Evo_SpeedKing

iTrader: (24)

heres the deal, i have an 03 VIII w/ 63k on the clock. my mods are light (MBC, TBE, Dynoflash, 272's). after my tune for cams i went to the dyno and found that i had lost power, compression test showed #3 was @ 95 psi and 1,2&4 were 155psi. a wet test raised #3 to 150 psi. car doesn't use a drop of oil (went 5k to test theory & no issues), doesn't smoke and runs pretty damn strong. wet test ruled out any valve/head damage. i have noticed a STRONG scent of fuel during oil changes, but thats it. any of you engine builders have a guess? has anyone had this same problem?

CharlieGsanD

iTrader: (1)

ring problems....

DS-03evo

iTrader: (21)

How do your plugs look?

Evo_SpeedKing

iTrader: (24)

plugs look fine, no definative signs of anything wrong. i do keep getting the P300 code, but i'm not sure that has anything to do with the compression issues.

justboosted02

iTrader: (31)

rings are shot on cyl #3. time for rebuild

gear head

iTrader: (3)

If adding oil to the test raises psi then it is rings without a doubt.
The gas you smell when changing oil is from it washing past the rings.

sabastian458

iTrader: (25)

Your tune was/is too rich. I had the same issue last year. I ended up spinning #3 rod bearing due to too much fuel. Hate to say it, but it is time to tear into your engine for a rebuild.

DTM

iTrader: (4)

Almost every stock bottom end evo 8 or 9 will exhibit lower compression in cylinder number 3. Everyone on this forum that has a stock bottom end can do a compression test and post the results. Its a fact. We have found (75% of the time) that even when doing drop in pistons cylinder number 3 was still lower. Proper machining and clearance is needed to bring it to spec.

sabastian458

iTrader: (25)

#3 also seems to have the higher % of spining the rod bearing too.

cpoevo

iTrader: (1)

If you do the compresion test improperly it will give you false results. I have done this 2 times following some instructions on here and the compression was low on cylinder 3 on both cars. When you do the check follow the Mitsu manual instructions. Unplug the crank position sensor which is located on the backside of the valve cover behind the oil filler cap. Unplugging this prevents the injectors and plugs from firing.

bluebyu36

time for some pistons and rods

Evo_SpeedKing

iTrader: (24)

but how low?


ok, so if it is the rings whats the easiest and cheapest way to fix it? i have everything to build a 2.3l including a full motor, but now i don't want to put anymore money into the car then i have to.

Evo_SpeedKing

iTrader: (24)

bump.

BOOSTEZ

iTrader: (1)

Rebuild

DougoeFre5h

Your wet test concluded that your rings are shot on #3. This has nothing to do with the crank sensor being plugged in or not plugged in. If in fact you have decent compression in 1,2, and 4 but not 3 under the same conditions, but THEN a wet tests yields a substaintailly raised compression, your rings are not sealing to that cylinder wall and you need a rebuild. It is however possible that the rings seal just fine under boost, which is when they are pressed into the cylinder wall by the cylinder pressure - this might explain why you arent really burning oil.

Easiest way is to pull the head, drop the pan and pull out that piston only. Check the bore closely and go from there. Might just need a re-ring and deglaze.