[Supraman16]

Hi Guys,

Well, I got to thinking about the stock dual stage intake and figuring out a way to keep fender side intake opening open all the time. In case you didn't know, the fender side intake opening is closed until around 3600rpm, which is when it opens up, thus resulting in the now infamous and much beloved "IS-F Roar". As you can see from the picture below, all I did was just pull off the vacuum hose from the actuator and plug off the other end with a vacuum cap. Now the "IS-F Roar" comes on around the 2300rpm, and to me atleast, there seems to be a bit more power down low...which makes since because now the engine can breathe a bit better down low with both intake opening being open all the time. The only downside would be if this throws off the air/fuel ratio's from stock. I don't think it will drastically, but I'm not sure. Anyway, try it out and let me know what you guys think. Oh yeah, no check engine light either! Have fun...Darshana S...

 

[Supraman16]

I would highly advise against this modification. The problem with the IS-F is not down low (where I have reached sixty in 4.2 seconds numerous times) and where there is an abundance of power on tap early but rather after 5,000 rpm's where we have seen torque curves drop off significantly, and where both intakes are fully open. Voiding your warranty to hear the often talked about "whoop" 1,000 rpm's sooner is simply idiotic, and something I would expect from Chevy iroc or Ford mustang owners!

IROC- Itailian Retards Out Cruising

I didn't do this so I can hear the "whoop" 1000 rpm sooner. When I was driving around my IS-F in non-sport mode, it felt so much more sluggish than being in sport mode. It literally felt like it was still trying to breath and there was something in the way. Well, that feeling is definately gone now. It's significatly much smoother now down low in non-sport mode with this mod. I drove around both in the street and the highway yesterday and I also had a friend drive the car, both with this mod and without this mod, without telling him what I did, and he also felt the same difference...that it's much smoother down low. Your right, the main problem is after 5000rpm when the torque drops off significantly. I believe that at this point the stock intake is very restrictive and the car just can't get enough air...you need a aftermarket intake to fully solve this. In regards to voiding the warrentee...this mod can be so easily reversed that no one will know that it was even done! ...Darshana S...

 

[Supraman16]

of the vaccum to OPEN the fender vent above 3500 RPMs? If the vaccums disconnected, how will the fender vent open and stay open all by it's self? Wouldn't it just remain closed all the time, in it's normal resting state?

The resting state is the fender intake flap in open position. You can check this yourself by just taking off the passenger side engine cover and you can easily see the intake flap. If you have the vacuum line connected, as soon as you start the engine the flap closes. Disconnecting the vacuum line, like I did, results in the flap being permenantly open...Darshana S...

 

[Supraman16]

having performed the described mod last night. The air temp this morning was about 65 with about 20% humidity. I ran the car both through the twisty's in the hills where I live and then up on the freeway and back home again.

I have to say I really like the result. The car perfoms much better in both the auto and manual modes, without using the Sport setting. Yes there is more power and low end torque, but more importantly for me is that there is a faster throttle response thoughout the RPM band. Just like most things, allow it to breathe easier and it will perform better.

If there was a drop-in high flow after market air filter out there we'd all jump to buy it IMHO. Isn't this really the same thing but for free? I will keep an eye on my air fliter and will expect to have to change it out sooner then reccommended with this mod. Not sure there is any possible downside to this mod? Would enjoy hearing others experience with this!

The much improved throttle response was also the thing that I felt the most. I'm glad you like the mod. Hopefully others will try it and give feedback...Darshana S...

 

[Supraman16]

Hey, about the drop in performance air filter, I made some measures calculations and I believe found one . Will post update soon as it gets here and test fitted. By the way there's no company making one for the F.

Definately keep up updated!...Darshana S...

 

[Supraman16]

Well guys finally is here I tested for a few miles around my house last night. I did not feel that much of a power but it sounds awesome, maybe the ecu needs time to know the new mod(more air). Later today will double check the airbox for proper fitment.

What was the filter you got?

 

[Supraman16]

In other news, the vac plug is not necssary at all. You can simply unplug the solenoid. Since it is not a critical system, there is no current sense on it. Works great

After looking at the intake system it is my conclusion that the factory macroni pipe is not restrictive at all. Even the damping mechanism is very minimal. I think I did figure out what can be improved...and that is the airbox/ram air. I will keep you gys posted and start a thread once I get further along. Feels good to get into the engine bay again and tinker

Fig

Fig,
I thought about doing that initally also, but I wasn't sure if it would trigger a check engine light so I decided to "fool" the system into thinking that nothing was disconnected. But I don't know too much the stock ECU (I don't think anyone does) to know whether that stock airbox plug does more than just control the secondarly intake flap...hopefully it doesn't also have some part to play in the air fuel ratios?? I doubt it, but I was just playing it safe by doing the vacuum cap mod rather than disconnecting the connector. But anyway, do you notice a difference in the throttle response also?...Darshana S...

 

[Supraman16]

Hi Guys,
I'm glad you like this mod. I've had it done now since I originally posted up this thread and I have yet to find a negative effect from it. Gas milage is the same, the sound is incredible...even more so in combination with the JoeZ exhaust I recently got, and more importantly, a bit more noticible power in the low end. However, the only thing I have found out and want to advise everyone one against is getting a drop in air filter, like a K&N filter...DON'T DO IT...with or without this mod! I had the K&N filter and it felt like it was making more power initially, but then it went away...likely when then ECU adjusted to it and the MAF got contaminated with the air filter oil. I started having really poor gas mileage and this promted me to put back the stock filter (along with the fact there was a thread on CL about how the K&N filter as causing problems to other members IS-F's). But yeah, I've had this mod for awhile and still nothing bad that I have experienced...Darshana S...
PS. I have mine done the original way...with the vacuum cap rather than disconnecting the solinoid. I didn't want any water or debris getting into the open connectors.

