heavychevy357

UPDATE: See post #22

Hey guys, I am getting a flashing CEL in my C6Z when doing WOT pulls shifting between 6-7k. I'll list the details about the car:

07 C6Z
-heads are fixed(stock castings sent to Texas Speed and they performed their CNC 265cc package/BTR 660 springs, bronze guides, new Valves, milled .020)
-Katech K501 cam
-ARH longtubes w/cats
-B&B Bullets
-MSD intake
-NW 102 TB
-Halltech 103 CAI
-McCleod clutch

only 5k miles on mods. Was tuned by Billy Whatley at Motorsport Technologies Inc. well when going WOT around 6k I get the flashing CEL. Goes away as soon as I get back down to normal speed(speed limit) so only about 10 seconds then it goes away. No loss in power, no hesitation, runs normal afterwards, idles like usual. Now the other day I did have one instance where I was getting on an on ramp and gave it little more than half throttle to get in front of someone and it was accelerating then seemed to hold that power and it sort of "fluttered" then continued on. No drop in rpms. Only done this once. Ran it today 1st through 4th up to 120mph and it flashed the CEL but ran like a raped ape! Runs strong as hell.

New plugs and wires installed. NGK TR6IX and swapped the MSD wires out for a set of OEM wires. Hinson boots on the wires so I know they aren't burned on the headers.

Been talking to a buddy of mine here on the forum (Mordeath) and he seems to think it is a false misfire. Thinks I should get it checked out everntually. I had planned on taking it to Randy Leger @ Ragin Racin this Saturday but really not sure I want to let go of $500 to have it on the dyno. If it's false misfire then it would be wasted money I think.

just looking for some second advice/opinions.

as a side note The diagnostic tool I have won't pick up the code because the tuner removed the ability to store the code saying it would set off the misfire code P0300 at idle if it wasn't tuned out .

thanks
Brenton

Tech

Sounds like they didn't actually tune the misfire table if they disabled P0300. That tuner is a hack.

Michael_D

I do not change missfire settings from stock over 3000 rpm. No reason to.

I think you need to stop the redline pulls to you get this sorted out. You don't even know what code is being thrown, so don't assume it's a random anything. It could be a very lean condition for all you know.

heavychevy357

Good point. Thanks for commenting

heavychevy357

**UPDATE**

Went to Ragin Racin today and had Randy Leger take a look at the tune and make adjustments(needed quite a few actually) and put it on the dyno. It still did the fluttering at 4K rpm and #4 cylinder kept showing a misfire code. Changed that spark plug(which were brand new NGK TR6IX) with another one. Still #4 misfire. Swapped a new coil pack on..#4 misfire. He said to check for a broken Spring. Drove her home and immediately pulled the valve covers. Intake valve spring #4 broken valve Spring..DAMMIT!! So looked at the rest and sure enough #2 exhaust valve Spring broken!

I was told that these were BTR .660 springs. However after looking at the receipt again they are listed as PRC .675 springs. Randy told me he didn't like those springs. So his recommendation are PAC 1208 springs. It'll be awhile as I'm trying to get married this year. Unfortunately she will be sitting in the garage for quite some time now (couple months)

pics below..

rjacobs

Why let a car sit over 200 bucks worth of valve springs... And thats if you do all of them.

OR over 2 valve springs to simply fix the issue.

They might not be the best valve springs but if you know exactly what they are, swap out the two broke ones and motor on until you can afford to swap in the better springs.

heavychevy357

PAC springs are $400 and I don't have the tools to swap out the springs. I was quoted $1k for the springs and installation. I guess I could buy the tools necessary and attempt to do the swap myself. Just worried about installing them all at the proper height etc

HOXXOH

Quote "I'm trying to get married this year. Unfortunately she will be sitting in the garage for quite some time now (couple months)"

I busted up laughing at the way you said that. I just pictured the fiancee sitting on the garage floor with her arms and legs crossed while waiting for you to fix the car.

double06

Well here is another thing they need to do. Since you have factory pistons, your piston to valve clearance is not that big when you put a big cam in it. I would suggest you take it to someone who can do a leak down test on it. Given your situation you may have bent the valve slightly since the spring was not really controlling the valve too well. They will pull both rockers and springs off each cylinder (since the heavy spring will help pull valve closed if it is slightly bent) fill with air if there is substantial leak down (when compared to others) they most likely you bent a valve.

heavychevy357

Haha! I showed her your comment; we both got a laugh out of it!

