p1518 intake manifold runner control fault stuck open

[swathdiver]

It's not the throttle body. It's the variable length manifold assembly. You may have a hose that's broken or the inside has broken up and isn't moving from low to high RPM setting as it should. On BMW, it's called the DISA valve and they get brittle, break up and mess with the intake valves. On a Ford and many others you have to replace the entire manifold. Don't drive it until you figure it out and correct it.

Are you saying that his plastic intake manifold is cracked or something?

 

[Mudsport96]

It's not the throttle body. It's the variable length manifold assembly. You may have a hose that's broken or the inside has broken up and isn't moving from low to high RPM setting as it should. On BMW, it's called the DISA valve and they get brittle, break up and mess with the intake valves. On a Ford and many others you have to replace the entire manifold. Don't drive it until you figure it out and correct it.

Umm an 03 5.3 has no such thing.

 

[Mudsport96]

Are you saying that his plastic intake manifold is cracked or something?

No, he is referring to the dual runner divider that some of the early 4.3 multi port engines had and some of the ford engines had.

 

[Doubeleive]

It's not the throttle body. It's the variable length manifold assembly. You may have a hose that's broken or the inside has broken up and isn't moving from low to high RPM setting as it should. On BMW, it's called the DISA valve and they get brittle, break up and mess with the intake valves. On a Ford and many others you have to replace the entire manifold. Don't drive it until you figure it out and correct it.

don't think these intakes have anything like that, the variable manifold would be on

• General Motors — 3.9-litre LZ8/LZ9 V6, 3.2-litre LA3 V6, LT5 5.7-litre

 

[Mudsport96]

don't think these intakes have anything like that, the variable manifold would be on

• General Motors — 3.9-litre LZ8/LZ9 V6, 3.2-litre LA3 V6, LT5 5.7-litre

Yes the CPI 4.3 had them to switch from a long runner tune port style intake below 3500 rpm to a shorter single plane type manifold above that rpm. Actually worked ok until the stick then they are either real grunty lowend and fall off or no lowend and pull up top. Would have been nice to see hiw they would have worked with the 96+ heads over the swirlport style heads

 

[Doubeleive]

Yes the CPI 4.3 had them to switch from a long runner tune port style intake below 3500 rpm to a shorter single plane type manifold above that rpm. Actually worked ok until the stick then they are either real grunty lowend and fall off or no lowend and pull up top. Would have been nice to see hiw they would have worked with the 96+ heads over the swirlport style heads

that's all beyond me, I just know these manifolds don't have anything like that based on looking at them and if this was the case it would be noted all over and probably make it impossible to swap intake's from say a ss trailblazer or a 5.3 to 6.0 or 5.3 to 6.2, etc that would complicate things a whole bunch.

 

[swathdiver]

Yes the CPI 4.3 had them to switch from a long runner tune port style intake below 3500 rpm to a shorter single plane type manifold above that rpm. Actually worked ok until the stick then they are either real grunty lowend and fall off or no lowend and pull up top. Would have been nice to see hiw they would have worked with the 96+ heads over the swirlport style heads

I had an LZ9 motor, it was great for what it was.

 

[BentleyArnage]

don't think these intakes have anything like that, the variable manifold would be on

• General Motors — 3.9-litre LZ8/LZ9 V6, 3.2-litre LA3 V6, LT5 5.7-litre

You are probably correct, yet the code remains. I would then default to the throttle assembly.