FIAV (coolant bypass) on 90 TB

[abakja1]

Has anyone ever tried doing the Fast Idle Air valve blockoff on an older 89-90 throttle body (different than the 92-94 TB like at VFAQ page),...

I have a 90 GSX made in March 1990 so this is the TB I have with all the sensors,..I have a used 92 TB, but have to get an ISC and new TB seals too,...So I was wondering if I could save all the hassels and blockoff the FIAV on the older TB?

The passages on a 89-90 TB look different compared to the 92-94 TB like the one pictured at the VFAQ page and the passages are much larger on the 89-90 TB.... I was thinking I could bypass the hot air by blocking off the hole near the throttle plate at the intake side of the the TB on my 89-90 TB,...

thanks
Kevin

 

[FL_TSi]

I am curious abou this also.
I took TB of to clean it and figured I would do this while I am at it.

Any ideas?

 

[DSMJim]

This is a pointless mod and does nothing for performance at all. All it will do is cause you to have a weird idle and no 1500rpm warm up.

Some people swear by this mod saying their air is cooler, but I tested it hooked and unhooked with a infrared thermometer and the throttle body was exactly the same temperature (well with in a few degrees for a small given variance) but there was no temperature drop of even 10deg so it's pretty well a total waste of time.

Leave it hooked up.

 

[FL_TSi]

I ended up leaving it hooked up.
I wasn't going to byppas it for performance reasons, just for less hoses and cleaner engine bay.

 

[beat90tsi]

The 90 TB is clearly much different than the 91-94 units, and I'm interested in knowing how to block off the fiav on my 90. I don't care about dropping my intake temps by 1/16th of a degree, I'm just sick of my car idling at 1500 for 10 min every morning and I like to simplify the underhood area anytime I can.

Has anyone has successfully done this on a 90?

 

[thegreatms]

I tried to do some thing like this. My ISC was acting wierd and i didn't want to bother it anymore. I wanted to block it off and leave my FIAV working so that i would still get the fast idle at start up.

My first attempt was to block only the passage that the ISC air goes through. I used some aluminun plate that I RTV'ed in place. The passages in there are pretty convoluted and i must have not blocked all the passages, because it didn't work.

So i just sucked it up and blocked off the whole thing, I sealed off the passage that leads to both the ISC and the FIAV. That was pretty easy and it worked. Now I don't have my ISC problems and the only drawback is that i have to warm up the car with my foot on the gas.

 

[Turbo442]

I use to think my throttle body and intake manifold were getting hot from the coolant lines that run through the throttle body. After my FMIC install I realized it was the hot air from the turbo! My TB and intake manifold are warm to the touch instead of screaming hot with the side mount...even after an hour of driving.

 

[anconover]

i took mine out because its one less coolant hose that can pop off. I have no wierd idle, car starts/idles fine when its cold.

 

[beat90tsi]

Turbo442, everyone knows that the coolant lines have a minimal effect on the temperature of the TB. Please stay on topic.

ancouver, could you elaborate on your fiav removal on your 90?

 

[Dtab123]

i had idle jump for 1000 to 2000 rpm's and someone told me to remove my fiav and it fixed it was there another way to do it???

 

[zrk666]

i would really like to know what holes to block off so i dont screw anything up. the TB is in my gallery.

thanks for the help.

http://www.dsmtuners.com/gallery/showphoto.php?photo=53385&password=0&sort=2&cat=500&page=1

 

[DSM90AWD]

Having had one of my FAIV lines rupture during a 1/4mile run was interested in eliminating this "feature". This is what my 1990 TB looks like with the lower cover removed. Note (as mentioned above) is not the same design as the 91-94 two-piece unit.

<img src="http://www.dsmtuners.com/gallery/files/1/0/3/6/9/1990tby.jpg" alt="1990 Throttle Body" />

The FAIV allows air to pass from #2 to #3 boosting Idle RPMs for cold startups. When the coolant reaches a certain temperature the FAIV moves (much like a thermostat) and gradually blocks this passage bringing Idle RPMs back to normal.

My thoughts are that blocking off #3 hole (the FIAV outlet) should do the trick.

I also agree that the FAIV elimination would have little or no affect on performance as the coolants exposure to the TB itself is minimal. The only consideration for this mod should be the elimination of possible boost/coolant leaks and easier removal of the TB

 

[BISHILVR]

"The FAIV acts much the same as a choke in that at startup is restricting (e.g. "choking") air to the engine which boosts idle RPMs for cold startups" Actually, it's quite the opposite, the fiav provides MORE air at cold idle to allow the rpm to rise, and closes as the coolant temp comes up. Its known as a bypass air system.

 

[DSM90AWD]

You're 100% correct. I was high on carb cleaner when I wrote that
edited post