I did a wide open throttle test on my VRS yesterday (accelerate in 3rd from approx. 2000rpm to red line) and this is a graph showing the results I got:

 

 

the pattern seems a bit alarming to me as I've got this one from the hidden-power website that shows what a standard graph should look like and mine's completely different:

 

 

 

 

as far as I know my car is stock (no remap) but it has the engine from a golf GT TDI, could this cause these results? or could there be another reason for the strange results?

Edited 25 May, 201412 yr by soul snatcher24

From my limited understanding your car is over boosting a lot and for a long time.

Looks like your boost is actually exceeding the ability of the 3 bar MAP sensor to read, peaking at about 3.1 bar by the look of it, I would say your VNT mechanism is stuck.

The standard 3bar map sensor can only read upto 2bar positive pressure, and down to 1bar vacuum.

The standard 3bar map sensor can only read upto 2bar positive pressure, and down to 1bar vacuum.

 

Negative captain, the standard sensor reads from 0 to 3 bar, 0 bar is a perfect vacuum, 1 bar is atmospheric pressure, any more than 1 bar is boost, which is exactly what I said.

Negative captain, the standard sensor reads from 0 to 3 bar, 0 bar is a perfect vacuum, 1 bar is atmospheric pressure, any more than 1 bar is boost, which is exactly what I said.

yeah, but in car turbo charger talk 'peaking at' is normally used to talk about the positive pressure created, as per a boost gauge.

ie what looks like 2.1bar on the above car.

The graph the OP posted is clearly calibrated in millibar, I was merely pointing out that the manifold absolute pressure is exceeding the measurement range of the MAP sensor.

 

Engineers talk differently about cars than drivers do for a reason.

Anyway it looks to me like you have a map in there by that, as the requested boost is higher than normal , the vnt is sticking a bit causing the overboost too.

hi guys

 

thanks for all your help, do you think the actuator could need adjusting or is the VNT system just clogged with carbon?

 

I'm going to take a look at the vacuum line and actuator today, how can I tell if it isn't adjusted properly? or actuator isn't working properly?

 

I don't really fancy getting the turbo off as I will need the car to get me to work tomorrow morning

 

thanks again guys

Never tried it myself but the Mr.Muscle Oven Cleaner de-coke is prob the easiest to try first.

Thread's on here about it and how to do it.

Prob not recommended by our forum engineer though..............

It does work but the innotec cleaner kit is a safer option.

Surprised it isn't dropping in to limp mode with that much overboost!

Jason

 

My BLT dosent as when it detects overboost it just increses IQ using the MAP instead of MAF

Really? Anything to not kill overboost can't be good for turbo life.

it is strange that it doesn't but as I've read on another forum it seems like if the veins are stuck closed (underboost) will flip it into limp mode but if the veins are stuck open (overboost) it won't

 

however it's odd that after putting on such a clean (almost new looking) turbo as part of my engine swap, that it could be sticking after just a couple of months driving. I unbolted the actuator on Sunday and the veins seem to be moving very freely so I think I will take it off and see what is going on inside before I put any cleaner through it, but the next chance I will get for that will be Saturday

 

here's the thread (very detailed) in case anyone is interested, it does also mention the innotec cleaning kit:

 

http://uk-mkivs.net/topic/34834-vnt-tdi-turbo-how-to-adjust-actuator-cure-boost-problems/

 

some of the bits in that thread are specific to golf turbo so may not translate to fabia exactly but it helped me

Edited 27 May, 201412 yr by soul snatcher24