Michael_D

That's some funny **** right there!

The fiancee must be pretty friggin hot to trump the car for two months. This thread needs pics.........

TXGS507

I had the same vision.....

Dan_the_C5_Man

I think the OP really needs to focus on why the springs are breaking. I would assume a setup problem exists and that should be investigated and resolved ASAP, not just replace the broken parts.

Michael_D

Yah, good idea Dan. Something wasn't happy.

I would not use the PAC 1208's. No need for the loads they will have after getting them set to the correct height, and using OE rockers. If anything, 1206's.

You can get the PAC/BTR kits from many vendors. Usually runs about $375 and comes with BTR Ti retainers, locks, seals and shims. I'm not a big fan of the BTR retainers, but they seam to be working out fine for folks. I'll find out for myself soon enough.......

heavychevy357

Dan could you please elaborate and maybe give some recommendations on what springs, retainers, etc I should go with? I'll be doing the work myself and am capable of it once I buy the proper tools but need to know exactly what I should go with and exactly how I should set it up or at least get an idea of how I should set it up. As far as I could tell these springs were not shimmed any if that means anything as to how they were set up. I'll know more once I start taking it apart

double06

Well first get a spring height checker. There are two options here one is the have retainers that are lowered and your springs are set up correctly if this is ls7 most aftermarket springs are like 1.80 to 1.85 inch or the people that did it before are idiots and your set up height is like 1.90+ on a spring that calls for a set up of 1.82 thus the broken valve spring. Most set ups have lowered retainers or shim. Since you have no shim hope you got lowered retainers.

heavychevy357

Yes this is an LS7. I'll get a height checker and see what they measure at. As for the retainers they are PRC titanium retainers for use with the PRC dual springs

Dan_the_C5_Man

I'm afraid I am more familiar with the single / behive spring options, and I know the generalities of installed height / distance to coil-bind, etc., but that's about it. The good news is we have folks like MD and others that do know the pros and cons of dual spring setups, what works and what doesn't.

You dodged a real bullet here - after you get your setup sorted, go out and play those lucky numbers in the lottery.

double06

You could probably go with either the spring you had before or some of the suggestions here. I am betting that the real problem here was with no shims and titanium retainer (which are fairly thin thus creating more valve height) that these spring were not set up with correct installed height. Go buy the tool you need and do that first - check spring height. I believe LSM makes a great spring removal tool. Does both springs at once. You need an air compressor and a tool to put air in cylinder, spring height checker, and a some type of magnetic pointer to grab the steel valve keepers. If the spring height turns out to be bad - then replace all the springs since who know what damage has been done by now. Good Luck.

heavychevy357

UPDATE!

Got the leak down test kit in the other day and finally performed the leak down today.

Started with the right bank(2,4,6,8) as that was the side with the broken valve springs(#2 exhaust and #4 intake springs). Took CAI off, opened coolant cap and got each cylinder to TDC as I worked on that cylinder. Results are as follows:

#2- 90 coming in/ held @ 87=3%
#4- 90psi/held 88psi=2%
#6- 90psi/held 88psi=2%
#8- 90psi/held 87psi=3%

The test kit said if the air compressor being used is more than 100psi then I needed to set the psi on the gauge to 90psi. Which is the reason I had it set there.




After seeing king all those that good I didn't even bother with the left bank(drivers side) being that there were no broken springs on that side and I was in a hurry to get to the dentist.

So.. point being.. I'll be proceeding with a spring kit swap now. Decided on the PAC 1207 kit. I'll get the LSM tool and the spring kit and a group of shims in various sizes.

Glad the leak down test went well and I don't have any bent valves!

Thanks
Brenton