I recently installed Berk hfcs and the spec d exhaust. Yesi t sounds atrocious which is why im installing 2 18in resonators. But my question is why is my car so low powered now? Is it really running lean because of the lower backpressure? I will add that the passenger side berk hfc had a small weld missed on the o2 stalk. Yes i am going to have it welded soon. But i noticed it before installing but needed to get my cats off, they were falling apart badly. My cars got 128k and only other mod is a mishimoto oil catch can. The reason im confused to the power reduction is that the cars engine light never came on, nor is it throwing any codes. I thought it would be running like garbage because of the incorrect o2 readings. Just wondering if anyone else had the spec d and berks and noticed a huge power reduction. If everythings reading correctly, do i need to be retuned?

 

Reducing backpressure will not cause an engine to run lean, backpressure is sort of a myth also, you don't want backpressure.

Were these parts brand new?

 

Im pretty sure backpressure is directly and proportionally related to the distribution of exiting density of emissions being dispersed through a larger diameter tube. But yes, everything was brand new when installed. However ive seen people run similar setups with the same hfcs, different catbacks, and they run fine. I just dont understand how theres such a substantial power loss along with there being no cel nor codes. And all of this started right after installation. The reason for my backup of this via anecdotal findings is previous cars ive owned have lost low end power and gained mid to high on the power band, and ive been told for the vq i would lose low end for sure. But im talking like 50-60 hp difference currently

 

Let me dig up a post I made a while back that explains it in more detail.

As for the power loss I would start by checking to make sure you have the correct cam advance, pull plugs, clean air filter, general maintenance type stuff.

Are you SURE there are no codes? You hooked up a scanner yes? The CEL doesn't always illuminate but the ECM will still store codes.

Things like the knock sensor sub harness failure (throwing a hidden knock sensor code that doesn't illuminate the CEL) will prevent the ECM from actuating the intake cam solenoids which pulls about 30 degrees of cam timing and about 50 whp.

Also, the HFC's WERE BRAND NEW yes? Also, you thoroughly inspected the tubing of the exhaust system to make sure no packaging material or anything was stuffed into it yes? You could always pull the exhaust y-pipe off, hang the midpipe, and go for a drive to see if it picks up power which would indicate some kind of exhaust restriction.

 

Check this post out for a brief overview on exhaust stuff.

https://g35driver.com/forums/intake-...ml#post7217330

 

ok man ill check that out, and yes i checked codes as i know the cel comes on for some codes and not others. And pipes were good, free of packaging stuff inside

 

Ok and the reason I keep asking if the HFC's were brand new is it's possible if they were a used set that someone screwed them up from running rich and sold them anyways. Typically you will see melted spots on the element inside if you look with an inspection mirror and flashlight, or borescope, but sometimes they melt in the middle and you cannot see it.

 

I remember going oem cats > ART pipes > and back … very noticeable immediate power gain … and then loss. berk hfc are famous for cooking and blocking the exhaust.

I agree with Cleric.

 

I still have never tried a set of ART pipes, some day when I find them on the cheap I'll throw a set on.