 

[Supraman16]

I've had my K&N now for 2K miles. I also have the JoeZ intake tube. So far no issues with my K&N.

BTW, I've used K&N for years. My last car, a G35 coupe had a MAF, and worked fine for 6 years with a K&N. It was cleaned and reoiled countless times.

Lou

Hi Lou,
May I ask what your gas milage is? The reason I asked is because poor gas milage was how I found out that the K&N Filter was not a good idea. With the K&N Filter I was consistantly getting no where better than 16mpg. After cleaning the MAF and reinstalling the stock filter I started getting 19-21mpg. I didn't actually notice or feel any oil on my MAF when I removed the K&N filter, but obviously, my IS-F was not happy with the K&N filter. I still got a K&N cone filter on my Supra TT and it has served me well for years, so I'm going to stick with it in the Supra, just not with the IS-F....Darshana S...

 

[Supraman16]

Hello Superman16 this is BJG403 I have a 09 isf i tried it also .I do think there is a little more power on the low end.Did you cap off the other end.

Hello,
Yeah, I capped off the other end so no junk goes in the actuator. Glad you like the mod...Darshana S..

 

[Supraman16]

Are there any problems so far with this mod? There must be a reason why the car has this part to begin with. If we take it off, what purpose are we defeating?

I've had it for several months now and still no issues whatsoever. I believe that the reason that Lexus did this was due to keeping the car quiet in the lower RPM's. I don't think that there is any performance reason from keeping the secondary intake closed in the lower RPM's...Darshana S...

 

[Supraman16]

i took mine off over the weekend and you can really hear the difference in the exhaust. hard for me to believe the car can me slower with this mod. anytime an engine gets more intake air it will produce more power.

one we remove the hose, should we cap of both sides of the solenoid?

You should cap both ends of the solonid to prevent any gunk from getting into it.

In regards to Juanca's data...I feel there is one major flaw in regards to the track conditions. The day that he did these runs were approximately 20 degrees cooler...thus worse for grip. Now you do this mod with I still believe results in more torque and power down low (this is what I feel, I don't have a dyno to prove it), you have a bit more wheel spin and thus lower ETA's and MPH, especially on the 1/8th mile. The 1/4 mile would be more accurate for both ETA and MPH and using the MPH for estimating the HP. With the flap closed/in stock mode, you have less torque and power down low and therefore less wheel spin (especially on a cooler day) and thus better times.

I have had this mod since I first came up with it and I have reversed it several times to see if it was only a part of my imagination that my car felt stronger down low with this mod. Sure enough, every time I chaged it back to stock it felt like my car was suffocated down low (kind of makes sense...it's not allowed to breathe as well with the flap closed). The throttle response was definately not as crisp with the flap closed/stock mode.

I currently have the JoeZ exhaust (which by the way is INCREDIBLE) and it seems that this mod makes even more power because now you have the car less restricted in the exhaust side and when you let it breath easier on the other end (intake side), you have a better performing car.

Juanca has some great objective data, but it is not completely equal given the track temps. I however like how my car feels with this mod and it's easy enough to return back to stock. I encourage people to give it a shot and also consider what Juanca has posted and make the decision for themselves.

Have fun modding...Darshana S...

 

[Supraman16]

I tried it for a day and somehow the car idled at 500 rpms as opposed to its usual 8 or 900... dunno y that was the case, i plugged it back in and the car went back to normal... does this happen with all of u?

Sounds like you have a vacuum leak when you unplugged the solinoid. Make sure the vacuum cap that you used isn't cracked or has a leak...I personally have had rubber vacuum caps that have a very slight crack in them that you can't see without looking at them very carefully...Darshana S...

 

[Supraman16]

Hey,
I'm new to this forum and could use some help

I'm owner of the MY09 Starfire Pearl ISF. Today I tried the DIY intake mod but I chose the easier option, and just unplugged the connector leading to the small metal box as per the photo instructions of the other member, instead of fiddling with vaccum hoses and caps.

After unplugging the connector, I started the engine and let it warm up by driving slowly around town. To my surprise, there was absolutely no change in the sound, and the "ISF roar" came at regular 3600rpm. Dynamic characteristics of the car also remained subjectivelly unchanged.

After parking the car in the supermarket lot and starting it up 10 minutes later, I got the engine light come up together with VDC Check. These fault indicators remain lit even after plugging of the connector back and driving around for about half an hour. Car still runs flawlessly though.

So my questions:
1. How do I get rid of the engine fault and VDC check indicators?
2. Why didn't the mod work for me? Did I unplug wrong connector (there seems to be just one)? Wasn't "the roar" supposed to arrive sooner, at around 2000rpm?

This is odd. I've been running this mod for now 2+ years without a problem. I've also coverted over to the "disconnecting the plug" method rather than the vacuum cap method because I've noticed after awhile the caps would start to crack and leak. Anyway, in regards to your problem...I would reset your ECU and try to get rid of the problem codes, or better yet, get a OBDII scanner and pull the trouble codes before you reset the ECU. Do you have any other mods on your car such as a Throttle Controller, etc?...Darshana S...