Cruise control effecting throttle response & power delivery

[vrs180]

Hi guys.

 

In early Sept 2015 I fitted a brand new Garrett GT1749VB (PD160) turbocharger to my wife's Fabia vRS SE after the thrust bearings failed within the Std KKK BV39 turbo.

The car was (conservatively) custom mapped to 195bhp @ 3700rpm & 410Nm @ 2200rpm, which is more than enough for our needs and totally transformed our enjoyment of the car.

With the new turbo fitted the engine ran much smoother, had better throttle response and a new found eagerness to pull hard from any rev's with only a very small press on the throttle pedal, in fact you found yourself having to lift off the throttle quite a lot of the time.

However a few weeks later the engine ran less smooth and the improved throttle response was gone.....sure it would still go well (very well in fact) but it felt like you were having to work harder at the throttle to get the same performance out of the engine.

I checked for faults with VAG COM on several occasions and found nothing and also got the car up on ramps and couldn't find anything amiss, which is pretty much what I expected (I'm a very experienced mechanic (all be it on trucks) and a perfectionist at every thing I do to the extent I even made guides on my lathe to ensure the new turbo aligned perfectly with the cylinder head exhaust ports).

 

My wife thought it was just us who had perhaps got used to the way it drives, but just before the Christmas break I decided to turn the cruise control to the "off" position while we were out driving in the car, and immediately the previously lost smoothness, improved throttle response and increased pulling power returned, and has remained to date.

 

I have left the cruise control in the "off" position, were it will remain until I get a better understanding as to what is happening.

 

So, has anyone come across this before or any thoughts on why this is happening ????

 

Thanks, Bill.     

[poiuytre111]

Pure speculation but.... the cruise control acts through the ecu and not the physical throttle (e.g. via a bellows or whatever). Is it possible that the way it works is interacting with elements of the remap ? I would be tempted to ask whoever created the map.

[SKYHAWK]

mine got cruise and been mapped and drives the same wether its on or off

[Tech1e]

Very odd as nothing should change just because the system is switched on. Although APR used to have the option of switching maps via the cruise control switch iirc so maybe something is a miss there. I'd check with your remapper.

[vrs180]

Thank you guys

Interesting that the cruise control could be used to switch maps, I never new that, thanks.

I think we will run the car for the next few months with the cruise control turned off and see if everything stays the same as it is now and perhaps confirm nothing is wrong with the car, then talk to the guy who mapped it.

Bill.