Nammy

iTrader: (6)

A couple weeks ago I installed the HKS Legamax Premium exhaust and center pipe as well as an AccessPORT using the Stage 1 93 map. The car is otherwise stock. When I took it for a drive, I immediately noticed a rushing air noise that seems to be coming from the engine bay when the car is under heavy load. The next day, it still was not making power like it should be (it felt weaker than stock, and I figured the ECU would be done learning by now). I drove it normally for a few days, and then one afternoon on my way home from work I took it WOT briefly and even though I still had that noise, the car felt like it was making a good deal more power than when it was stock. That night, I upgraded my AccessPORT to the latest firmware version, and reflashed the car to take advantage of the new features. I drove the car normally for a day, but then my power never came back. A few days later I decided to uninstall the AccessPORT entirely to see if that was the issue. A few days later I still had the noise and it still felt weaker than stock. I then got back under that car looking for soot lines that would indicate an exhaust leak, but did not notice any. I checked all of the hoses under the hood and everything seems to be in order. I reinstalled the AccessPORT with the Stage 1 93 map so that I could do some data logging. I did a few pulls to redline in 4th and 5th gear, and I noticed that the ECU was seeing some knock, which was retarding the timing down into the single digits. I'm assuming that this is the reason the car feels under powered, and I'm also told that this is probably the cause of the noise that I am hearing. Thinking that I might have gotten some bad gas right around the time I installed the mods, I ran the tank as low as I could get it, filled up at a different station, and put in a bottle of octane booster. Now, with that tank of gas nearly gone, I am still having the same problems.

I'm wondering if anyone here has any other ideas? Could the exhaust be causing this issue? I was hoping I wouldn't have to put it back to stock and take it into the dealer.

Clark_Kent

iTrader: (5)

Did you contact Cobb? That might be a good start.

Nammy

iTrader: (6)

Well, no. I figured the AccessPORT was not the issue since the problem remained two days after I had uninstalled it. I'm just using it as a logging tool at this point.

Spazpilot

iTrader: (4)

Air noise could just be a boost leak somewere and it just happened as you installed the AP and exhaust. None of the two would cause an air noise. I would start by checking your clamps on the IC pipes and vacum lines

LVSBB6

iTrader: (4)

Even with the car is bone stock, the Cobb AP will record knock retard even with stock base map. i was told if the numbers are within 1 or 2 in partial throttle its considered normal.

Nammy

iTrader: (6)

I did glance at the hoses and everything seems to be good. Furthermore, looking at my AP logs, it is peaking at around 23 pounds of boost and holding right around there until I let off the throttle. This leads me to believe there is not a boost leak. Unless it is possible to have a leak minor enough where the system will still pressurize properly, but at the same time you can hear it when it is pressurized?

Nammy

iTrader: (6)

Mine is showing 0.35's and 0.7's at full throttle. It is still making the timing retard though, which is causing my power to drop. At least, that's what I'm seeing in the logs.

LVSBB6

iTrader: (4)

i also get the same numbers as you occasionally at WOT, if they are under 1 you`re fine. We couldn`t detect any knocking with these figures even on the dyno.

Nammy

iTrader: (6)

Does your timing drop into the single digits as well? If so, is that considered normal also? On mine, for example, it will be building power fine, then it will see a knock, and then the timing retards and it drops 50hp. The car feels like it falls flat on it's face when that happens. It also still does not pull as hard at lower speeds as it did when it was stock. Maybe I'm just crazy, I don't know. This still doesn't explain the noise I'm hearing. Back to the drawing board on that I guess.

toshibakoludo

Take it to the dealer and let them check out the car. (With stock tune) they might spot something you missed. Then flash it once it's all in optimal working condition. Just wondering did you re-set the ecu after catback install?

skatermsmn

iTrader: (7)

I wouldnt take it to a dealer, just take it up to a local performance shop and let them log it a bit. But before that, do a boost leak test just to be sure.

goofygrin

iTrader: (5)

hearing a whoosh without an aftermarket intake, to me, means that something under the hood isn't working right.

SiC

iTrader: (1)

You say that the ign timing goes into single digits but that is pretty normal at low RPM WOT. Now if you are talking about mid to high RPM, that may be caused by knock. Does the ign timing suddenly drop in the middle of a WOT pull? Or does it drop as soon as you go WOT and gradually rise?< If that's the case, it's pretty normal.

Mad_SB

iTrader: (8)

What is the sample rate on the AP logs?

I looked at another AP uers logs to see if I could help him diagnose some hesitation.... The sample rate was way too low (like one row per 500 rpm). The X seems to reacts much faster to sensed knock than the VIII's and IX's. It can pull out 2 degrees and give it right back in the space of 100 to 200 rpm during a pull so don't just go by the logs. With 500 rpm between samples you could have two different knock events and never see them at all.

Follow SiC's logic above and see if you can improve the sample rate on the AP by cutting down on the logged parameters.

Nammy

iTrader: (6)

The timing looks to be retarding across the entire RPM range, which makes sense to me because the car does not feel like it pulls down low like it should, and then it feels like it falls on its face at speed. Almost as though there is a point where the car just simply stops accelerating, and that point isn't the speed limiter . I'm driving the car to Atlanta this weekend to look it over with a friend. Thank you all for the suggestions, and I'll let you know what I discover this weekend - if anything.