Rough/boost on idle
Posted: Tue Apr 21, 2020 10:37 am
Hi all,
I own a tuned (RTMG more than 5 years now) Polo 6R GTI '12 CAVE engine (full 70mm exhaust with free-flowing 200cell cat, Wagner intercooler, R8 coils, forge blowoff valve, oil catch can).
A few months now I randomly have increased boost/rough on idle (it is not happening all the time). I don't have any error codes at all, I don't have any power loss when pushing it to the limits, I did my service a month ago (sparks,oil,oil filter replaced), we did engine compression test and everything seems fine, we did air test to PCV valve, we checked the tubes that goes to turbo, bov, map sensor etc.
I removed the PCV valve and cover the intake manifold to PCV output to check if something else is happening to PCV (pcv delete). The things are a bit better but now it is doing it every time I stop the car(crossroads - red light) and not randomly on idle with PCV installed.
I use only 98 and 100 octane BP or Shell fuels.
Most of the time will stop doing it by itself or when I start moving again.
Basically we checked everything that might related with it but still nothing.
3 things happen every time this occurs.
1. Bad smell from exhaust
2. Popping sounds from exhaust, usually when I release the gas pedal and leave it to slide.
3. Short term fuel trims goes to 25 and long term trims to -16/-17
I heard about MAP sensor, brake booster, coils, throttle valve and lambda sensor but as I said at the beginning no error on VCDS.
Any ideas what that might be? I assume a vacuum leak summer or engine struggling to breath on low RPMs.
https://www.dropbox.com/s/1p939lnfp68wa ... 0.mp4?dl=0" onclick="window.open(this.href);return false;
https://www.dropbox.com/s/ah7ed5kre8gp7 ... 1.mp4?dl=0" onclick="window.open(this.href);return false;
Thanks in advance
I own a tuned (RTMG more than 5 years now) Polo 6R GTI '12 CAVE engine (full 70mm exhaust with free-flowing 200cell cat, Wagner intercooler, R8 coils, forge blowoff valve, oil catch can).
A few months now I randomly have increased boost/rough on idle (it is not happening all the time). I don't have any error codes at all, I don't have any power loss when pushing it to the limits, I did my service a month ago (sparks,oil,oil filter replaced), we did engine compression test and everything seems fine, we did air test to PCV valve, we checked the tubes that goes to turbo, bov, map sensor etc.
I removed the PCV valve and cover the intake manifold to PCV output to check if something else is happening to PCV (pcv delete). The things are a bit better but now it is doing it every time I stop the car(crossroads - red light) and not randomly on idle with PCV installed.
I use only 98 and 100 octane BP or Shell fuels.
Most of the time will stop doing it by itself or when I start moving again.
Basically we checked everything that might related with it but still nothing.
3 things happen every time this occurs.
1. Bad smell from exhaust
2. Popping sounds from exhaust, usually when I release the gas pedal and leave it to slide.
3. Short term fuel trims goes to 25 and long term trims to -16/-17
I heard about MAP sensor, brake booster, coils, throttle valve and lambda sensor but as I said at the beginning no error on VCDS.
Any ideas what that might be? I assume a vacuum leak summer or engine struggling to breath on low RPMs.
https://www.dropbox.com/s/1p939lnfp68wa ... 0.mp4?dl=0" onclick="window.open(this.href);return false;
https://www.dropbox.com/s/ah7ed5kre8gp7 ... 1.mp4?dl=0" onclick="window.open(this.href);return false;
Thanks in advance