Throttle pot readings

[driftin jo]

I decided to do some logging in vag com after testing for any fault codes today just to see if anything was a miss.
Well it would seem it is .
I get a reading of 8.3 for throttle angle when sat at idle which I believe is a little high and at WOT it's 99.4 , the thing is is that it does not give the WOT Bin. 10100 ever when I'm getting 99.4 throttle .
The thing that is even more strange is that after studying it and doing more logging it seems to give WOT Bin. 10100 just as I open the throttle then it is back to 100 .

The idle switch is OK and I always get Bin. 10 at idle and Bin. 11 on over run.

I have tested the output voltage between pin 2-3 and I get 4.64v WOT an 0.39v closed, is this OK ?
I have moved the throttle very slowly from rest to WOT and I don't see any odd jumps in voltage.
Any ideas ?

[driftin jo]

This is the log file if anyone wants to see it .

[Flat on my back]

.

If you use an AVO to measure the resistance as you are 's l o w l y' moving the pot shaft you are more likely to spot a break in the track...as opposed to using a DMM.

HTH

[driftin jo]

If you use an AVO to measure the resistance as you are 's l o w l y' moving the pot shaft you are more likely to spot a break in the track...as opposed to using a DMM.

HTH

Yes, I gather that would be better but unfortunately a cant get my hands on one at the Mo

what I really would like to know is are the voltages that I quoted for closed and WOT OK ?

How does the ECU get the 10100 Bin for full throttle, what makes this , is it at a given voltage ?
Has anyone done vag com plot and seen it at full throttle as it should and if so what was the throttle angle in vag com and what was the output voltage measured at full throttle with a DMM ?

[Flat on my back]

.

The 'closed' position voltage looks abit high...would expect <0.1 v as this is s/c or 0 ohms on the pot range.

I expect the BIN is a represetation of the volts as converted by the ecu, the ecu only sees a voltage from the pot and the idle switch open/closed.

Got time to throught it my way?

[driftin jo]

The 'closed' position voltage looks abit high...would expect <0.1 v as this is s/c or 0 ohms on the pot range.

I expect the BIN is a represetation of the volts as converted by the ecu, the ecu only sees a voltage from the pot and the idle switch open/closed.

Got time to throught it my way?

The closed voltage is across pins 2-3 the pot , the idle switch is pins 4-6.
I have checked the switch and its fine , vag com logs also supports that the ECU is getting correct switch input.
I am thinking that the WOT voltage is not high enough to make the ECU think it is at WOT and that's why I don't see the Bin 10100 in the log at WOT.

[S2central.net]

Have you seen the TPS voltage tests on s2central.net ?

Have you also checked that there is a 5V signal into the TPS from the ECU ?

The TPS is just a potentiometer so if the input voltage is too low then the output voltage will be low... SHould see 5V between pins 1&2 and pins 2&3

Resistance across 1&2 in idle position is 1.5-2.6 kohm

Resistance across 2&3 in idle position is 0.75-1.3 kohm which then increases to approx 3.6kohm at full throttle.

[driftin jo]

Have you seen the TPS voltage tests on s2central.net ?

Have you also checked that there is a 5V signal into the TPS from the ECU ?

The TPS is just a potentiometer so if the input voltage is too low then the output voltage will be low... SHould see 5V between pins 1&2 and pins 2&3

Resistance across 1&2 in idle position is 1.5-2.6 kohm

Resistance across 2&3 in idle position is 0.75-1.3 kohm which then increases to approx 3.6kohm at full throttle.

I remember reading somewhere that voltage was more important than what resistance was measured , is this correct ?
Do you think that 4.6 v is low for WOT ?
What about the WOT Bin 10100 what should trigger this ?
If 10100 is not showing up in the logs at WOT does this mean the ECU is thinking it is not at WOT ?
As you can see from my first post i'm getting 99.4 throttle angle at WOT and 8.3 when closed , do you think that these are off a bit ?

[S2central.net]

The angles are in spec... Should be 5-10 at idle and over 90 at WOT...

You should be seeing WOT... unless the signal from MAF is not in spec... The ECU is fussy and checks many things behind the scenes for integrity of sensors.

What is your altitude sensor reading for ambient pressure on VAGCOM ?

Aren't you getting max boost - is that the purpose of this investigation ?

