So, I was driving my FD back on GA-400 from getting gas, going about 55-60, in 5th gear, slowly accelerating, and I heaer a pop. I know it was the intercooler coupling nearest the air intake, and I just replaced it yesterday (albeit not with an OEM part, I just used a Spectre from Adv. Auto, with the hope of being able to get by for a couple of weeks). I decided to trry to limp it home, and I come to a stop at a red light, though only for a brief couple of seconds, and the engine is constantly revving from about 1150-1500/1600 rpms. When I turn in to my driveway, the revs bounce up to about 2300 rpms, and one foot is on the clutch, the other on the brake, and it does it again when I get to the garage. Upon further inspection, the vaccuum line running from the upper air intake (Greddy Airinx system) has a split.

So, what is causing the rev issue? Is this the "Limp mode" I've heard about?
Where can I purchase these vaccuum hoses, preferably somewhere close, just a bit north of Atlanta?
And there's a small, brown piece after the air intake, if I'm not mistaken, which has the Denso logo on it. Exactly what is that?

Thank you very much for your time and assisstance,
-Lane

 

I used to live in your neck of the woods, in Roswell a few years ago but before I got my FD.

Not familiar with that system but any vacuum leak past the throttle body will cause a leak that will give driveability problems.

I don't think so, fix the problem you found and then see what how the car acts and go from there.

If it's just regular vacuum hose, and not the larger curved hoses off the airbox, at any parts store.

In the OE setup there are two of the brown valves on hoses coming off of the airbox. The one that goes to the middle of the turbo Y pipe is the blow off valve and the other one that is connected closer down to the secondary turbo outlet is the secondary turbo charge relief valve.

 

*Vacuum leaks cause high, sometimes loping idle. Fix the leaks and see what you get.
*LIMP MODE is caused when the stock ECU senses a failure in a system that's crtical to engine life and it's ALWAYS accompanied by a Check Engine Light. When in limp mode the engine will start and idle normally. But if vacuum isn't sensed at the intake manifold, timing is retarded and fuel is cut. Simply put, you will have just enough power to 'limp' home, but on flat ground with a tail wind you'll still need 5 miles to reach 55 mph.
*Get a copy of the Factory Service Manual or download a copy for free from the 3rd Gen. section Stickys. That brown part sounds like either the stock blow-off valve or the charge relief Valve.

 

Thanks for the help, guys! Heading to the dealer to get the hose tomorrow. I made a mistake, and it's one of the hoses coming from the upper intake pipe. It's a short hose, with a 90* bend that goes downward. I'll get that fixed and see what happens. If the revs are still bouncing, I'll let you guys know in this post again.

Thanks again,
-Lane

 

Well, I got everything on there fixed, but it's still rev bouncing. While it was warming up, it made a couple of loud "Pssh" sort of sounds that I've not heard before one startup/ warmup. It was fine for a few seconds (~10) then it started rev bouncing again. Any solutions?

Thanks again,
-Lane

 

Sounds like you still have a vacuum leak.

 

Perhaps. From what I've read, it sound like it may be the TPS. Then again, that just seems too coincidental. Also, the revs will no longer drop below ~1900 RPM. And the accelerated warmup system can no longer be disengaged with a small throttle input. However, there is still no check engine light, so I've no clue what the problem is.

 

Vacuum test seems to show that all is well in that regard. So it really does seem to be the TPS... I'm going to try to figure it out tomorrow/ Friday, and adjust the TPS if possible.

Thanks again,
-Lane