Just to be sure, check the injector and wiring, and then do a compression test. From there, decide if you want to do a wet test and a leak-down.
This is a discussion on dead cylinder within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I have a blinking check engine light...i got codes scanned and came up with P0301...i have already tired replacing the ...
I have a blinking check engine light...i got codes scanned and came up with P0301...i have already tired replacing the plugs and coil pack. when i disconnect the wire running to the coil pack while the engine is running there is no difference...but if i disconnect any other coil pack it seems like the car will stall...I have checked the coil pack and spark plug and are making sparks...the spark plug for cylinder 1 smells strongly of gas...I dont know what else to check...
spark plug - good
coil pack - good
that else should i check
Just to be sure, check the injector and wiring, and then do a compression test. From there, decide if you want to do a wet test and a leak-down.
WRX Info Links, Courtesy TheJ
I'm mixing the barley with the grape again. Rory Gallagher
Själen är större än världen. Ricky Bruch
Let the liquor do the thinking. Jim Lahey
DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.
how would I check the injectors or do a compression test?
have you tried running fuel system cleaner through the car? since the coil is firing the plug its either a fuel system or compression problem, hence the compression test. you need a compression tester, a tester that threads into the spark plug hole and checks for how much pressure the cylinder is making. be sure to do it on all cylinders as it's best used as a comparison between cylinders.
for the injectors, if the cleaner doesn't help, just disconnect the connector and check it for B+ on one pin and a switching ground on the other.
you could also do, like above, a cylinder leak down test, but those testers are a bit more expensive. basically you put the cylinder and TDC compression (so the valves are closed and the piston is pushing straight down on the crank) and fill the chamber with 90ish PSI. if everything is sealing well the leakage (as read on the leak down tester) will be minimal, like 10%.
Blobeye Syndicate #75
2005 OBP WRX Sport Wagon
Stewart Warner Boost & Oil temp gauges / OEM 20 mm rear bar
Cobb stg 2 / STi uppipe / Crucial Racing downpipe
Stromung 2.5" catless centerpipe / Scooby Sport New Age centre pipe & backbox
Bad compression would not be the case!
You probably have trouble with ignition on that cylinder. Its either a sparkplug or a coil.
You can check it your self. Just screw out sparkplug on that cylynder and conect an ignition coil to the spark plug, make sure that the spark plug will be touching something metal, hold it in your hand and ask someone to turn the the ignition so that the engine would turn, you will probably see the spark flashing. If you don't try to replace the plug (take from other cylinder) if it's still dead the problem is in the ignition coil or wire.
![]()
Actually "bad" compression can cause your problem IF one of the valves for that cylinder is hanging open. Had this happen when I mis-aligned a pushrod, had spark and fuel but no compression to ignite the mixture. Plug came out wet, got specific cylinder misfire code ( not the generic P0300 ), then found the valve hanging open.
Compression test will tell the tale. Possible causes are a broken valve spring or stuck valve. What was going on up to the point the code hit? Any funny noises from the engine bay?
2005 Legacy GT - stock for now
1991 Galant VR4 - Sold
2002 WRX Wagon - Sold
Blobeye Syndicate #75
2005 OBP WRX Sport Wagon
Stewart Warner Boost & Oil temp gauges / OEM 20 mm rear bar
Cobb stg 2 / STi uppipe / Crucial Racing downpipe
Stromung 2.5" catless centerpipe / Scooby Sport New Age centre pipe & backbox
Bookmarks