You know when you have been working on a project for ever, you finally finish and there are those little tiny problems that you just can't figure out wtf they are. Well my project has been done for some time now, but I still can't figure out what the hell the little problem is....

The engine:

b18b1 block
b16a2 head
type-r IM port matched

the car is turboed
inline pro mani
t4 turbo
percision aftercooler
TIAL wg
inline pro BOV
blah blah

The problem:

When the car is started everything is fine, it idles where we set it at 1k until the warm up process is over. Right before it hits mid temp it idles up to 1500, then as soon as mid temp is hit, it idles up to 1800rpms.

The high idle is annoying but not the problem although I think it is directly related, the problem persists when I drive and finally hit boost, the cars idle fluctuates between 1k and 1800k. It also has a problem when I am stopped and begin to let the clutch out and push the gas in where it is idling at 1800rpms I don't push the gas nearly as much but then the rpms do their random idle and it jerks the hell out of the car.


If you unplug the IAC it stops being irratic and idles perfectly (3rd IAC, just on this problem, so it isn't a bad IAC).


Cliffs:
irratic idle

What I have tried to begin to fix:

I have read every thread I could over a 3 month period

new IAC
new TPS

I have tried everything cleaning and replacing wise, minus a new IM. I have checked as many vacume connections as I could possibly find with no luck.

This is begining to be one of those problem that makes me want to not drive my car, and I love the thing.

any ideas of where to look would be greatly appreciated guys.

 

Are you runing a stock Map??

 

No sir, tuned by brian fisher at inline pro. Running Hondata s300.

 

Are you still using the FITV?

I would check for vacuum leaks again. Just hold the throttle open a bit and spray brake cleaner. When it bogs, that's where the leak is.

 

https://honda-tech.com/zeroforum/16

 

I don't want to sound ignorant, but I don't believe the B16a2 head has a FITV.
Anyone veriffy for me?

2000 B16a2 head, 2000 ITR manifold.

Forced induction section is just going to tell me vacume leak all day... thanks though.

The reason I am not leaning towards vacume leaks is when I unplug the IAC, the car runs fine besides for a check engine light, and if it was a vacume leak wouldn't it leak all the time no matter what sensor is plugged or not.

Unless of course the vacume that connects to the IAC is only activated when the sensor is plugged in. is that even possible.

 

FITV depends on what throttle body you use, not the head nor the IM.

IT IS A VACUUM LEAK!


The reason it stops fluctuating when you unplug the IACV is because the ecu is not longer hunting and fighting to keep a steady idle. It is simply constant.

The up and down is the ecu opening the IACV and closing it, back and forth, trying to find the idle. A leak is preventing that.


Also, have you adjusted the TPS correctly?

 

yes TPS is set at .45 when close and 5 at FT.

thank you very much for explaining to me why it is a vac leak, tomorrow is my day to play, so all will be fixed.