VS V8 bad idle and gutless

[VNCommyBeast]

Hello
Got a VS V8 now after ditching my V6 and it has a terrible idle. Codes come up with a vacuum leak. I've replaced inlet manifold gaskets. I hear a horrid noise coming near the front of the engine AFTER replacing the gaskets. High pitched scream. Have tried blocking all the vaccuum lines, the only one that made a difference was the fuel pressure regulator, for obvious reasons. None others did anything. Idle goes up and down up and down almost all the time in idle. After driving up my big hill it doesn't do it though. Also have quite a good oil leak near back of engine if this is related. Any advice would be awesome. Chur

 

[BlackVXGTS]

Manual or auto? If it's a manual, try replacing the TPS (if it's an auto and the TPS is an issue you will potentially have other symptoms as well such as harsh gear changes, especially 1 -> 2).

 

[VNCommyBeast]

Thanks for your reply. It's an auto, don't have harsh gear changes but will try taxing the TPS off my other car and see if that does anything. Codes come up saying vacuum leak though =( but i'm hopeful

 

[BlackVXGTS]

Hope the info below from the Holden Service manual helps:

The purpose of DTC 36 is to indicate a vacuum leak that is causing idle speed to be out of its controllable limit. Idle speed control is accomplished by means of a closed loop control algorithm, based on actual engine RPM and desired RPM. When these two values disagree, extend or retract pulses are issued to bring idle speed under control. When engine idle speed is greater than desired RPM and IAC steps are at the maximum extended counts, retract pulses are commanded to the IAC motor. If engine RPM responds by increasing a specified amount within a specified time period, the IAC motor is working and DTC 36 is set. DTC 36 test is run every 200 milliseconds.

The vacuum leaks include the MAP sensor junction, PCV hoses, PCV valve, brake booster hose, the fuel pressure regulator hose, throttle body, intake manifold gasket and throttle body minimum idle adjustment. DTC 36 detects a leak in any of these places which may cause the idle speed to rise above the control of the IAC system. DTC 36 is detected when engine idle cannot be reduced by the IAC motor and the IAC is determined to be working.

 

[VNCommyBeast]

Thank you very much for that, it was helpful until i checked my codes again and 36 is gone and won't come back! I'm thinking the new inlet manifold gasket dealt with the vacuum leak and now am still having trouble with the TPS. I'll change that around in the weekend and see how i go

 

[VNCommyBeast]

Ok took the throttle body off the other car and put it on but still no good. Plenty of power now but still idles bad and stalls when i put it in reverse or drive. Gr. Any other suggestions mate