Need Help - car surging
10-21-2014, 06:34 PM
#1
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Location: Marietta Georgia
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Need Help - car surging
I just replaced my intake gaskets and put it all back together. The engine runs smoother except that it surges. It will rev high and then low enough to almost stall. When i rev engine it takes a two or three seconds to go back to idle.
10-22-2014, 02:12 PM
#3
Le Mans Master
This is one of those areas there many of us have had issues and the solutions are various. They may or may not be your problem.
1) Vacuum leak issues
2) I had this issue and it drove me nuts for about 6 months as I was trying to get the new engine up and running . My issue was resolved by taking it to a known Corvette shop. Turned out I had two injector clips that were bad. Idle would swing like a clock pendulum.... and the swing would get more pronounced higher and then lower until it would die. So, check your injector wires to be sure that they are tight. You could try removing one at a time to see if there is a difference in how the engine is running.
1) Vacuum leak issues
2) I had this issue and it drove me nuts for about 6 months as I was trying to get the new engine up and running . My issue was resolved by taking it to a known Corvette shop. Turned out I had two injector clips that were bad. Idle would swing like a clock pendulum.... and the swing would get more pronounced higher and then lower until it would die. So, check your injector wires to be sure that they are tight. You could try removing one at a time to see if there is a difference in how the engine is running.
10-22-2014, 03:52 PM
#4
This was addressed on the other thread where the same question was ask...
its a vacuum leak. Plain & simple.
When the throttle is opened the ECM sees that. When its closed the ECM will see that as well, BUT when there is STILL un-metered air entering the intake after the Throttle is closed, the engine surges because it is responding to tangible inputs while being managed by electronic inputs....understand? The ECM is being told that the blades are closed by the TPS. BUT, air is still entering and the o2 sensor and others are telling the ECM contradictory information,...so it is having a hard time holding a steady rpm.
Any vacuum leak screws with idle and deceleration BIG time.
Look, there are only a few places to look. The search is limited to what was taken apart.
Get some lite oil or even water and fill each inj hole and run the engine....rev it and see if ANY of those holes are now dry.
Spray water or something around the runner gaskets...
finally, spray around the intake gasket. That's it. You will find the leak.
Another way to pin it down is to look at each spark plug,. the leaky cylinder will be very white....indicating a lean mix in that cylinder.
Again, be SURE that your TPS is set right, and that you do have all the vac lines connected and to the correct fittings. Especially the EGR solenoid vac line...that one MUST go to the TB underside fitting.
Good luck
its a vacuum leak. Plain & simple.
When the throttle is opened the ECM sees that. When its closed the ECM will see that as well, BUT when there is STILL un-metered air entering the intake after the Throttle is closed, the engine surges because it is responding to tangible inputs while being managed by electronic inputs....understand? The ECM is being told that the blades are closed by the TPS. BUT, air is still entering and the o2 sensor and others are telling the ECM contradictory information,...so it is having a hard time holding a steady rpm.
Any vacuum leak screws with idle and deceleration BIG time.
Look, there are only a few places to look. The search is limited to what was taken apart.
Get some lite oil or even water and fill each inj hole and run the engine....rev it and see if ANY of those holes are now dry.
Spray water or something around the runner gaskets...
finally, spray around the intake gasket. That's it. You will find the leak.
Another way to pin it down is to look at each spark plug,. the leaky cylinder will be very white....indicating a lean mix in that cylinder.
Again, be SURE that your TPS is set right, and that you do have all the vac lines connected and to the correct fittings. Especially the EGR solenoid vac line...that one MUST go to the TB underside fitting.
Good luck