There is a huge issue with the HKS suction intake pipe in that it will throw off the MAF readings at idle. It will make the MAF read about 50+ Hz when it should be reading around 38Hz. The higher Hz value won't let the STFT low to self adjust because the MAF is out of "low range." Below is information on how I got it the HKS suction intake pipe to idle at 38Hz.....

1) Purchase a 3" to 2.5" 45 degree silicon coupler
2) Install the large end of the 45 degree coupler onto the MAF on the Intake pipe side (it will be very tight so some lube is necessary) (no clamp yet)
3) Install the HKS 4" to 3" reducer over the other coupler so that the HKS reducer would mount on the MAF as it usually would (it will be tight so som lube is necessary)
4) Install the small end of the 45 degree coupler that is now attached to the MAF into the large end of the HKS scution pipe and allow the HKS reducer to mount onto the HKS suction pipe as it always would.
5) You will have to rotate the 45 degree coupler and/or the MAF to allow the MAF to mount correctly. It takes a little work but it will line up the MAF top and the recirc tube both facing up and parallel
6) Install the smaller clamp onto the HKS reducer to hold the sandwiched 45 degree couppler in place on the MAF
7) Instal the Large clamp onto the HKS reducer to mount the MAF to the HKS pipe
8) Install the assembly into your car

Once the 45 degree coupler is installed you can look inside the small end of the HKS suction pipe you will be able to see that once it is installed correctly there will be a small gap where the vacuum tube inlet goes. This will still allow necessary vacuum to the valve cover.

What essentially is happening is that we are re-establishing the same effect the stock rubber tube has on the MAF. At the same time we are allowing the smoother flow of the HKS pipe to remain in effect for higher throttle.

I varified that MAF Hz does in fact idle at about 38Hz with the 45 degree coupler installed.

This is still UNTESTED for WOT runs. I will post up results later in the day.

 

People are looking well here are the results......IT WORKS GREAT ! !

My fuel trims never looked so good. The car is still learning the LTFT low but it is sitting at +4.6875 and my Mid......+0.3906.....PERFECT.

MAF scaling is coming along nicely. I had to increase the Unit in every value below 175 Hz. The car runs great. My MPG is improved too. A little more tweeking of the MAF and I will be golden.

Oh and WOT....just like it was before the coupler was installed. Absolutly no loss in power according to EvoScan.

 

You need to post pics of the install... cause I am hella confused on exactly how you are doing this...

 

Yeah I am lost in your description as well.. This is something that is best illustrated.

 

OK I have a new filter on the way. When it gets here I will update the thread with pictures.

In easy terms though....put a 45 degree coupler on the MAF, insert it into your HKS pipe and clamp it as you normally would.

The HKS pipe is 4.5 inches on the inlet side. There is a 4.5 to 3 inch reducer that comes with the HKS pipe to allow the pipe to connect to the MAF. on an untuned car the pressure drop created by the HKS pipe causes idle issues with bigger cams and larger turbos.

The coupler is the same size as the MAF so there isn't a pressure drop any more. The reason to have to use a 45 versues a straight one is becasue the HKS pipe bends quickly. The 45 will follow the bend.

If you look at the Perrin, buschur, and ralliart pipes; they all are about the same size as the MAF and therefore don't screw with the MAF Hz reading like the HKS pipe does. By putting on the coulper we are essentially mimicking these pipes.

Oh and for the record....with a bit more MAF scaling I now have my LTFT low at +2.7343 and ltft Mid at +0.7825. The car idles geat. Never stalls.

If any of you wat to give it a try I will post my MAF scaling to get you in the ball park.

I know it seems comfusing, but as soo as you put the 45 on the MAF you will see exactly what I am talking about.

 

Oh man! I think you just gave the reason for my issue on a post I made. I have the same problem. Now I have to figure out how to do this on a 35R. Lol

 

Just to confirm, I took out the coupler and my MAF Hz at idle jumped back up to around 55Hz. And, the LTFT Low won't adjust any more.

I am going to try and calibrate the HKS suction pipe without the coupler.

The reason I took it out is to see if I can gain some more top end power by removing the restriction.

I will report back with the results.

 

After messing around with the MAF scaling, MAF smoothing and Idle stuff, I could not for the live of me get the HKS pipe to idle without stalling if the idle Hz isn't below 40Hz.

I reinstalled the 3" coupler onto the MAF output side, inserted it back into the HKS pipe....and again everything is perfect. Trims are great, idle is smooth, and no loss in power.

 

out of curiosity, what turbo and cams are you running?

 

FP Green, Revolver Cams