No boost after engine/turbo upgrade

[gmac78]

I'm holding off opening up the ECU and changing the chips unless i have to. The more it is opened and closed the more potential for some something to be damaged i guess. But yeh it's a good sanity check.

I guess i'll trace the wiring from the sensor back to the ECU so see if theres any issues. If the G40 is failing where is the best place to buy one? Are 3B and ABY sensor the same part number?

[gmac78]

I've only just bought the V stream chips and R201 resistor from S2Central. We were in discussion regarding my setup so not sure which ones he supplied. Having the R201 resistor was a requirement for the software he supplied though.

[twoqu]

Well you say that the problem started when you swopped chips so that looks a potential clue. Whether its a SW or HW issue needs to be eliminated. Is the V stream a RS2 version or for an S2 RS2 conversion. There will be a difference to account for that resistor which then needs RS2 base SW not S2 base.
If you have the old chips you could just swap them back as a sanity check!

[gmac78]

I didn't check timing today as it is only been a few weeks since all that was put back together. It was all spot on at the time so doubt anything has gone wrong there, i used a new crankshaft sprocket so hoping thats not failed already?!!

N75 is all plumbed up correctly too. Previously the car could be idling/revved and no blink light coming on. Now as soon as you start the car and rev it up to around 3-4k the blink light will illuminate and throw the G40 code. The hall sensor could be failing or the wiring to it loose somewhere but i've just checked the 3B to ABY pin out and pins 8 & 12 are not disturbed during the process so they should be ok. I'll need to double check though.

[gmac78]

Hi Guys,

Didn't get much of a chance to play with it today but did try a few things.

Started the car but was slow to spring in to life again, the car has never been like this, always started first turn.

What might be of interest is that i had the ECU out a few days ago getting the correct R201 resistor fitted, as previously i had two resistors in series, which measured 5.6k ohms instead of the correct one which measures 5.5k ohms. The difference is small but thought it best to put the correct resistor in for peace of mind. At the same this was getting done a wire to the 3 MAP sensor had broken it's solder and needed repairing. All went well according to the TV repair guy doing the soldering, it was him that had fitted the original two resistors and MAP sensor a couple of months back.

It was after refitting the ECU with RS2 V STREAM chips instead off the TS Tuning ones that were in it previously, that this problem has started. I also fitted the correct RS2 injectors instead off the 034 replicas which were in it. I thought i may as well put the correct injectors since them were sitting on shelf.

Anyhow since doing all of this i am now getting a fault code which is activating the blink light on the dash, and i'm guessing is the cause of the no boost issue??

The fault code stored in VCDS is
00515 Camshaft position Hall sensor G40
01-10 Signal Shorted to plus- Intermittent

During the few spins i had of it today it was once boosted up to 1 bar, this was with the MFTS still connected.

Disconnected MFTS and could not get any more than spring pressure boost.

My paranoid mind is thinking something could have been damaged in the ECU whilst fitting the R201 resistor and re-soldering the wire on the MAP sensor?

Up until this work a couple of days ago the car would start first turn, and could be revved no bother without any blink codes activating. I haven't touched anything else on the car.

What do you reckon to that guys? Where next?

Possible loose wire on the ECU following the 3B to ABY conversion. Doing that pin swap can be quite tricky! Or is there something else more obvious?

Thanks for all your input guys.

[EBR]

Are you using an OE crank pulley for the timing belt? I had an OE crank pulley that broke and turned a few degrees on the crank. When it happens the hall sender on the head doesn't sync with the one on the flywheel and that makes the car go into safe mode. When it happened on my car everything seemed normal, but it went into safe mode when it was reved over approx 4k rpm.

[mike74]

Are you sure the N75 is plumbed up correctly?
Another thing to check is the barometric sensor (assuming 3B's had it?) ala:

http://www.s2forum.com/forum/showthread.php?t=2899&highlight=barometric+ohms

[newsh]

Is your dizzy and cam timing definitely spot on? Everything on the marks?

Check WGFV is working and not stuck. (Open bonnet, blip the throttle by hand and you should hear/feel the WGFV clicking)

[Rusty]

This was an issue on a mate's car and the previous owner had replaced half of the car to try and cure it

[Error404]

Mine was playing up a while back for no apparent reason so I disconnected the signal to the ECU at the T8 connector on the bulkhead
IMHO if you are dumb enough not to recognise an overheating engine & back off the loud pedal you deserve a fooked engine

[UrS4boy]

F76 Multifunction Temperature Switch R&R Info (with Cross Links to G62 Coolant Temp S

Could try the MFTS, was working ok previously but you never know. Take it they don't throw codes?

Nope. And a failed one fails safe, "telling" the non-AAN (i.e. 3B, ABY and ADU) ECU that coolant temps are hot, leading the ECU to shut down active boost control, i.e. WG spring pressure only.

"The F76 Multifunction temperature sender has different functions in the ABY and ADU than the AAN. For all three, the MFTS is the sender for the temperature gauge in the instrument cluster. On the ABY/ADU, the MFTS is also connected to the ECU via pin 46 of the T55 ECU connector. Using this pin as a high temp alarm (> 119 C) - the ECU cuts off active boost control as a safety measure. However, for the AAN, pin 46 is not used, as indicated in this Motronic 20VT AAN pin-out. On the AAN, the MFTS F76/R pin connects to is the HVAC/climate system to shut off the compressor during such high temperatures. In addition, the MFTS is connected to the coolant temperature gauge."

REFERENCE: http://forums.quattroworld.com/s4s6/msgs/22584.phtml

[gmac78]

Had a quick look at the inlet manifold grounds, seemed tight enough. Could try the MFTS, was working ok previously but you never know. Take it they don't throw codes?

[Error404]

Unplug MFTS and have another try

VSS behind stereo is only there for GALA so no problems there, as long as the ECU has its feed

[newsh]

Check your ground wires are good and tight to the inlet manifold

[gmac78]

V Stream from S2Central.