru what i have done testing the motor and he said check the ARF next.
So tomo im getting AFR checked.
Then go from there.

15% leakdown is still regarded as ok?

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1996 180sx
1990 Silvia

here i have copied some text below from a guide on carcraft.com

Let's evaluate each of these leak paths separately. Say your engine measures 30 percent or more for each cylinder, and it's all running past the rings. This is a good indication that your engine is tired and could use rebuilding. But if the leakage number is under 20 percent and most of it's past the rings, then be advised that a rebuild is not going to be worth 50 or perhaps even 20 hp. As an example, on the nitrous small-block Chevy story in this issue, we replaced pistons and rings in the engine (granted the cylinder wall finish was not corrected) and picked up less than 5 hp, the equivalent of just over 11⁄2 percent gain. The point here is that even cylinders with 20 percent leakdown do not represent a major horsepower loss.