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I have a 06 base model. So I added Texas speed prc stage 2 heads, brt stage 2 cam and ls3 injectors with spacers. Installed a wide band for tuning.
First outing everything was going good until my clutch line blew cause it was touching the exhaust. (my fault) Fixed that but this time the car was running a little weird. It would keep going rich no matter how much fuel he pulled.
Come to find out my passenger side 02 fell on the exhaust and melted the side of it. I bought 2 new Denso 02 senors and ohm the wires going the engine harness and they checked good. Now I'm getting a content p0300.
I decided to replaced the spark plug. The old ones had some carbon build up on them so I thought that might be it. But nope the p0300 came back again. At idle the car shakes but not sure if that's because of the cam or misfires?
Also when I tap the throttle the rpm goes up and hangs for a few second then slowly comes back down.
Not sure what could have happen when the first outing everything was running good.
Put a screw driver up to all injectors and they are all firing.
Any help to point me in the right direction would be much appreciated.
Having a scan tool to see which cylinder or cylinders are misfiring would help with a diagnosis and then doing some “swap tronics” would be the next step…swapping wires, coil packs, etc…you can do a “clear flood crank” (foot down on the gas pedal while cranking the engine) and see if it sounds like the engines cranking cadence sounds even and consistent telling you that compression may be ok.
A $50.00 code reader won’t let you see misfires so you’d have to invest a few hundred dollars in a scan tool..there are many different makes and models….Bosch, Autel, Snap-On, Topdon, Launch…you can try disconnecting one fuel injector connector at a time and listen for the RPM to drop…if it drops that cylinder is “contributing”…if no RPM change that could point to your misfiring cylinder or cylinders…the only problem is V8 engines are much harder to notice an RPM change…4 cylinder engines are very easy to see this…maybe your friendly parts store can help if they have one of these scan tools.
A $50.00 code reader won’t let you see misfires so you’d have to invest a few hundred dollars in a scan tool..there are many different makes and models….Bosch, Autel, Snap-On, Topdon, Launch…you can try disconnecting one fuel injector connector at a time and listen for the RPM to drop…if it drops that cylinder is “contributing”…if no RPM change that could point to your misfiring cylinder or cylinders…the only problem is V8 engines are much harder to notice an RPM change…4 cylinder engines are very easy to see this…maybe your friendly parts store can help if they have one of these scan tools.
My scanner was $150. I just found the function on it. Must have missed it the first time. Pretty much all cylinders are misfiring. When I give it some throttle and hold it no misfires.
Can you actually feel it misfiring ??…if you can look at your current misfires I would “brake torque” the engine and see which cylinders are actually misfiring…doubt ALL your cylinders are misfiring…at idle with the engine at operating temp what do your long and short fuel trims look like…it will be a percentage.
Can you actually feel it misfiring ??…if you can look at your current misfires I would “brake torque” the engine and see which cylinders are actually misfiring…doubt ALL your cylinders are misfiring…at idle with the engine at operating temp what do your long and short fuel trims look like…it will be a percentage.
Yes I can view live misfires and misfire history. I can feel it at idle. I'll have to check the fuel trim tomorrow. I wrote down the current misfire history. This was just running it a few time for about 2 minutes each time if that.
1. 99
2. 194
3. 122
4. 97
5. 103
6. 180
7. 110
8. 93
Thought I recorded the live misfire but it didn't take.
Yes I can view live misfires and misfire history. I can feel it at idle. I'll have to check the fuel trim tomorrow. I wrote down the current misfire history. This was just running it a few time for about 2 minutes each time if that.
1. 99
2. 194
3. 122
4. 97
5. 103
6. 180
7. 110
8. 93
Thought I recorded the live misfire but it didn't take.
I’d be more concerned with the current misfires at idle and see which cylinders are counting up.
Is this MAP sensor Kpa of 52 at idle ??…52 Kpa equates to 15.3 inches of Mercury…my engine reads about 34 Kpa at idle !!…your fuel trims are fine…should be plus or minus 10% total trims (short plus long terms) !!….MAF grams/second should be at least the liter displacement of the engine at normal operating temp NO loads…I look at MAP KOEO (key on engine off) first and should be around 29.9 inches of Mercury (14.7 psi) at sea level…all 8 cylinders are still misfiring at idle ??
