LS1 P0302 code help

[leon phelps]

Hello,

have a 65 impala with an engine from a 2002 firebird ls1.

Car rand and drove great. Last use (Nov) drove 120 miles round trip to a car show with no issues.

Started and ran it maybe 5 times this winter.

Today took it out for a ride and got the dreaded check engine on my dakota digital dash.

Hooked up my cheapo scanner from harbor freight and got code p0302. From book and internet search it says cyl 2 misfire.

Long time ago had a problem with the injectors after engine sat, so I replaced the injector with a spare one. Reset computer, drove and code came back. Misfire seems to hit at 2800 rpm to start. Next I replaced the coil with a known good spare coil. Same reset computer and drove got same result. Then swapped both the coil and injector from cyl 4. reset codes and got same code result.

Put a spark tester on the cylinder, ran and saw there was good spark on cyl 2.

Ohmed the plug wire, came back at .08omhs. Same as other plug wires. Swapped wires around. Reset codes, ran and same code.

Removed plug and hooked a compression tester up to all cylinders on left side of engine. All came back same 90 psi, didnt open throttle only cranked shortly.

Thoroughly confused here what to try next.

Any guidance appreciated.

[douglowden116]

Broken valve spring ?

[SMWS6TA]

Broken valve spring ?

Broken valve spring would make noise and fail the compression test.

You've done all the right checks so I'm


Check all conditions that will tripped a P0302 and these came up:

Faulty spark plug or wire -You've checked
Faulty coil (pack) -You've checked
Faulty oxygen sensor(s) - Not sure why this would pop under this code.
Faulty fuel injector -You've checked
Burned exhaust valve
Faulty catalytic converter(s) - Not sure why this would pop under this code.
Running out of fuel Poor compression -You've checked
Defective computer - Hope it's not this.

Read more at: http://w.obd-codes.com/p0302
Copyright OBD-Codes.com


Read more at: OBD-II Trouble Code: P0302 Cylinder 2 Two Misfire Detected
Copyright OBD-Codes.com

[leon phelps]

started to check some other stuff....

have 12v from the pink wire on the injector with key on to the block. have 6.5v across the injector connector with ignition on. The reading is the same for all of the injector plugs.

hooked a noid light up to the injector plug and started engine. light flashed.

hooked up pressure tester to the fuel rail. had 60 psi off and then 60 psi running.

guess I can try a new plug since they are cheap.

I have only front o2 sensors and no catalytic converter.

[SMWS6TA]

I was going to suggest new plug...

I had one that look good, but had a small hair line crack, I only found it when we took the plug out.

What plugs are you using?

[leon phelps]

AC Delco 41-110.

Talked to someone at PSI, the wiring conversion company. Was told to check voltage of pink wire at injector. It was 12v key on. The green wire is a ground. It gave me 6v if I used it as the ground for the red. Was confused, removed two other injector wires and got the same result.

Hooked a noid light up where the injector would be. Started engine. It flickered regularly.

still shaking head.

Took out plug 2 again. Disconnected other coils, put on compression tester and cranked for 10 seconds. Got 190psi.

Put plug back in. Ran engine five minutes. Hit throttle to 3k rpm. Code came back. Reset. revved back up. No miss. No code.

Shook head. Gremlin left the building.