How does vacuum advance work in part throttle?
At part throttle, high manifold vacuum moves the diaphragm in the vacuum advance canister on the distributor to add more timing. But at WOT, the vacuum drops to near zero and vacuum advance is removed and the total timing then is established by the initial plus the mechanical advance.
Why do you need a throttle position sensor?
Average rating from 93 customers who received a Throttle Position Sensor Replacement. The throttle position sensor (TPS) is part of your vehicle’s fuel management system and helps ensure that the correct mixture of air and fuel is delivered to your engine.
What does it mean when your car throttles up while driving?
In these cases, the TPS isn’t providing the right input, the onboard computer cannot direct the engine to work properly. When the car accelerates while driving, it usually means the butterfly valve inside the throttle has closed up and pops open suddenly when the driver presses on the accelerator.
How is the throttle connected to the accelerator?
In the old days, there used to be a cable that was connected from the throttle to the accelerator. But now in the technological age, the car’s computer controls when the throttle opens and closes by the feedback it gets about the acceleration of the vehicle.
At part throttle, high manifold vacuum moves the diaphragm in the vacuum advance canister on the distributor to add more timing. But at WOT, the vacuum drops to near zero and vacuum advance is removed and the total timing then is established by the initial plus the mechanical advance.
When is a bad throttle position sensor a warning sign?
Engine won’t idle smoothly, idles too slowly, or stalls If you start to experience engine misfires, stalling, or rough idling when the car is stopped, it can also be a warning sign of a failing TPS. You don’t want to wait to get this checked out!
In these cases, the TPS isn’t providing the right input, the onboard computer cannot direct the engine to work properly. When the car accelerates while driving, it usually means the butterfly valve inside the throttle has closed up and pops open suddenly when the driver presses on the accelerator.
What’s the correct timing for a vacuum advance?
Make sure the vacuum advance connection is removed, and now rev the engine up to around 2,500 to 2,800 rpm. Ideally, the timing now should be somewhere around 34 to 36 degrees to total advance. With 34 degrees of total mechanical advance and 14 degrees initial timing, you have 20 degrees of mechanical advance—14 + 20 = 34.