Need advice, Weak Cylinder?
04-29-2004, 11:38 AM
#1
12 Second Club
Thread Starter
iTrader: (6)
Join Date: Sep 2003
Location: Burbank, CA
Posts: 793
Likes: 0
Received 0 Likes
on
0 Posts
Need advice, Weak Cylinder? I recently dropped my car off at a reputable shop to have a full dyno tune done after I installed the headers and off road Y pipe. Yesterday a good friend of mine that works for the shop called and told me they thought it had a "weak" cylinder.
On the dyno the car put down 310rwhp with the mods in my signature on the stock tune. On the dyno it has a very noticable motor vibration above 4000rpm like it was miss firing. They have been able to confirm the problem is not ignition or fuel related so it must be mechanical. After pulling the valve covers there aren't any valve springs that are visually broken. The motor has 18,000 miles and does not consume oil (any more so than a normal LS1, less than a half quart every 3000 miles).
A compression test will be done today to confirm there is nothing wrong with the lower end of the motor. The pushrods will also be pulled and checked. I am leaning more toward a bent pushrod/s because i've had a couple 2nd gear into 1st gear mishaps in the past. I never felt the engine vibration before the header install which is odd, and we have also confirmed the headers or Y pipe are not hitting/touching on any part of the car.
Can a bent/broken pushrod cause this kind of behavior? If anyone thinks it may be any thing else, any other suggestions are more than welcome. Thank you very much in advance.
On the dyno the car put down 310rwhp with the mods in my signature on the stock tune. On the dyno it has a very noticable motor vibration above 4000rpm like it was miss firing. They have been able to confirm the problem is not ignition or fuel related so it must be mechanical. After pulling the valve covers there aren't any valve springs that are visually broken. The motor has 18,000 miles and does not consume oil (any more so than a normal LS1, less than a half quart every 3000 miles).
A compression test will be done today to confirm there is nothing wrong with the lower end of the motor. The pushrods will also be pulled and checked. I am leaning more toward a bent pushrod/s because i've had a couple 2nd gear into 1st gear mishaps in the past. I never felt the engine vibration before the header install which is odd, and we have also confirmed the headers or Y pipe are not hitting/touching on any part of the car.
Can a bent/broken pushrod cause this kind of behavior? If anyone thinks it may be any thing else, any other suggestions are more than welcome. Thank you very much in advance.
