RS246.com Forum :: The World's #1 Audi R, S and RS Enthusiast Community

Some of you may be interested in the following.Others will be Very bored Sorry! [img]images/graemlins/sleeping_2.gif[/img]

This is how to check the boost pressure control system.

Carry out road test ensuring full throttle is used from time to time.Thats the bit most of us like!

The measurements must be taken at full throttle
group 115
Zone 1 engine rpm. 2 actual load %. 3 specified pressure mbar. 4 actual pressure mbar.
Specified values for zone 3 is 980 mbar and 4 960-1000

Specified press and actual press may differ by max. + 20
-
Switch to MVblock 117
Check function of throttle pedal by briefly applying full throttle. Shown in zone 2. Spec 0-100 %
Zone 1 rpm. 2 throttle pedal position %. 3 throttle angle %. 4 specified boost pressure mbar.

The specified value in zone 2 must reach 100% when throttle pedal pressed to floor.If not:
Check throttle pedal.

Switch to MVblock 116.
Check correction factors in zones 2 and 4.


Zone 1 rpm. 2 correction factor fuel %. 3 correction factor coolant temp %. 4 correction factor intake air temp %. If a correction factor of less than 0 % is displayed in zone 2, the fuel quality may be incorrect.
Fill up with proper stuff.

If a correction factor of less than 0 % is displayed in zone 3, the coolant temp is too high or the temp sensor G62 is giving false readings to dash and engine ecu. Four wires going to sensor. Two for dash, two for ecu. Both independant so you could have correct reading on gauge, but the engine ecu could be getting an incorrect reading. Best way to check is in dash insert and engine electronic MVblocks and make sure the temps are both the same. New modified sensors are green in colour.

If correction factor of less than 0 % is displayed in zone 4
,the intake air is too hot or the sensor is defective.
Also you could have a high contact resistance in the wires and or plug connectors.

Switch to MVblock 114

Zone 1 Specified load without correction %. 2 specified load with correction %. 3 acual load %. 4 Duty cycle boost pressure control valve N75 %. Specified Value Zone 1-136.0 zone 2-134.3 zone 3-137.5 zone 4-55.2

The load values in zones 1-3 can differ by + 5%
-
If the specified values are not obtained in the MVblocks:
Check boost Pressure sender G31.

Disconnect G31 plug. Check power supply. Probes on pins 1 and 3. Spec 5V approx.If ok good, you dont need a breakout box.
Signal wire.At idle, specified value 1.9V approx. Blip throttle, Value must rise 2.00-3.00 V if not check for open circuit/short to earth or pos.If ok replace G31.

Faults in boost pressure control system.
Boost pressure too low:
Display on 5051-Actual engine load zone 3 less than specified engine load zone 2.Duty cycle display zone 4 approaching 99%.
Possible faults: Boost pressure solenoid valve N75 defective.
Defect in wiring to valve.
Boost pressure control valve stuck open.
Leak between turbo and manifold- should hear hissing.
Turbo defective OOCH. Only change in pairs.

Boost Pressure too high 1):

Display on 5052: Actual engine load zone 3 greater than specified engine load in zone 2. Duty cycle zone 4 approaching 0%.

Possible faults: Vacuum unit for boost pressure control valve defective.
Leak in tubing to vacuum unit for boost pressure control valve N75.
I had a leak in the small plastic Y piece from the N75 valve to the wastegate causing surging when spanked. 80p later sorted.

Boost pressure control valve in turbo stuck closed.

1) When boost pressure is too high the fuel supply is switched off to protect the engine. This results in misfiring at high speeds.

If this is of use to those with vag com let me know.

Another little tip, if the car is down on power and has a slight misfire, check out DTC if it says Bank 1 Bank 2 lean mixture, its the air mass meter. It wont bring the check lamp on either as its not shorted to ground or positive.
Also if your hazard lights work but not the indicators, its your hazard light switch in the centre of the dash thats faulty.
One more if the temp gauge drops suddenly, its your coolant temp sensor, the one down the back of the engine. New modified ones are green. Replace the seal and plastic clip also. The other sensor is for when the coolant gets well hot. It operates the electric coolant pump under the inlet manifold to circulate coolant to the turbos. Hardly ever operates unlike the BAM engine.

All good stoff but do you drink beer and talk about birds and footie ? [img]images/graemlins/033102bigblink_1_prv.gif[/img]

Fine dont complain about paying dealer prices and work it out for yourself. [img]images/graemlins/knob.gif[/img] Was gonna start a feature to help you lot out but you can ram it BYE.

very good info for us DIY guys, thanks Morpheous!

Do you happen to know if we can log EGT's here in Europe. I have tried blocks 34 and 43 iirc, but they dont show any values. Those blocks however function in the US.

damnit, I was just going to ask about EGT logging [img]images/graemlins/smile.gif[/img]

Very good info....As with most I would rather do it myself where ever poss. this does help.......

Fine dont complain about paying dealer prices and work it out for yourself. Was gonna start a feature to help you lot out but you can ram it BYE.

[img]images/graemlins/roflmao.gif[/img]

I was joking.

Ignore David, Morpheous. Just that Yorkshire humour [img]images/graemlins/smile.gif[/img]

good info - hopefully you can keep posting some more. [img]images/graemlins/thumbs.gif[/img]

Excellent info, thanks. I shall try it out. However it seems best to go for a good run whilst logging the blocks rather than try to check them whilst driving. However IIRC VAG-COM can only log 3 blocks at a time. Any advice on which combinations to select for 2 logging runs?

IMO you dont want to log more than one block at time with vag-com. I cant get more than three samples per second logging one block and thats quite good. however its not enough to sample accurate timing but you get an idea whats going on. arp's ecuexplorer would be awesome but they dont have it for my 99 ecu.
If you have consert radio I would suggest buying the hex-com unit as it has worked fine.

the blocks I usually log are:

003: maf , inj timing
115: boost requested , boost actual

when I get my k04s installed I also need to log o2 blocks to see if it get too lean. Egt would be nice but I dont know if its possible with eobd ecus.

Yea we can discover these elusive blocks, not sure if vag com supports where you need to look. Should be able to put something together and explain how the Ex temp system works and what its for..But no time at the mo, going out on the [img]images/graemlins/piss.gif[/img] tonight for a curry with the Ladies.