Bluefin Stage 2 too much boost .. not enough fuel pressure?

[Mark_GTIV]

Hi there,

Now I've got VCDS I decided to do a bit of logging - I've been experiencing a couple of flat spots in the delivery of power from my stage 2 bluefin mapped car.

Well.. I've noticed what the problem is : the car is boosting slightly over the specified boost up to 1.4 BAR achieved and this is causing fuel delivery issues, where the fuel rail pressure achieved isn't matching up with the requested on wide open throttle, with the engine heavily loaded in 5th/6th gear pulling through 3000 to 4500 rpm.

Here is a graph



I think I need to contact superchips to see what they can do first thing Monday.

Anyone had this with bluefin stage 2?

I've got a Milltek hiflow downpipe, Milltek hiflow cat, milltek exhaust, Forge DV and Carbonio CAI with ITG panel filter.

[Greeners]

At the last RR day I went to mine was losing boost high up (over 6k) and I'd noticed it for the first time on the way there that very day!

Going to get SC to look at it whilst at the RR day next week! 

[gadge]

From what i know over on the VXR's. Bluefin/SC tend to run higher boost levels.

[Mark_GTIV]

The ECU is usually requesting 0.1 to 0.2 bar less than the car actually achieves. When the car is achieving 1.43 BAR boost, its seems its too much for the fuel rail because you can see the pressure drop away by 10 to 20 bar from the requested fuel pressure when the car hits that boost. Slightly lower boost and its fine.

You can see it clearly from the graph. The top two lines are Boost Requested and Boost Achieved - i've scaled them if you add a 0 to the end of the number you get millibars and then deduct atmospheric pressure of 1080 millibars and you get boost pressure

The next two lines down are the fuel pressure requested on the rail (in blue) and the fuel pressure achieved (in red) - they are measured in bar.

The horizontal axis is RPM.

And the bottom green line is the differential between the requested and the achieved for the rail pressure - also measured in bar. When you see the differential line spike - there is the problem - both times at peak load in the 3000 to 4500 rpm peak torque zone where the car is running 1.43 BAR boost.

[vwrascal]

^^ Wow, sounds like you know your stuff! quick Q? How do you log that data? I have vcds hex-can, do I need to go into 'applications' and then 'transport mode'??     sorry for going off topic   

[Hedge]

^^ Wow, sounds like you know your stuff! quick Q? How do you log that data? I have vcds hex-can, do I need to go into 'applications' and then 'transport mode'??     sorry for going off topic   

Please don't. All can be found on the Ross Tech website. http://www.ross-tech.com/vcds/tour/m-blocks.html
Select 01 Engine and 08 Meas Blocks or Adv Meas Blocks http://www.ross-tech.com/vcds/tour/adv-meas-blocks.html

[Mark_GTIV]

^^ Wow, sounds like you know your stuff! quick Q? How do you log that data? I have vcds hex-can, do I need to go into 'applications' and then 'transport mode'??     sorry for going off topic   

Dont know about knowing my stuff.. it's a learning curve.

Logging the data is quite easy - For this sort of stuff go to '01 Engine' then 'Measuring blocks' - choose the groups you're interested in. Then click log to file. it creates a .CSV file under the \logs directory of the place where you installed VCDS on your PC and you can just open it in excel and analyse it.

[vwrascal]

just been out for a drive with vc graph running and I am impressed  the graph is moving up and down like a donkeys hind leg, felt like a fast and furious moment with the laptop incar whilst driving  havent a clue what anything means but at least I looked COOL   

[vRStu]

I can't really read your graph very well, for me it's easier to look at the numbers.

You will get a drop in fuel pressure at the mid range, it's a known limitation of the stock fuel pump. 

I think your graph may be making it look worse than it is.

[john_o]

crikey , everyones logging rail pressure these days lol
A drop in rail pressure to some degree can be normal. esp as you are seeing no more than 20 bar differential. I wouldnt bee convinced its that ,thats giving you an issue. Any fault codes / misfires etc?? or is it just 'flat' feeling?
What are youre timing / EGT / N75 etc ?

[Mark_GTIV]

Hi there,

During this phase of fuel pressure drop in the high torque zone, timing goes down to a steady +3, fuel pressure is fluctuating all over the place, but on average a 20BAR less than requested.

The car goes from feeling strong with a nice consistent surge to a slight feeling of alternating gentle reining in during the 3750 rpm through 4300 rpm, then it comes strong again and then the same feeling as it passes peak power in the 5300-5500 rpm range. - I only feel this if I'm doing a wide open throttle pull in 6th gear starting at 2000 rpm.

Last week, it threw a DTC code P0087 Lower limit fuel pressure intermittent in the Engine ECU at 3200 RPM with WOT in 6th gear and the car did an enforced throttle reduction.

So, I think, perhaps because of the Forge unit (I'm running the stronger spring), in my particular case, the bluefin programming will need it's requested boost toned down by 0.1 or 0.2 BAR to stop it 'over boosting' and maintain fuel pressure in this danger zone. I suppose they programmed stage 2 for a normal diaphragm valve with the only hardware change expected being a hi-flow cat and down-pipe.

I'm going to have a conversation with SC on Monday.

[haithame]

i have the same problem and i have P0087 - 002 - Lower Limit Exceeded - Intermittent
i contacted Superships many times trying to solve that...they tried to send me several files trying to reduce the boost BUT NOTHING WORKS....by the way i am using the factory dump valve

[Mark_GTIV]

Yeah I read your story with your conversation with the guy from australia on mkvgolf.

 I think my problem is a little different from yours, because when I read your story, your fuel pressure requested versus achieved was inconsistantly variable all the time, whereas mine is only inconsistantly variable on high load, in a specific series of RPM where boost is excessive (i.e. 1.43 BAR).

At anything lower than 1.4 BAR boost, my fuel pressure is perfect. I'm going to ask SC to scale back the requested boost in the danger zone, so that the car will only achieve less than 1.4 BAR boost in those areas and then I think it will be fine - I'll let you know how I get on.

[vRStu]

I think you are showing classic signs of fuel cut.  Upgrading the fuel pump internals would solve the problem or going back to Stage 1 software. 

[Mark_GTIV]

I think you are showing classic signs of fuel cut.  Upgrading the fuel pump internals would solve the problem or going back to Stage 1 software. 

Yup I do too. My achieved boost is usually 0.3 BAR boost above requested, so if they crank it down a notch I think it will be fine.