Misfire in a LS3

[376camaro]

I have a 2010 camaro ss LS3, I took it to my garage to get a transmission and differential oil changed along with a combustion chamber clean (usually the check engine light goes on after the combustion chamber clean because we must disconnect the air box, along with the mass air flow sensor, to spray the product in to the throttle body). However, my check engine light did not go on, but we decided to plug it to the scanner anyway and take a look at the readings. We found that cylinder 1-2-3-6 were misfiring once and a while, at idle and at 2000 rpm. My car has 14 000 miles and I drive it, I don’t abuse it but I drive it! So I figured it is to be expected due to were and tear, so I changed all eight spark plugs, now my car is still misfiring but not as often, it will misfire 2 times at 2000 rpm, once every 2 minutes. These is no check engine light on and no DTC’s to be read, I do not think that this should be happening, my car is stock and I put the original spark plugs on. I will be taking my car to the dealer on Monday. But can anyone help me out before Monday, because I am a little puzzled by this (and worried) and I am going for a tune in a few weeks so I want to make sure that my car is 100% before I get the tune done.

Thank You

[JLE58]

please explain this " combustion chamber cleaning" and what are they using to do this?
Is this car 100% stock?
if not what have you done?
IMO a stock car shouldnt need the spark plugs changed at 14k and most of these injector and/or intake cleaners are a hoax and can cause more problem than help.

[376camaro]

Originally Posted by JLE58

please explain this " combustion chamber cleaning" and what are they using to do this?
Is this car 100% stock?
if not what have you done?
IMO a stock car shouldnt need the spark plugs changed at 14k and most of these injector and/or intake cleaners are a hoax and can cause more problem than help.

I don't have the brand name of the cleaner, but it is an aerosol can that simply releases the carbon build-up on the valves. My car is 100% stock, the only thing not stock is my Hurst short throw shifter, which is irrelevant to the problem. My spark plugs did not need to be changed they were still good but they were used, that is why I changed them

[csjcsj]

Seafoam!??? They have an aerosol you spray into the throttle body, but you attach the filter tube back up before hand!

[376camaro]

Originally Posted by csjcsj

Seafoam!??? They have an aerosol you spray into the throttle body, but you attach the filter tube back up before hand!

I really can't remember but I will get the brand name tomorow because I will be going back. But I really think that this is irrelevant, having a misfire has nothing to do with cleaning out a combustion chamber.

[Synner]

Stock spark plug wires are known to get internal damage when you take them off which causes those symptoms. I also had a car where a bad ground and bad battery terminal caused misfires and the codes read as a bad coil.

From the symptoms I would consider electrical problems/connections first.

[Synner]

Or possibly a vacuum leak if the tech didn't reconnect something.

[csjcsj]

Originally Posted by 376camaro

I really can't remember but I will get the brand name tomorow because I will be going back. But I really think that this is irrelevant, having a misfire has nothing to do with cleaning out a combustion chamber.

I actually poured the seafoam in my Mustang via a vaccumn line, and it fouled one of my plugs #4, I know you changed them, but just wanted to state, it will foul a plug!

Don't know why yours is still missing!!!!! Just giving my story!

[cdn2usa]

What kind of carbon build-up did you think you would have on an engine with 14K on it? You even admit to driving it hard.
Typical case of Don't fix what ain,t broke.

[376camaro]

Originally Posted by Synner

Stock spark plug wires are known to get internal damage when you take them off which causes those symptoms. I also had a car where a bad ground and bad battery terminal caused misfires and the codes read as a bad coil.

From the symptoms I would consider electrical problems/connections first.

Thank's I wil check that out!

[376camaro]

Originally Posted by Synner

Or possibly a vacuum leak if the tech didn't reconnect something.

everything is connected under the hood, and we did not remouve anu vaccum hoses.

[376camaro]

Originally Posted by cdn2usa

What kind of carbon build-up did you think you would have on an engine with 14K on it? You even admit to driving it hard.
Typical case of Don't fix what ain,t broke.

I know that there is not significant carbon build in on my motor, but every year when I take the car out I do this combustion chamber clean, I believe that these little thing are simply preventive measure that will extend my engine's life. I am not trying to fix something that is not broken, my car is misfiring, it is a fact. I am trying to figure out why and then fix it before it becomes worse. Unless misfire’s are normal?

[IndeedSS1]

Originally Posted by 376camaro

I have a 2010 camaro ss LS3, I took it to my garage to get a transmission and differential oil changed along with a combustion chamber clean (usually the check engine light goes on after the combustion chamber clean because we must disconnect the air box, along with the mass air flow sensor, to spray the product in to the throttle body). However, my check engine light did not go on, but we decided to plug it to the scanner anyway and take a look at the readings. We found that cylinder 1-2-3-6 were misfiring once and a while, at idle and at 2000 rpm. My car has 14 000 miles and I drive it, I don’t abuse it but I drive it! So I figured it is to be expected due to were and tear, so I changed all eight spark plugs, now my car is still misfiring but not as often, it will misfire 2 times at 2000 rpm, once every 2 minutes. These is no check engine light on and no DTC’s to be read, I do not think that this should be happening, my car is stock and I put the original spark plugs on. I will be taking my car to the dealer on Monday. But can anyone help me out before Monday, because I am a little puzzled by this (and worried) and I am going for a tune in a few weeks so I want to make sure that my car is 100% before I get the tune done.

Thank You

My car misfires on random cylinders at random times, but not enough to set a code. I posed the misfire question on the HPTuners forum. One of the guys that that works for GM in the ECM dept said this was normal for the LS3. I'm confident in this person knowledge and have accpeted his answer. I would have never known about the misfires until I scanned. Not sure how many you will find here that scan their cars...yet.

I too was worried since my last car (Impala SS) had no misfires even at 12 psi of boost.

As I understand it tuning will help.

[376camaro]

Originally Posted by IndeedSS1

My car misfires on random cylinders at random times, but not enough to set a code. I posed the misfire question on the HPTuners forum. One of the guys that that works for GM in the ECM dept said this was normal for the LS3. I'm confident in this person knowledge and have accpeted his answer. I would have never known about the misfires until I scanned. Not sure how many you will find here that scan their cars...yet.

I too was worried since my last car (Impala SS) had no misfires even at 12 psi of boost.

As I understand it tuning will help.

Yup, it sounds exactly like what my car is doing. I recently bought the GM service manual and when looking up misfire in the diagnostic section of the manual I found a dozen reasons’s why it might misfire. However, it stated on page 9-391 of volume 2 under circuit system verification; “Observe the cylinder 1-8 current misfire counters with a scan tool. The current misfire counters should not be incrementing. Random misfires that are not steadily incrementing may be normal." With that said, you and your GM tech might be right. But I personally can’t understand how a misfire on an LS3 block with 14000 miles on it could be part of the normal operating procedure?