WOT Fault Resolved

[GandalfS6]

James, it sounds like quite a nifty idea. The problem is that I do live at high altitude (4000 feet) and I am a bit worried about lying to the ecu when I am in fact at altitude?

[newsh]

So, does a 3B have one of these things?

[S2central.net]

Oh yes - its fitted to RR, 3B, AAN, ABY, ADU for definite.


Paul

[GandalfS6]

How to save 40 quid

How to save 40 quid (or 98 in my case)? My brother-in-law, who is a computer technician) had a look at the F96 on my car. I told him what the resistance was that the people with working F96's got. He opened it up and bent the piece of metal at the top (shown with an arrow) until the resistance between 1 and 2 was about 1200 Ohm. We refitted the F96 and viola, VAGCOM has the right air pressure! (Ok it is about 12 mBar out but that is close enough.) I checked it again today with actual atmospheric pressure 7 mBar higher and VAGCOM showed exactly the same increase. I guess the resistance goes out over time, but the sensor is still working.

This is what you do:

1) Remove the F96 from the car.
2) There are 4 clips that hold the cover. Clean out the sealant on then and unclip the cover.
3) Bend the straight piece of metal at the top upwards (arrow in the photo) - check the resistance and keep on bending slightly (it is quite sensiitive) until you get about 1200 Ohm between contact 1 and 2 (2 & 3 and 1 & 3 can't be changed). You can see in the photo that this bit is slightly bent from his procedure.
4) Clip the cover back on.
5) Fit the F96 and if you have access to a VAGCOM check the pressure reading and compare with actual readings. If it is still too far out, repeat the process untill the VAGCOM reading is close enough to actual.

My car is now getting WOT and is boosting 1.8 Bar (I am estimating as my Guage is a 1.5 Bar guage). The car is absolutly flying. But I am a bit worried that 1.8 Bar might be too much?

[S2central.net]

Send that man a 'Team Bodge' sticker !

Nice work - if a bit hairy - the altitude sensor is designed for geography like yours - in the mountains I mean. Keep an eye on the real world ambient pressure and what F96 tells you.


Paul

[martinjs]

Paul, what will be the effects on a 3b if this sensor is dodgy?

[S2central.net]

Martin - Whilst the 3B doesn't have an overboost map, or dynamic altitude compensation like the AAN/ABY/ADU, F96 is used by the E3B CU to establish ambient pressure. This would require testing on a 3B, but I suspect that erronous values from F96 could fake the ECU into reducing or increasing permitted boost.


Paul

[martinjs]

I'll try and take some readings then to compare against the aby results.

[Berra_200]

Here´s my 3b readings.

1---2 0,501 K Ohm
1---3 2,097 K Ohm
2---3 2,414 K Ohm

Measured at 770mm = 1.026582 Bar

My car has sometimes overboost fuelpump cut off problems at cold/rain temperatures.
Time to bend and try again

After some bending on the metall inside

1---2 1,145 K Ohm
1---3 2,576 K Ohm
2---3 2,410 K Ohm

[Berra_200]

Report:
I belive the changes made my boost a little lower, as it should.
It was a little bit high before, 0.8 to 0.9 now it is like 0.7 to 0.8
With the unchipped ECU.

This changes did not affect my fuelpump cut off problem with the modified ECU, chip + 250Kpa MAP.

My fuelpump cut off problem was because of a dirty MAF.
My error code was: Maximum boost pressure Exceeded (intermittent).
The MAF wire was brown on the "facing filter side" but clean on the other side.
I had to remove the screens to really se it.

Over and out.

[porkkis]

Is this sensor being used with MTM software also? I have slightly too much boost. It's around 1.6, should be more like 1,4.

Surely you think that too much boost is something too weird to be included in our vocabulary but I'm a bit worried about the stock rods as this gives me 500Nm at 3krpm - certified on the rollers.

[Berra_200]

Hi!


Yes it is, but it should not affect boost pressure at sea level places, it should only lower your boost above 1000 meter (333 feet) according to SSP111 document. But it did in fact affect my boost a little bit, if you look at the schematics you will see that this sensor is connected to the throttle sensor also and I believe that is the answer to my little different boost levels.

500Nm would be nice as long as the rods stays in the block right? :-)
I don’t have the knowledge of your specific setup or chip config but if it was my motor I would try to disconnect the electrical connector on N75 (boost regulation valve) take the cars for a test drive and record the boost value
It should be aprox 0.4 Bar if you have an original wastegate spring that is not tampered with. I know that some MTM chip may require different springs or so, but if not, you should adjust your spring to 0,4Bar

Think of it this way: your MAP senor is getting the boost info, it reports to ECU(voltage level), ECU looks into boost map (in chip) and ECU puts out a frequency voltage on the N75 valve. I don’t think the ECU has any leering or adaptive function on this regulation so if your N75 valve is oscillating with a fixed value calculated in the ECU for your specific throttle angle, intake temp and so on it will NOT be the right outcome with the wrong wastegate spring.
Conclusion: to hard spring to much boost, chip must be written with a harder spring in mind if it should work.

Of coarse if hoses or N75 is leaking it will be wrong to.


Please correct me if i´m wrong!

[Greg_S]

Berra, the stock WG spring pressure is higher than 0.4 bar. Its either 0.6 or 0.8 bar, cant remember which off the top of my head though.

Greg

[Berra_200]

Is it?? That will not make sense as the wastegate opens at 0.4 Bar without the connector on the N75 or is it a different rate spring in S2 than 200 20V 3B?

Please try with your car and we will have a S2 reference.

[GandalfS6]

On my car (ADU) it is 0.4 Bar max if I disconnect the WGFV.

Is it?? That will not make sense as the wastegate opens at 0.4 Bar without the connector on the N75 or is it a different rate spring in S2 than 200 20V 3B?

Please try with your car and we will have a S2 reference.