I dont understand why.

I just finished my S4 N/A to S4 J-Spec swap.

I think my BAC valve is faulty cuz it makes a weird sound...

And also my thermo sensor is not plugged in since I dont have a wire from the harness to connect it...If you guys can help me on that one I would appreciate it. BTW, what the use of the thermo sensor? Can a water tempe gaue be hooked up to it at the same time? Like an A/F gauge to the O2 sensor?

Any of those 2 causes can be related to idoling at 1800 rpm?

And what kind of screw driver am I supposed to use to bring down the rpm on the BAC valve? Seem like the head of the crew has been eaten away...

 

First things I would check would be in the throttle body area. Ive seen a few J-specs with sticky butterflies that result in high, but consistent, idle.

Does yours surge at all or is it simply a steady, high idle?

I doubt the temp. sensor issue is related. Is the sensor on the back of the water pump housing plugged in? Or just the one mentioned in the other thread (the one on the very top)?

 

The one at the back of the pump is connected. And since I dismanttled the engine, I'm pretty sure the TB is fine.

Is there a way to test it without removing it?

 

Yep there's a way to test it....

But is the idle solid? or surging?

To test the TB, look at the throttle stop screw. Note its location and unscrew it until there is daylight between the end of the stop and the bracket on the throttle linkage. (approx. less than an 1/8") Now wind the throttle 100% open with your hand, and release it allowing the throttle to ****SNAP*** closed hard. If the gap between the stop screw and the throttle linkage bracket has closed up, then the throttle is sticking open slightly. If the throttle bracket linkage WILL NOT go past its fully closed point, despite the stop not holding it, then the TB is *probably* fine. Edit: you'll also want to make sure that the throttle cable and or cruise cable aren't resitricting the range of motion before you do the test.

But, if your idle is surging at all the TB isn't the problem, which is why I asked the question.

 

Its not. So it must be the TB

 

Well, lets not jump right to conclusions.....check out the TB and report back, Good luck