What Is Causing My P0307 Misfire?!?!?!?
11-30-2006, 05:37 PM
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What Is Causing My P0307 Misfire?!?!?!? I was going down the highway passing cars in 4th at 6,000 rpm and all of a sudden inbetween changes I would get big puffs of smoke come out the back like i blew up when i would go back into 6th. SES lights up for a while then a few minutes later starts to blink. I run the OBDII Scanner and pulls up P0307 #7 cylinder misfire.
1) I replaced the plug. Old plug looked good, only had about 3-5 months of life. cleared the codes and ran engine, still sloppy and puts out P0307 again.
2) Swapped entire coil pack rail with ls1powerhouse's rail. Inspected old pack and looked good. cleared the codes and ran engine, still sloppy and puts out P0307 again.
3) Swapped coil pack #7 pack on my rail with the first one. cleared the codes and ran engine. P0307 DAMN!!!
WHAT CAN I DO NOW??? Seriously people, I need help.
My car is running really sloppy and is smoking like crazy.
How do I run a fuel ingector test on #7?
Do ya'll think it's my valve spring seals? I've put about 16-17K miles since i got the car last FEB.
How can I tell if my seals are bad if I take the valve cover off?
Jerry
1) I replaced the plug. Old plug looked good, only had about 3-5 months of life. cleared the codes and ran engine, still sloppy and puts out P0307 again.
2) Swapped entire coil pack rail with ls1powerhouse's rail. Inspected old pack and looked good. cleared the codes and ran engine, still sloppy and puts out P0307 again.
3) Swapped coil pack #7 pack on my rail with the first one. cleared the codes and ran engine. P0307 DAMN!!!
WHAT CAN I DO NOW??? Seriously people, I need help.
My car is running really sloppy and is smoking like crazy.
How do I run a fuel ingector test on #7?
Do ya'll think it's my valve spring seals? I've put about 16-17K miles since i got the car last FEB.
How can I tell if my seals are bad if I take the valve cover off?
Jerry
11-30-2006, 06:14 PM
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swap injectors and see if that will change cyl misfire code
check compression
you could have carbon on the valve not causing it to seat. leaking valve seal would cause carbon to build up
check compression
you could have carbon on the valve not causing it to seat. leaking valve seal would cause carbon to build up
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12-02-2006, 06:49 PM
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It's Done IT'S DONE. APPARENTLY I mistaked #7 with #8. I did a compression test on #8 thinking it was #7 then I saw the injectors were numbered (DAMN 
!!!!) Which by the way it was hard as hell getting that tool hooked up properly. After the compression test we (my friend Grant) found the problem. I took the plug out and it was GUNKED, It was full of oil and carbon deposits. #8 was inbetween 160 and 180 psi. #7 didn't even brake 30 psi... I'll be taking the engine out next saturday, new piston and rings. Well since the engine will be out.... 
forged/spray or heads and cam?
Really, thanks to all that put their $.02 and info.
Jerry
!!!!) Which by the way it was hard as hell getting that tool hooked up properly. After the compression test we (my friend Grant) found the problem. I took the plug out and it was GUNKED, It was full of oil and carbon deposits. #8 was inbetween 160 and 180 psi. #7 didn't even brake 30 psi... I'll be taking the engine out next saturday, new piston and rings. Well since the engine will be out.... forged/spray or heads and cam?Really, thanks to all that put their $.02 and info.
Jerry
12-03-2006, 01:42 AM
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dang Jerry, I thought your car was a very low mileage LS1! Crap dude, you need to keep your foot out of it sometimes! Good luck with your rebuild! I like the heads and cam idea!
12-03-2006, 09:11 AM
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ok now where you driving around in 4th and stayin at or around 6krpms or were you taking it up to 6k and then shifting? because there is no reason to say in 4th at 6 grand. shift it into 5th and still be right in your power band?!?
12-03-2006, 12:18 PM
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Originally Posted by 68birdls1
ok now where you driving around in 4th and stayin at or around 6krpms or were you taking it up to 6k and then shifting? because there is no reason to say in 4th at 6 grand. shift it into 5th and still be right in your power band?!?
the rebuild is going to be fun! perfect excuse to pull the motor and upgrade!:
12-03-2006, 12:20 PM
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Originally Posted by culhan9
dang Jerry, I thought your car was a very low mileage LS1! Crap dude, you need to keep your foot out of it sometimes! Good luck with your rebuild! I like the heads and cam idea!
Hey I dont drive like the rest of the idiots in Bryan
I have fun but that's at the track. H/C is a good idea huh?!
12-04-2006, 12:59 AM
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well i took of the valve covers and i didnt see any noticeable damage to the springs. Do you think it's a good idea to take the heads off before i do anything else? is there anything in particular i should look for? How do I do a leak down test? Can anybody please tell me how this works exactly? what do i need?
12-04-2006, 01:35 AM
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You need a "leak down" tester. Basics are as follows: All plugs out. Put a cylinder at TDC compression stroke. On a good cylinder you might have to prevent the crank from turning. Thread the hose into the spark plug hole and connect a supply of compressed air. My tester has a regulator where I can dial in the pressure and a second gauge that reads out in percent leakage. You should have quite a percentage with only 30psi compression on #7. Listen for where the air escapes - the dipstick and PCV implies rings, the intake and/or exhaust manifold implies valves. I use 100 psi but have seen articles/instructions from others indicating 60 psi. There are probably others on this site that have used this test for your situation. My oil problem was ultimately due to faulty valve guide clearance and didn't show up with this test. It's a good diagnostic.