I have a 06 base model. So I added Texas speed prc stage 2 heads, brt stage 2 cam and ls3 injectors with spacers. Installed a wide band for tuning.
First outing everything was going good until my clutch line blew cause it was touching the exhaust. (my fault) Fixed that but this time the car was running a little weird. It would keep going rich no matter how much fuel he pulled.
Come to find out my passenger side 02 fell on the exhaust and melted the side of it. I bought 2 new Denso 02 senors and ohm the wires going the engine harness and they checked good. Now I'm getting a content p0300.
I decided to replaced the spark plug. The old ones had some carbon build up on them so I thought that might be it. But nope the p0300 came back again. At idle the car shakes but not sure if that's because of the cam or misfires?
Also when I tap the throttle the rpm goes up and hangs for a few second then slowly comes back down.
Not sure what could have happen when the first outing everything was running good.
Put a screw driver up to all injectors and they are all firing.
Any help to point me in the right direction would be much appreciated.
Any cam larger than stock, will need the misfire tables in Diagnostics, maxed out in the idle areas. That should have been done in the tune on the very first reflash among other cam related settings.
Yes that was 52 kpa at idle. Key off is 98 kpa which is about 28.93 inch mercury. All cylinders are misfiring still. misfire range from 7-25 a cycle before the number reset 1-8. The car shakes pretty good.
Any cam larger than stock, will need the misfire tables in Diagnostics, maxed out in the idle areas. That should have been done in the tune on the very first reflash among other cam related settings.
Everything was good until my clutch line melted next to the exhaust. After I fixed the clutch line the drove ok but wasn't misfiring. We went out again to try to finish the tune and it kept going rich no matter how much fuel he took out. Found 1 02 sensor fell out of the clip and on to the exhaust. I replaced both 02 sensor and checked the wiring going to the main harness and it checked good. I'm temped to install the original ls2 injectors to eliminate the used ls3 injectors i bought and the spacers.
I also made my own smoke machine to check for vacuum leak. Didn't see anything.
If fuel trims are less than 10% you don’t have a vacuum leak !!..you must be 1000 feet above sea level with that MAP ??…can your scan tool to a “crankshaft variation relearn” ??…if so try that !!…if I was looking at your car I’d be doing an in cylinder pressure transducer analysis to make sure your base ignition timing and valve timing are correct…hope you put the timing chain on correctly…something is way out of whack !!
If fuel trims are less than 10% you don’t have a vacuum leak !!..you must be 1000 feet above sea level with that MAP ??…can your scan tool to a “crankshaft variation relearn” ??…if so try that !!…if I was looking at your car I’d be doing an in cylinder pressure transducer analysis to make sure your base ignition timing and valve timing are correct…hope you put the timing chain on correctly…something is way out of whack !!
Unfortunately my scan tool does not support that function. We are about 860ft above sea level. Pretty sure I didn't mess the timing up for it would have ran like crap from the start. Its something stupid. Just haven't found it yet.
Unfortunately my scan tool does not support that function. We are about 860ft above sea level. Pretty sure I didn't mess the timing up for it would have ran like crap from the start. Its something stupid. Just haven't found it yet.
Reread your first post so you inferred it was running OK until your clutch line blew so don’t know if that was a few days or months…either way it’s not a “fueling” issue since your fuel trims are fine at idle and that is when it’s misfiring…I’d bring it back to your tuner…I’ve newer seen all cylinders misfire on any type of car…one bank yes but not all cylinders…I’d don’t think the car would even run at all with all 8 misfiring.
I don't know how long the fuel rail should hold pressure but probably after a few hours I decided to check it. It didn't have any pressure. I primed it and let it sit for 30 minutes. It had some pressure but didn't seem like a lot. Think I'm going to go buy a fuel pressure gauge and test it. Been wanting to get one for a while anyway. 😂
Help with code p0300
