Idle at 4000rpm
02-22-05, 12:44 AM
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Coming with an Fc3 near U
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Idle at 4000rpm
Hey all I just bought my first FC-3 its a 1987 Turbo. Theres just one problem when I start it up it jumps to 4000rpm then just idles there. Any ideas why its ideling at 4000rpm
02-22-05, 02:03 AM
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If it stays at 4000rpm and doesn't drop at all within the first 15 some odd seconds, your air selenoid connected to the BAC valve is jammed open. Take it off, and cap the lines that lead to it.
Assuming that was one of the problems, your car should now idle lower for about 2-3 minutes before the thermowax kicks in on the throttlebody, closing the primary throttle plates all the way. Your idle should drop again. Now your car is in 'regular' idle mode so to say, and it should be at 750. If it is not, get a can of carb cleaner or TB cleaner, and start spraying around the rats nest, if the idle fluctuates, then you got yourself a typical vac leak, and you'll have to narrow down the hose. Spray also at the manifold gaskets, if there is a crack or warp or whatever, then your defenitly going to find out by spraying in those areas.
After you have found all the vac leaks by using the carb cleaner, adjust the timing to make sure that the idle is good, it should now idle at like 750 or 800rpm. If it still does not, it shouldn't be far off, and playing with the BAC idle screw (turbo) or the idle screw/BAC allen screw (NA) should get it at 800.
If its STILL not ideling at stock rpm, then you missed a vac leak, so break out the carb cleaner and spray in areas that you think you may have missed. Of course only check areas that are past the throttle plates.
If your positive that there are no leaks, like 100% sure, then the last thing you can check is the throttle plates to make sure that they are closed. Pop off the throttle body elbow and take a look after the engine has been running for some time. The primary plates should be fully closed.
This is the way im going to be checking for vac leaks once the weather gets warmer. Im sure its fullproof for finding them
at least I hope.
Assuming that was one of the problems, your car should now idle lower for about 2-3 minutes before the thermowax kicks in on the throttlebody, closing the primary throttle plates all the way. Your idle should drop again. Now your car is in 'regular' idle mode so to say, and it should be at 750. If it is not, get a can of carb cleaner or TB cleaner, and start spraying around the rats nest, if the idle fluctuates, then you got yourself a typical vac leak, and you'll have to narrow down the hose. Spray also at the manifold gaskets, if there is a crack or warp or whatever, then your defenitly going to find out by spraying in those areas.
After you have found all the vac leaks by using the carb cleaner, adjust the timing to make sure that the idle is good, it should now idle at like 750 or 800rpm. If it still does not, it shouldn't be far off, and playing with the BAC idle screw (turbo) or the idle screw/BAC allen screw (NA) should get it at 800.
If its STILL not ideling at stock rpm, then you missed a vac leak, so break out the carb cleaner and spray in areas that you think you may have missed. Of course only check areas that are past the throttle plates.
If your positive that there are no leaks, like 100% sure, then the last thing you can check is the throttle plates to make sure that they are closed. Pop off the throttle body elbow and take a look after the engine has been running for some time. The primary plates should be fully closed.
This is the way im going to be checking for vac leaks once the weather gets warmer. Im sure its fullproof for finding them
at least I hope.
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