Misfire on #4 !!!!Updated!!!! Broken Valve Spring
 

Well, I was driving down the road and the car sounded a bit different. I received the check engine and service stable track ect. I pulled the code which showed #4 was misfiring. I replaced the spark plug, swapped plug wires, fuel injectors, and coil pack, used sea foam and gas cleaner. The problem stayed on number 4. I guess now I will have to take it to the shop. Any other ideas on what I could do or what it might be? You can see the build list in my sig.

UPDATED

Broken TSP PRC Gold valve spring on the Exhaust side (only been installed for 5 months).

It's compression, fuel or spark. Changing things doesn't necessarily eliminate that option...for example replacing the fuel injector doesn't eliminate that as an issue because it could be the harness or connector that might cause it not to fire etc.

I'd start by doing a compression test on that cylinder and rule that out first. If low compression could be a ring issue or a valvetrain issue.

Good luck.

I got the misfire code when I still had my 6. It ended up only being a software issue. Got a refresh and I was fine, guess GM runs windows.

check the headers make sure that it's stable and then check the headers sensors espically the wires cuz sometime heat will burn them and that happened to me and i fix the problems now the check engine didn't came again .

Well, took it to the shop and my valve spring broke. Glad I used upgraded dual springs, it saved my motor. Now I have to contact Texas Speed about the spring. Spring is rated to .675 lift and I am not even close. When I get new springs in, I will have to check to see if the valve is messed up. If the heads have to come off, I may look at a good port and polish job. I cannot believe I broke a spring and was only at 3000 pm not racing.

same thing happen to me a few weeks ago.i don't think you need to remove the heads. i think there are different test to avoid the head removal.

That's what I suspected based on your mods.

The head does not have to be removed to change the spring. You will need to fill the cylinder with air and then use a valve spring removal tool. It is not a hard job to do. Better that it is #4 and not 7 or 8.

I think he was talking about if the valve needs to be changed or repaired. Then the heads would have to be removed and he would get them worked

i dont think there is such thing called a valve, its a valve part that broke. taking heads off is really only for checking for damage but thats not even required here. you don't need to take off the heads to install a cam plus valve parts or really replace. now if a peace of metal fell into the motor then its a different story, and maybe you want to check the pistons and wall, but even they you should be able to tell before the head comes off.

I think I might have bent the valve. Will not know until tomorrow with the air check. If I bent the valve, the head will have to come off. I only had these springs for 5 months so I wonder if TSP will send a replacement? Should I change all of them? If the head has to come off, might as well get new ported heads I guess. I will have to see how much more it will be.

Uh yeah...there are valves in an LS3....16 of them in fact. If a valve is hurt them the heads have to come off...because the head is probably hurt too.

well i stand corrected, i wasn't 100% sure. but still we both know the question being asked here . do i need to take the heads off to check for damage? which the answer is no.

all the OP knows is the spring is broke. so going by that info and that info alone. valves should not be talked about until we know more info.

That's sucks, I had the same springs. Had a miss in the motor knew something was not right. Well the heads were coming off and sent to TSP anyways. Didn't notice any springs were broken when we shipped them off. Well from what I was told they found a broken spring when they received the heads. This makes 3 of us that had broken springs. Me, you and mikess, my springs were ordered in dec of this last year, wonder if they had a bad batch or what ??? Kind of make me nervous as this is now 3 sets. I know that I don't drive my car that hard or hit revlimiter ect to cause a spring issue. I had maybe 4k miles on those springs at most. Knew something was wrong and told my shop at the time