Problems while mapping the car - boost drop after 5500 rpm

[Jonas_R]

Billman:

So you are saying that it does not work very well with the vmap-d?

[Jonas_R]

RS2 EM, RS2 Injectors, RS2 IC, 7A FPR, RS2 Airbox, PVC system removed and catch tank fitted, Forge DV006, Hohenester hybrid turbo, 3" turbo back system. think that is about it

Cheers

Jonas

[Billman]

For some reason the ECU goes into limp mode. Does your tuner knows what he does? Is he familiar with motronic?

[Jonas_R]

Yes they should be familiar with motronic, they have chipped lots of cars and are regarded as some of the best in Denmark. But it aint showing any fault codes in regards to limp mode. Of course I dont know if it should do that.

But what did you mean with the mapsensor?

[Faheemo]

Here's a log from my zeitronix box ...
Notice how the AFR goes Rich when boost drops off and then it goes lean.
User 1 is the Air flow meters output voltage.
No fault codes - does limp mode spit out any fault codes ?
IT certainly feels like limp mode !

Jonas - our setups quite similar, ive just got bigger 750cc injectors now and a bigger turbo. FPR is standard.
(Ive listed on motorgeek aswell )

[Billman]

You must calibrate the software to accomodate the new map sensor and then tune the rest. The map sensors do not have the same output voltage.

[Jonas_R]

Billman: The Vmap-D mapsensor has something called bosch mode and according to those who makes them, it is a direct replacement. Meaning that you dont have to adjust to a different voltage. If you set it to 3 bar, then it should behave like a 3 bar bosch mapsensor. But I my have misunderstood this? Are you talking in general or about this specific unit?

[Faheemo]

Ive got a 3 bar map sensor aswell, not sure what make.
My tuner has sucessfully tuned the car with the 3071 turbo i previously had.
With the new turbo is wher the problem started, which leads me to believe that its more air and fuel that the setup will need. So i gotta think along those lines.

[dubmeister]

All that the bleed valve does is to fool the wastegate that there is less boost than there is, allowing a higher boost pressure than normal- what pressure is the wastegate set to?
Does the BOV/Dump valve/whatever you call it- leak when you get to higher pressures-is the spring strong enough? I have had high boost pressures lift forge BOVs off its seat causing a small leak.
If the vehicle was being run on the rolling road did the problem start to occur after a number of runs? heat soak and the temps that are generated on the rollers are ridiculous due to the lack of cooling air-is this a factor? Could the boost falling off be because the inlet air has just got too heated?what's the car like on the road?I've had cars with problems on the rollers but been great on the road due just down to the increased cooling.
Are the boost hoses expanding when the boost falls/temps rise?
The ECU has operating limits and will go into a limp mode(as stated before) if these limits are exceeded-when the boost falls off what does the fuelling and ignition do?
This is why tuning a car for higher power is so expensive, every engine is different, even though the specs are very close.You need to check EVERY possibility, even the ones that don't seem relevant
Not to slag off your tuner- but are they familiar with this type of engine? - many claim to be but are not. I am suprised that they haven't given you some possibilities to check if they are specialists.
Anyway good luck and let us know how you get on.

[Faheemo]

The ECU has operating limits and will go into a limp mode(as stated before) if these limits are exceeded-when the boost falls off what does the fuelling and ignition do?
T

just checked with vagcom today, ECU cutting fueling and ignition.

My tuner will sort it out, i have confidance in him.

Jonas - do a log with vag com, and check timing and fueling .

[Jonas_R]

Faheemo:

Dont think I cant check timing and fueling via vagcom. My ECU is from the 3b, dont think they are that advanced

[Billman]

Lets say your car has now a 2.5 Bar Bosch sensor, it means that the programm you are running right now has lets say a voltage of 1,5 Volt for the 2,5 bar. If you install a 3 Bar map it means that the 1.5 Volt is now the 3 Bar. Dont know if i am giving it right but you should adjust your ECU to read the 3 Bar Map correctly.

The V-Map has this Bosch mode for 3 bars. If you install this on a RS2 witch has a 3 Bar Bosch sensor originally it means that it should run as is because the "kennlinie" is the same. If you install a 3 Bar sensor in an ECU with originally 2,5 Bar Map then it must be adjusted.

I may be wrong but to be sure check this out.

[Jonas_R]

Hi,

Ofcourse this has been taking into account I though you meant something else, but both me and my tuners are aware that you have to adjust the car to the 3 bar mapsensor, so that is not the problem.

[Faheemo]

Found the problem on my car ...
Got hold of a boost leak tester and cranked the pressure up to 1.5bar ,
found a few leaks, major one was due to a hose clamp being broke.

feel stupid now that it was such a basic problem, but i must point out that the leaks didnt surface until we jacked the pressure up over 1.4bar !!

Beware the boost leak !!