High-revving problem
Thread Starter
Teching In
Joined: Apr 2007
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High-revving problem I have an '02 LS1 in a '93 RX7. I just finished the swap and it starts right up. It stumbles, idles for half a second, then the rpm's shoot up in an instant. I have let it go to 5K before I shut it down, but I can't figure out what the problem is.
The throttle plate remains closed and the throttle plate sensor checks out. What else could it be??
Thanks!
The throttle plate remains closed and the throttle plate sensor checks out. What else could it be??
Thanks!
+1 for a massive vacuum leak!
Chech the back of the intake to see if the port for the power brake feed is open.
That would be the only thing that could leak enough vacuum to allow that RPM.
If that is not it, maybe the IAC valve is stuck open.
I can't imagine a gasket leaking enough to cause that drastic RPM rise.
Is the IAC plugged in?
Chech the back of the intake to see if the port for the power brake feed is open.
That would be the only thing that could leak enough vacuum to allow that RPM.
If that is not it, maybe the IAC valve is stuck open.
I can't imagine a gasket leaking enough to cause that drastic RPM rise.
Is the IAC plugged in?
Thread Starter
Teching In
Joined: Apr 2007
Posts: 2
Likes: 0
The IAC is plugged in, but I haven't checked the sensor's function yet. It's been too darned hot in central TX!
When it starts, it stumbles a bit like there's a vacuum leak, but I think I've checked them all. I have the two ports on the throttle body plugged (the evap and PCV inlets) and the brake booster port is plugged. The tiny hard plastic vacuum line for the AC vents coming out of the MAP housing (along with the brake booster line) isn't plugged, but I don't think that'd cause the problem cuz it's so small.
My PCV system is open, specifically the two hoses coming out of the rear of the valve covers. But the PCV air inlet coming out of the front of the throttle body (before the throttle valve) and the valve cover area shouldn't affect the cylinders' air intake, right? I mean, they're not connected to the air intake stream, right? So that shouldn't cause the problem.
Are there any other sources of vacuum leak besides the throttle body and the rear of the intake manifold?? I mean, that has to be the problem, right??
Thanks for the help!!
When it starts, it stumbles a bit like there's a vacuum leak, but I think I've checked them all. I have the two ports on the throttle body plugged (the evap and PCV inlets) and the brake booster port is plugged. The tiny hard plastic vacuum line for the AC vents coming out of the MAP housing (along with the brake booster line) isn't plugged, but I don't think that'd cause the problem cuz it's so small.
My PCV system is open, specifically the two hoses coming out of the rear of the valve covers. But the PCV air inlet coming out of the front of the throttle body (before the throttle valve) and the valve cover area shouldn't affect the cylinders' air intake, right? I mean, they're not connected to the air intake stream, right? So that shouldn't cause the problem.
Are there any other sources of vacuum leak besides the throttle body and the rear of the intake manifold?? I mean, that has to be the problem, right??
Thanks for the help!!
