RotorJoe

I started a thread in the general tech section, but this maybe a better place.

Just last night I notice that if I roll on 5th going up a slight incline at full boost (1.1 bar or so) the boost will fluctuate or oscillate by about .1 all the way to red line. While it is doing this the car will surge too. Not a great deal but just enough. I don’t notice it in any other gear but forth on hard up hill pulls. All the other times, the car moves through the gears so quick that I don’t notice it. Plus it does not happen at .8 of a bar. I could be wrong but my butt dyno states that I am a touch low on HP.

To me it sounds like I may have a slight and hard to locate boost leak. Any suggestions on how to track down a small and only apparent boost leak at high boost? But I could be wrong and my stage two twins could be going out? This does not happen if I down shift and redline the car that way. I think the car just moves too quick through the gears that way to see the surge/fluctuation/oscillation of the boost.

I will be changing the brakes pads and looking into this issue tonight and suggestions would be helpful. I have also tried searching with not much help. Maybe my keywords could be better or the fact that I only read the title could be why I missed it. So…if any one is a master searcher that can help that would be appreciated.

I guess I am leaning and hoping for a slight boost leak that only appears under full load and full boost.

P.S. I am non seq with a hks evc controlling boost. Never had issues yet. The rest is in my sig.

Thanks a Bunch
Joe

edit: well I couldn't redline 5th, ran out of road. Darn. But 4th yes and the problem occured but much less. I also moved through the RPM range of that gear quicker then 5th so that may have something to do with it. Thanks Again.

adam c

iTrader: (2)

You don't have a boost leak if you can sustain full boost in other gears. It doesn't go thru third so fast that you won't notice a drop.

RotorJoe

I just ran into this issue last night. I am leaving work right now and I will play with it some more. Hopefully I have more info tomorrow.

I can always use an extra set of eyes/brain/experiences.

Thanks

RotorJoe

You are right it happens in third to if I pull from 3000 all the way to red line. Fourth the same and fifth even more.

I spent some time under and over the car. No exhaust leak and I am almost sure (along with you) that I have no boost leak (this weekend I will fully pressure test the intake and intercooler to verify this).

Spent much time searching more and found I could be having problems controlling the waste gate which opens up a whole realm of issues that it could be. I will be playing with my boost controller (sending it back through the boost response learn mode) and just for ***** and giggles play with my duty cycles in the PFC (I know this should not affect it due to my stand along boost controller, but it’s a thought). I also have an AVC-R hooked up that I have never played with and not sure why it is in the car. If I disconnect it sends the boost sensor for a loop and hangs at 4.5 volts. Can we say flooded? So I need to see if the AVC-R could be a problem too. I will also be reading up on the boost pills and looking as to how my car is set up (don't you just love jumping into a half finished project and trying to figure out what the hell).

Wow lots to look at and ideas/thoughts anything is helpful.

jimlab

At what rpm does it start to break up? Many FDs have misfiring problems above ~6k after the boost level is raised significantly, and most people add ignition amplifiers to solve the problem. Since you already have an HKS Twin Power ignition amplifier, it's possible that there's something wrong with it. The fact that you say it doesn't happen at lower boost levels tends to support the high rpm/boost misfire theory.

If you feel like you're losing power, it's probably misfiring, or worse, you're experiencing light detonation which is causing the hesitation or surging, especially in 4th and 5th where load is highest. Regardless, I'd knock off the 4th and 5th gear pulls until you find out what's wrong with your car.