Last night on my way home, I saw an 03 Cobra and a new SS Camaro go by, so I threw them a rev to about 5500 rpm. I thought, I should go play with these guys. I slowed down to a turn around point, put the car in second, and jumped on it to go and catch up.

Right when the car got to 3500 rpm or so the car started hesitating and wouldn't pull without sputtering, and acting up. Idle is fine, and just cruising is fine, but if I take the car up in the rpm's the same thing happens. Sometimes it will act up for a little while after I take it up in the rpm's , and sometimes it will just settle back in like everything is fine.

I was letting it idle just now and was listening to the engine, and think I hear something metal or something rattling around. Could I have broke one of the dual springs that come with the G5X-2 and this is the problem? Is the spring possibly broke causing the valve to float?

Any and all help is appreciated, this is my daily driver and I need to fix or figure out the problem tomorrow. If anyone has an idea of what it might be and can explain it on the phone better then writing it out on here call my cell. (941)-268-6308

Ben

 

It very possibly could be a broken valve spring. I just had a very similar issue.

Things to check
1) Check all plug wires. A burnt wire that shorts out on the headers could cause such an issue
2) Check for intake leaks after the maf
3) Check all plugs for damage. If any of the 8 looks very different, that may be your problem cylinder. The rear passenger one is usually a little more oily though.
4) Pull the valve covers off, look closely at each spring. Try pushing down each retainer and you should be able to tell when a spring is broken.

Jon
http://www.ls1howto.com

 

Thanks jmX,

I checked the wires as soon as the problem occured. All the wires are in good condition. I am going to pull the plugs out tomorrow.
I am almost 90% possitive I heard something unusual in the engine though. It sounded a little like something rattling, and it was different from the usual valvetrain noise.


I also was thinking it could have been bad gas at first after all the rain and storm from Isabel here in NC, until I heard the engine noise.


[Modified by Ben01C5, 7:39 AM 9/21/2003]

 

Could be a bent pushrod ... did you by any chance over rev the motor ?

 

Well, I went with my first suspicion(sp) and was right the second to last valve spring is broken, on the drivers side.

Is it best to buy a new set of springs and replace them all on that side? Or just try and get a couple and replace the broken?

Could the valve be bent as well? Requiring head removal? :cry

I figured out the problem, what now? :confused:

 

If you have a bent valve its very easy to check with a compression test. You should have 180-220psi in each cylinder. I know this from experience because I bent an intake valve and only had 110psi on that cylinder when the others were 215psi.

Compression Test Procedure:
#1 Remove all spark plugs
#2 Unplug connector at the center of each coil pack
#3 Unplug each fuel injector
#4 Screw in compression testor and crank engine over for 6-7 revolutions for each cylinder.

By your explanation it definitely sounds like a broken valve spring though. If you do, its an easy fix. The compression test can also tell you which cylinder has the broken spring too because that cylinder will also be a lower pressure.


[Modified by MTWallet, 9:37 AM 9/21/2003]

 

MT,

Thanks for the reply. I found the broken valve spring, just gonna have to wait til tomorrow to get ahold of LGM to see what we can do about this. I only had the cam and hardware in for 3 months, and 3000 miles.
I have never even taken the car to the track, and don't beat it.

Parts fail though, but it is supposed to happen to the other guy.

 

I hear ya! Glad you found the problem. Be sure to heat cycle the spring (3-4 times) once its installed. Things do happen, especially with cams like ours.

 

You can replace it yourself if you have the right tools... Cricket and I did his car in a few hours by ourselves. :yesnod: So replacing one should take less than 45 min.

VR :cheers:

 

Yeah I feel for ya. The same thing hapend to me with my Cartek 2X package. I broke both of the springs on the #4 intake valve. Mine did bend the valve a little. Be sure that you do a compression test. Let me know how LG handles it, hopefully they will handle it better than Cartek.

 

replace all the springs, it will keep your motor equalized

 

I am a realist, and understand parts will break. At the same time in 3000 miles, and no drag racing or abusive driving, I hope I won't have to pay for this.
Maybe they will have a couple springs laying around the shop they could send.

Will find out tomorrow.

 

I'm sure LG can send you a spring no problem...and maybe even a spare for the future just incase.

Do a compression test...and maybe look around to price a set of headbolts and a headgasket. Maybe LG can even send you a couple of stock valves free...most shops usually have stock valves laying around in a bucket somewhere. If you had to, you could have the head off, replace the valve and bolt it all back up in maybe 4-6 hours. You can install the new valvespring while the head is off. This is probably the best way to go if the compression test doesnt come out good.

 

I am definately going to do a compression test, but will I notice the bend in the valve once I get the spring off? Or could the bend be real slight and throw off the compression.

Having the dual springs really saved me.

 

Did LGM do the work? They are very reputable tuner and damn good one. My guess is if it is simply failure of a part, not due to abuse, they would take care of you.

Keep us posted!

 

this happens with all these radical high lift cams. it doesnt matter who the tuner is, just a matter of time. cant just blame LGM because i know of others also. thats a lot of power for just a cam only car. get it fixed, and go out and look for that cobra and SS again!!!


[Modified by robsvette, 11:25 PM 9/21/2003]

 

I had Norris Motorsports in Fla do the work. They did a great job on the install of everything, and the breakage is not at all their fault. It was just a weak spring.

 

Ben, you will not be able to see or feel the bend from the spring side of the head. Just install a new spring and then check the compression. If it is close to the others then you're fine. :cheers:

 

Will do.

 

Talked to Lou this morning, and he is going to send me another valve spring and a valve just in case it is bent. :thumbs:

I hope this will be the only spring I have a problem with, and am gonna be paranoid whenever something weird happens, or something sounds wrong.

He told me there is apparently a bad batch of springs out, and a couple others have reported this problem, and it is with the dark colored springs, and not the shiny ones.