[driftin jo]

The angles are in spec... Should be 5-10 at idle and over 90 at WOT...

You should be seeing WOT... unless the signal from MAF is not in spec... The ECU is fussy and checks many things behind the scenes for integrity of sensors.

What is your altitude sensor reading for ambient pressure on VAGCOM ?

Aren't you getting max boost - is that the purpose of this investigation ?

For a wile I have felt that it was not making the boost it should , with your home fries it should make 1.4 bar ,that should be about 20.3 psi on my gauge. I only get about 16.5-18 psi, this isn't a mile off and I thought it may well be due to temp correction lowering the boost.
After driving it the other day when it was quite warm I was expecting the boost to go up a bit but it didn't.
I have changed all the hoses and tested for boost leaks and there are none, so that is why I decided to look at electronic side of things .
My pressure in vag com was 1025 mb today so that is fine.
I have a few mass air flow meters , a almost new rs2 one that is on the car now and a new aby one a bought from vag parts just before they stopped trading . I think I will try that one tomorrow to see if there is any difference , but when I fitted the rs2 one on Friday last week there was no change in anything boost wise .

What other things could make the ECU not show 10100 in vag com at WOT ?

Did you also read in my first post that I get 10100 in the logs just as I come off idle, just for a split second then back to 100. ?

[driftin jo]

Have you seen the TPS voltage tests on s2central.net ?

Have you also checked that there is a 5V signal into the TPS from the ECU ?

The TPS is just a potentiometer so if the input voltage is too low then the output voltage will be low... SHould see 5V between pins 1&2 and pins 2&3

Resistance across 1&2 in idle position is 1.5-2.6 kohm

Resistance across 2&3 in idle position is 0.75-1.3 kohm which then increases to approx 3.6kohm at full throttle.

Between terminals 1 & 2 I'm getting 4.97 v
Between terminals 2 & 3 at WOT I'm getting 4.6 v and if I measure resistance I get 2660 ohms.
do you think this is the problem ? I read it should be about 3600 ohms at WOT.

[S2central.net]

Sounds too low alright... see if you can get a spare throttle pot to test - they are expensive from new.

I can test mine later tonight if that helps. Maybe a few other folk can do that resistance test across pins 2 & 3 - its a bit fiddly though to do with one pair of hands - unless you have a breakout box

[driftin jo]

Sounds too low alright... see if you can get a spare throttle pot to test - they are expensive from new.

I can test mine later tonight if that helps. Maybe a few other folk can do that resistance test across pins 2 & 3 - its a bit fiddly though to do with one pair of hands - unless you have a breakout box

That would be good , if you could .
Yes you need to be good with chop sticks to test the throttle pot
i.e. holding both DMM probes in place with one hand wile the other works the throttle.

It would be good if we could establish all the criteria the ECU needs to give WOT Bin 10100.

the thing that is puzzling me is that although I only have 2660 ohms and 4.6 v output at WOT
vag com gets 99.4 throttle angle but does not give BIN 10100.
maybe you are right about it being something else that is preventing this other than the throttle pot.

[driftin jo]

Any results from testing ?

[driftin jo]

Got a bit of time yesterday and decided to take the throttle pot off, anyway a few things I found are I bit strange.
The Bosch part number on mine was 0 280 120 431 and the Audi number was 078 133 154 .

On S2 central it says the part number for the ABY is 034 133 154 .
The other thing I noticed was that the Bosch part number on mine was the same as the Bosch part number for the 3B one on S2 central.
So I then concluded that someone in the past had fitted a 3B one to my ABY at some point before I bought the car.
This seemed to make sense and I thought I had found my problem until I looked at ETKA !!
ETKA lists 034 133 154 F for the 3B one and 078 133 154 for the ABY.

So according to ETKA the one I have is correct, now I know that this number may have superseded the number for the ABY one on s2 central but that's not just that, because the Bosch part number for the 3B one on S2 central is 0 280 120 431 and this is the same number that is on mine along with the Audi number 078 133 154.

Something is not right here unless the 3b and ABY are the same , and I remember reading that they were not interchangeable .

Does anyone have a 3B one with the Audi number 034 133 154 F and if so what is the Bosch part number on it ?
If it is 0 280 120 431 then I think that the 3B and ABY are the same part from Bosch and its just Audi that changed the numbers unless ETKA is wrong.
Can anyone shed any light on this ?