MK5 Golf GTI
All Things Mk5 => How to Guides / Troubleshooting => Topic started by: 416stroker on February 18, 2021, 02:45:56 am
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Is it normal for it to be 1010mbar at all times ad idle specified is calling for less and key on car off ?
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Yep that's right. 1000mb +/- a bit is atmospheric pressure. Check a weather forecast for actual pressure today. The reading you're taking will vary day-to-day.
To work your actual boost pressure out you need to take the boost reading (assuming from vcds or similar) and subtract the atmospheric pressure.
e.g. a stage 1 car will peak on VCDS during a 3rd/4th gear pull at around 2400-2500 mbar, which works out to be 1.4-1.5 bar. Stock car is more like a peak vcds reading of 1800mbar = 0.8 bar.
A good resource for loggin boost:
http://www.vaglinks.com/OBDII/Vag-com_Data_Logging_And_Graphing.pdf
I tend to log boost, mass air flow and a couple other things like this a few times a year. It's a good way of getting a snapshot view of the health of the engine/turbo boost pipes etc. Good to compare current logs with past ones too.
..probably too much information :signLOL:
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You should be able to graph logs here.
More info
https://www.mk5golfgti.co.uk/forum/index.php/topic,88889.msg900790.html#msg900790
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Thankyou for the reply’s . This helps tremendously it was confusing me some
I’m trying to track down some issues with the car and no faults . But N75 is staying at zero from what I can tell . LPFP looks really week about 4 bar at all times. Waiting on my Ross-tech delivery . I had lots of issues with the MAP and water as of late. Just trying to make sure it’s reading correctly after repairing the harness. Ive been using a OBD eleven I feel it doesn’t report a lot of info on this car.
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Yep, as f00lgee said, 1000mb at idle is normal.......only because the MAP sensor is upstream of the throttle. If the MAP sensor was in the intake plenum where it would normally live on a turbo engine, (downstream of the throttle plate) it would also show vacuum. VAG only use the MAP sensor for boost reference, and the MAF sensor for load.
The low pressure pump varies from 3.5 to 6 bar under normal conditions. If it's stuck on 4 bar permanently, that isn't right. Maybe try replacing the fuel filter as the pressure regulator is built into it. It's not uncommon for that to fail.