Lag Is Killing Me!

[bambis]

Hey all,

My BA 4 Spd Turbo has a slight problem. Each time I think ive got it, it comes back >< Driving along at any speed, in any temperature and plant it. The auto drops into 2nd and boost builds. Now it gets weird, as boost builds higher the engine revs seem to remain the same, or climb slowly. This occurs usually at mid range, say 3-4k, all I can hear is the turbo whine and it all sounds fine but there is no power, no acceleration. At this point I look at my mechanical boost gauge which says 20-22psi... Car is tuned for 15psi, and holds this pressure very well normally. If I just plant it from stop it will accelerate normally like there is no issue. If I am cruising along at 60kms and use tiptronic to change to 2nd and then WOT I get the issue.. This is an intermittant problem, it might not do it tomorrow. Car has done this since I first had it tuned. When I had the actuator replaced I had it retuned, and for a while it was fine and now its back again. Now this sounds an awful lot like the car is overboosting.. (do I have an highflow cat I dont know about?)

Question is, if the ECU senses overboost will it limit fuel or retard spark like the traction control?

If overboost is the culbrit what fixes it? Tune or controller?

Im trying to understand what may be causing it. I cannot afford to pay $500 to have it diagnosed then pay $30 for something ive missed..

Here is a list of things ive done to the car to help maintenance and below in my sig you can see my mods.

New Plugs (Genuine, gapped at CV)

New Coils (Cheap knockoffs, although there might not have been anything wrong with the genuine ones I had for 6 months)

Walbro 341 (This was the first thing I changed thinking the stock pump was the issue)

Fuel Filter

Actuator

Any advice would be appreciated!

thanks all.

Edited 14/10/09 06:33 AM by bambis

[Buf-Phoon]

Have you spoken to the boys at CV , had it checked for error codes ?

[bambis]

Hey buff,

made a quick call this afternoon asking about overboost and they said that they may just need to touchup the tune. but as ive said, im not prepared to pay $500 for a retune. Although if it is a tune issue they probably wouldnt charge me anything to correct it.

[Buf-Phoon]

If it's tune related I'm certain it won't be a problem. They have tuned loads and loads of these things and have a far better idea and better equipment than most of us to diagnose the problem.

Did you mention this gremlin after the first tune?Not sure if its the tune as boost spikes stick out like dogs balls. Does your dyno sheet show a flat boost curve. But as you say it's intermitent. You really need to talk to Con.

[bambis]

Did you mention this gremlin after the first tune?Not sure if its the tune as boost spikes stick out like dogs balls.

The problem arose a few weeks after I had it tuned to 270rwkw. That was the 1st tune the car had. After doing all the obvious things I listed I decided to replace the actuator and retune. I briefly explained the issue when the car was retuned and when I got it back it was gone. That was like 3-4 weeks ago. As strange as it seems, it started doing it again a couple days back.

Ive also been thinking that I may have an exhaust leak, sounds a little like it. But im assuming that there is no way that could influence anything.

[Buf-Phoon]

here's a real roughy, reflash your tune and see what happens

[bambis]

lol I never thought of that... I might have to try that, but then im not sure what might happen when I use a 10 or 8psi tune with the 12psi actuator, and would the CV tune even be stored on the box? or must it be stored in order for it to be transferred to the car?

might need to try this and see what happens..

[Buf-Phoon]

you have 3 tune slots ( I'm assuming a Capa 1 box) plus the factory slot.

The CV tune/s will be stored in the box. Which slot is your big gun tune with the actuator upgrade ?

I am guessing number one. Again CV will have the files to confirm this

[Ozzy]

I briefly explained the issue when the car was retuned and when I got it back it was gone. That was like 3-4 weeks ago. As strange as it seems, it started doing it again a couple days back.

Sounds like they may know what the fault is ... but dont want to say.

However ...

here's a real roughy, reflash your tune and see what happens

Im a fan of this.

There is a chance that all they did is reflash the ECU and than was enough to patch the fault. Try it and see how long until the fault returns. If it returns that is.

Question about the fault Bambis.

You said in the first post that the fault occurs when a kick down at WOT is requested, but its ok if you just drive off from the lights normally. Have you done anything to the transmission? Cooler(s), checked oil level, oil condition or serviced it of late? Sounds like what my mates blown BA XR8 (auto) did not long before the clutches failed ... and 2nd gear was first to go.

Im not going to say that's the fault, just saying what Ive seen. Im all ears when you find out what the fault is!

[bambis]

Ozzy,

I really hope the clutch isnt going. But this afternoon I went for a drive to test it a bit. If I accelerated with WOT there was no issue. But if I was in 2nd gear using tiptronic doing any speed and went to WOT then it would happen. 1st isnt an issue.

Ill try the reflash tmoz and update ><

thanks guys