kagtech

iTrader: (2)

Just recently changed on the LB9 engine the Fuel injectors, Intake Manifold and Runners to the Edelbrock high flo. Once the top end was put back together the engine immediately revs up to 4500 RPM or higher. It was not doing any of this prior to the upgrades.
This is what has been done to find the cause of the problem.
1. Verified that the brake booster hose was connected to the intake manifold, and there are not any obvious signs of it being cracked or broken.
2. Verified that the throttle plate was not sticking open. Either due to a hung or stuck throttle cable, or mechanical damage.
3. Verified that the cruise control cable was not involved in actuating the throttle.
4. Disconnected the TPS
5. Disconnected the IAC

Looking for any ideas as to What is causing this? Whatever help that anyone can provide is greatly appreciated.

'Trust'

iTrader: (24)

Sounds like a vacuum leak. Cracked intake perhaps? MAP sensor plugged in correctly? I would disconnect the plumbing for your elbow cap the TB with a pvc rubber cap that has a small hole drilled in it, open the TB and put a compressor through the hole in the cap and pressurize the motor. Have someone feel for leaks.

87silverbullet

iTrader: (11)

Spray some brake cleaner or wd-40 around the intake. When you here the rpm change you have found your vacuum leak.

kagtech

iTrader: (2)

Thank you all for your input. After further diagnostics the problem was due to timing and a passenger side Header/Y-Pipe exhaust leak.