My car is a 2003 type-s tl
I got cel ; p0300, p0304, p0306.

I replaced spark plugs and still got the same codes.

I exchanged the coils of the code problem cylinder with the working coils and got the same code.

Today I did a compression test and most of them are around
120psi.

according to the manual, compression pressure is 135psi
and maximum variation is 28 psi.

Does it mean that compression test was good?

or Is it low? do I need to test more like a leak down test?

thank you

 

did you reset the ECU to clear the codes and reset everything?
pull the clock fuse on passenger end of dash for a minute and reinsert
Must do that when chasing a multi cyl misfire code with each move of a good coil to suspect one

plugs--NGK Iridium? or ngk platinum,, not some cheap stuff? right

Did you buy 1 new coil and test it
have you tried the cheater method of unplugging 1 coil at a time until the rpm doesnt drop slightly- thats the bad one

compression- variation is between the cylinders- if all the numbers were even thats a good sign
Did you have a helper holding the throttle wide open and the battery hooked to a charger- so it had good cranking speed for every cylinders test?
how many revolutions did you do to get a max reading,,~4?
it went up and stayed--not drop?

opened throttle can be the differance in the desired and actual reading you got
redo one cyl to see
you can also put a few drops of oil in the cylinder-crank over 2 times and then ck compression
if it went up the rings are at fault

 

thank you for your repy, 01tl4tl
I didn't reset the ecu. I just erased the code with a obd device and got the same code except p0305 gone.
I used a genuine spark plugs ; ngk pzfr6e-11 ordered from amazon.com

I got a new coil but didn't test it yet because the code is on and off.
THE cel usually doesn't turn on. It turns on for 1 day a week and the next day turns off automatically.
I didn't have a helper. I just took a step on the accel pedal when I cranked 4 times each cylinder. Yes, it went up and stayed.
I didn't try a wet test because the manual doesn't show that.

I think that I am going to try the cheater method and try the wet test.
one question: How can I check whether a spark plug is bad or good?

thank you,01tl4tl

 

it sparks blue,,, but dont be testing the TL that way!!!
high energy ignition coil will zap you and throw you across the garage

either move the new coil from one cyl to the next -reset ecu each time with clock fuse
until it runs better
or remove one coil connector at a time cking for rpm drop

the wet test is just to see if it goes up a bunch,,it should go up a little
Seafoam in the oil cleans rings and restores compression

 

reminder cyl numbering pass to driver rear set 123 front set pass to driver 456