swain2894

Hey I got a stock 2000 civic Si with 180k on the motor that is misfiring, its misfiring on cylinder three. Compression is at 70psi compared to 130 on the rest of cylinders. 4k miles ago I replaced my exhaust valves, head gasket, and resurfaced the head. The rest of the cylinders are all running fine. I replaced the spark plug last night and it ran OK for 59 miles then started to misfire again.

https://i.imgur.com/G6uv6EH.jpg
This is the plug after I pulled it after 65 miles
Open to any suggestions

bungalo101

Did you try a wet compression test?

I have a 99 SI w/138k and I have low compression on cylinder three as well.

I added a little bit of oil to the cylinder and redid the compression test, which shot up. The oil added for the wet test will help create a temporary seal for a bad ring. If you still have low compression then it means your rings are fine and you need to do a leak down test to check for the cause. Could be valves not sealing (i.e. burnt valve), head gasket, etc. but a wet test will at least tell you whether your piston rings are shot.

Strangely I didn't have the problems you described. I drove the car for a few years like this (until a few weeks ago actually). The main issues I noticed was major power loss and some consumption of oil (not enough to warrant adding oil, but would be low when it was time for a change).

slomofo

iTrader: (1)

?

bungalo101

Sorry, not valve stem seals. Those shouldn't be an issue during the leak down test if the valve's are sealing. Valve not sealing in general is what I meant. I.e burnt valve, etc. not sealing the combustion chamber.

Edit: FWIW I found this thread. Similar problems with plugs being black indicating burning oil. https://honda-tech.com/forums/showth...2529442&page=2

swain2894

I add a quart like every 1500 miles. I plan on doing a leak down test tomorrow but never heard of wet compression test

bungalo101

Maybe wet isn't the right word but I could have swore I heard it called that. I added about a tsp of oil to the cylinder with the spark plug out. Then did the compression test again. The small amount of oil will help the seal for doing the compression test if you have a bad ring.

grumblemarc

iTrader: (4)

135psi is minimum healthy compression regardless. Your engine is toast.

swain2894

So I'm looking at a full rebuild huh?

slo blue

It ran good for a bit after replacing the plugs?

sanegb16

iTrader: (2)

Retorque you head if you used arp head studs check compression again

sanegb16

iTrader: (2)

Timings probably off anyways do these first to help you narrow down things

bungalo101

So some more background might be helpful. What prompted replacing the exhaust valves, head gasket, and resurfacing the head?

I'm guessing something was wrong and problems existed before these repairs, which is why you messed with the engine to begin with… If you are lucky it could be as sanegb16 suggested and just a head stud problem. What did you torque the head studs to? Did you follow the proper bolt order?

swain2894

Timing is correct

swain2894

Yes ran perfectly fine the at 50 or so miles after that it started to misfire

swain2894

Okay I'll check that when I get home

swain2894

I had a cracked exhaust valve in this same cylinder (3) so we figured might as well do it since its out. I'll have to double check with my friend since he did the torquing. What should it be tourqed to?

NotARaCist

iTrader: (1)

What you have there is a prime case of dry/wet fouling. That cylinder is done. Given the amount of fouling, your rings are probably toast.

sanegb16

iTrader: (2)

Also is your distributor centered advanced or retarded could cause a misfire but not low compression trying to give you ideas that are free to check

swain2894

Did timing about two weeks ago and it's neither advanced or retarded. Thanks for the suggestion though!

NotARaCist

iTrader: (1)

This is not a timing issue. This is a "the motor is done and needs a rebuild" issue. There's nothing else to it.