Vw Corrado G60
My Supercharged Karmann VdubGuides > Boost Check Via MFA
This guide will show you how to check boost levels of your Corrado G60 via the MFA (Multi function on board computer) without using a boost gauge. If you have any questions you can leave a comment .
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No boost gauge and need to check boost levels in your Corrado G60? No problem. The MFA on board computer of the Corrado allows us to see inlet manifold pressure. This allows us to know what sort of condition the G-lader supercharger is in, and allows us to diagnose possible issues such as boost leaks and over boosting.
NOTE: This guide asumes standard cylinder head (No porting/polishing) and standard camshaft. Reason being that anything other than standard will vary the readings.
NOTE: Using an actual boost gauge, ideally combined with a VAC gauge is of course the best way to monitor boost levels, and to monitor the health of the intake system. This guide may be edited to add such details, or a separate one may be created...
BUY: Boost gauge
Tools and parts required
Tools required
- No tools required
Parts required
- No parts required
MFA boost check mode
- Ignition on, and MFA stalk in position 2
- Hold in the 'Select' button on the end of the stalk...
- While holding in the 'Select' button, turn off the ignition and start the car straight away
- Release the 'Select' button and press it once
-
You should now see a reading on the MFA screen on the dials.
Readings of 550-650, fluctuating with idle are fine. Anything higher than 650 means a possible vacuum leak on the inlet side (From supercharger outlet to inlet manifold). Anything too much lower than 550 is a sign of possibly having too much timing advance.
Checking boost levels
- Run and drive your Corrado up to temperature
- In a safe place, run up to redline in third or fourth gear and note down the highest number you see on the MFA display
- 200 = 23.7 = Vacuum
- 400 = 17.8 = Vacuum
- 600 = 11.9 = Vacuum
- 800 = 5.9 = Vacuum
- 1000 = 0 = Atmospheric pressure/No boost
- 1200 = 2.9 PSI = Large boost leak or damaged g-lader
- 1400 = 5.8 PSI = Large boost leak or damaged g-lader
- 1600 = 8.7 PSI = Boost leak or tired/worn g-lader apex seals
- 1800 = 11.6 PSI = Healthy g-lader on standard pully
- 2000 = 14.5 PSI = Healthy g-lader on 68mm pully
- 2200 = 17.4 PSI = See notes below
Using the numbers below you can cross reference your readings.
Readings of 550-650, fluctuating with idle are fine. Anything higher than 650 means a possible vacuum leak on the inlet side (From supercharger outlet to inlet manifold). Anything too much lower than 550 is a sign of possibly having too much timing advance.
A standard Corrado G60, in good working order should see readings of around 1750 equaling around 11 PSI.
NOTE: Without additional modification you will not see above 15 PSI, this is because the ISV (Idle stabilisation valve) in conjunction with the MAP sensor in the ECU are programmed to vent boost at this point. The reason for this is that the MAP sensor can not read any further.
Running higher than 15 PSI may cause a lean fuel mixture which is dangerous.
With a custom ECU chip and a custom MAP sensor you can fuel the car correctly for more than 15 PSI. You can also then look at rerouting the ISV.
There may be times where you do see over 15 PSI without modification, and this can suggest a worn/sticking ISV, or an electrical issue regards the various sensors.
Last update: Mon, April 04. 2022
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