madhatter

98 Z28, new engine, TR224 cam, LS6 heads/intake, have not tuned it yet. Would no tune cause only one bank to show random misfire with this cam? We swapped coil packs and the coil harness with another car and still get the same result. P0351, P0353, P0355, P0357

Thanks

edwardzracing

iTrader: (59)

I know this is going to seem like a dumb response, but I'm going to say it anyways. Double check everything!! Be sure wires running from PCM to coil connections aren't messed up. Make certain plug wires are okay. Lastly, make certain the coils aren't backwards. I made this mistake and chased my tail for days wondering WTF. Stupid me, I managed to have the coils backwards on the passenger side so the firing order was all jacked up and I got the same random misfire codes (except mine were for the passenger side). The PCM was obviously commanding the correct order, but the wrong cylinders were firing at the wrong time because of my mistake. Check all that and let us know what you find. Hopefully it's not anything internal like damaged pushrods, or lifter issues. Keep us posted man. Good luck.

Brad

Matiate

I live in North Dakota. I have 2010 V6 3.6L camaro 126000 miles on it. I bought it a year ago. After I bought it, my engine light came on and I diagnised it and it was saying that Misfire 1,3 and 5. Actually I wasn't feeling misfire at
all. But during 1 year, I felt misfire badly couple times for a short period time but then my car was working well again after misfire disappears. However last week, my car really misfired badly and didn't disappear as before . I took it to the dealership and they told me that they didn't find any mechanical and electrical issue such as plugs, coils, injectors, fuel pressure, MAF sensor etc. and they said that carbon was build up intake air valve. They opened the top manifold and cleaned it with the spray. But they told me that the car doesn't misfire as before but still some misfiring happens. They said the code still reads low air flow. Then they said that they might need to open the engine and take the valves out and physically clean it with the brushes etc. but wanted to charge $1800 for that.I didn't have them do that because wasn't sure if it was the real problem. I picked my car up and started to drive, it wasn't misfiring as before but then misfired badly again when it was raining but then turned out well again without misfiring. I have following symptoms,
- my car firstly badly misfired badly when it was cold
it mostly misfire when the weather is cold or raining.
- why is only one bay misfiring (1,3,5) ?
- so when it misfires, why? it is most of the time temporarily bad misfiring , not always happening?
- when my car misfired really badly before taking it to the dealership, my fuel was showing low.
- I tried to disconnect the MAF sensor but it was still misfiring

Now, my car doesn't misfire but I know it will happen again.hopefully u might have some info about this issue.

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G Atsma

I think it is electrical, and due to poor connections which the dealer did not want to bother tracing. Check EVERY ground on or near the engine, plus ANY connection for the cylinders involved.

z28a4

iTrader: (1)

Op, could also be an o2 causing it on that side. Do you by chance have tuning software? Could see if the o2 is flat lined.

tonytone4143

I am going to say o2 sensor. unplug it and drive the it the cmputer will put it in close loop. I am pretty sure t hat is your issue. I just had one at the shop today for the same exact issue.

Matiate

thanks, man . I'm just on the car now. I should just disconnect the connector of O2 sensor. I'll try the one on behind the bank 1. Do I need to take the negative from battery firstly or isn't necessary ? By the way, after taking the connector, should I leave it like at or connect it back ? If you can give some instruction it would be perfect.

G Atsma

Disconnecting the O2 sensor puts in OPEN loop, not closed.

z28a4

iTrader: (1)

Disconnecting the maf also defaults it to olsd, iirc. Sets a code though.

youguessit

If you took the head off they may be a bad head gasket seal (unlikely with mls gaskets) or if your exhaust headers aren't secure this can happen. However i would think you would get a o2 sensor code if there was an exhaust leak. Doesn't hurt to check though.

I just saw it isn't tuned.... check the exhaust flange in the dark to see if you can see light in between the gasket and head anywhere. Also look at it in the light and see if there is a crack in the headers somewhere. Make sure after the header collector is sealed up tight. Keep us posted

samckitt

iTrader: (5)

Is this new engine a cast iron block or aluminum?

Floorman279

iTrader: (11)

Im liking the o2 sensor idea. Could try a cat as well. Also like the exhaust manifold idea. Hopefully u sprayed carb cleaner all over that side and the intake manifold looking for vacuum/air leaks. Hoefully ur ls6 intake isnt cracked but i would think u would get a big fat lean code if its mising 4 cylinders.

Floorman279

iTrader: (11)

Wait, guys the original op posted 8 years ago. The 5th gen v6 guy bumped it up

youguessit

Wow

Matiate

Tony, I haven't found the issue yet and thinking to replace the oxygen sensor on bank 1 pessenger side. I wonder that if it is bad O2 sensor, it wasn't supposed to give error code of it ?The car that had same issue was showing bad O2 sensor fault ? Because mine didn't . And how possible that the dealership didn't understand this issue if it was bad O2 sensor ?Is it possible to give me the number of the guy who had this issue then maybe I can discuss with him as well . In addition if I disconnect the O2 sensor should I black tape the connectors ?
Sorry for bothering u with my questions but I'm really overwhelmed about this issue and wanna solve it ASAP.