What to do???
Thread Starter
Instructor
Joined: Mar 2005
Posts: 104
Likes: 0
From: West Monroe Louisiana
What to do???
I was driving my 2003 z06 yesterday and all of a sudden it started running like crap. I pulled the codes and the only new code was p 0300 (Engine misfire). It will restart but it has to be above 2000 rpms and is misfire. It was dark and the car was hot, so I plan on checking the spark plugs and wires. If not that, remove the valve covers. What exactly am I looking for? Any pics? I have heard broken valve springs or rods or lifters? Hopefully this isn't an expensive fix. Can anyone give me advice on what to look for?
Banned Scam/Spammer
Joined: Jul 2006
Posts: 2,911
Likes: 10
From: Simi Valley CA
Start simple.. plug wire (s) that may have popped off, connectors to the coil packs, burned wires, cracked plugs. I wouldn't go ripping into the engine until you rule out the topical stuff. Were you racing it or miss a shift?
Melting Slicks
Joined: Jan 2002
Posts: 2,754
Likes: 0
From: Nokomis FL
My '99 threw the same code and acted the same way, 4 valve springs in various stages of breaking. Driving 40 mph and all went to hell at once. Mechanic told me it was probably due to previous over revs and one finally broke. Good luck.
PS, be careful starting it, you might suck a valve.
PS, be careful starting it, you might suck a valve.
Thread Starter
Instructor
Joined: Mar 2005
Posts: 104
Likes: 0
From: West Monroe Louisiana
if it happens to be the valve springs, how could I tell if further damage is done. I'm no mechanic, but am able to take off the valve covers and look. Would this be a good time to get a head and cam package from a decent shop because personally most of our local mechanics I would not trust with anything and would probably charge me out the rear.
Thread Starter
Instructor
Joined: Mar 2005
Posts: 104
Likes: 0
From: West Monroe Louisiana
I changed my spark plug yesterday. I tried to start it and got the same problem. I opened the valve cover and the valve spring closest to the passenger side had cracked. I took out the pushrod and it was straight. I was able to move the valve up and down through the guide and tied it off where it would not fall in. Do I just need to replace the one valve spring? Help!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Tech Contributor
Joined: Jan 2007
Posts: 19,494
Likes: 1,178
From: Dyer, IN
I changed my spark plug yesterday. I tried to start it and got the same problem. I opened the valve cover and the valve spring closest to the passenger side had cracked. I took out the pushrod and it was straight. I was able to move the valve up and down through the guide and tied it off where it would not fall in. Do I just need to replace the one valve spring? Help!
Thread Starter
Instructor
Joined: Mar 2005
Posts: 104
Likes: 0
From: West Monroe Louisiana
what is tdc? and I was planning on replacing one and driving to have someone take care of the rest and maybe get a cam and heads if my wife would let me. Would this be okay if it were done in the next week or two.
Pro
Joined: Feb 2003
Posts: 623
Likes: 11
From: Ankeny IA
TDC = Top Dead Center
Which means the piston for that particular cylinder is at the top of it's travel. You put it in this position in this case to catch the valve and keep it from falling into the cylinder.
Which means the piston for that particular cylinder is at the top of it's travel. You put it in this position in this case to catch the valve and keep it from falling into the cylinder.
Banned Scam/Spammer
Joined: Jul 2006
Posts: 2,911
Likes: 10
From: Simi Valley CA
Pro
Joined: Feb 2003
Posts: 623
Likes: 11
From: Ankeny IA
Or rope. I've always held up the valves with a compressor when I've done it, but feeding rope into the cylinder is supposed to work fine.
I've never tried it, but depending on how far the valve drops with the piston at TDC (can't be much) you may be able to compress the spring enough to get the retainer and keepers on there.
I've never tried it, but depending on how far the valve drops with the piston at TDC (can't be much) you may be able to compress the spring enough to get the retainer and keepers on there.
Last edited by 99C5JA1; Jul 31, 2008 at 05:01 PM.
Thread Starter
Instructor
Joined: Mar 2005
Posts: 104
Likes: 0
From: West Monroe Louisiana
I changed out the valve spring. I borrowed a spring compressor from Autozone for free and used the rope method. The spring was $13 from a local dealership. Everything is running great. Very shortly I want to change out all 16 valve springs. A friend has an A&A Vortech kit that he is taking off of his car in order to sell it. I want to change the valve springs before I purchase it. What should I replace? (Just the springs, or the springs, pushrods, valve spring seals, rocker arms) Any suggestions with an A&A Vortech with the stock z06 cam? Thanks
Pro
Joined: Feb 2003
Posts: 623
Likes: 11
From: Ankeny IA
Replacing the rest of the springs is a good idea. Since you are keeping the stock cam, the stock valvetrain should be sufficient. I would probably upgrade the valve springs to some nice dual springs for insurance and future mod possibilities. I'd also suggest you install some longtubes along with high flow cats to maximize the A&A setup. Remember although the intake air is pressurized, there is nothing helping the exhaust. And the engine's ability to expel the exhaust gases will ultimately limit it's potential (it can't ingest what it can't expel).
