Throttle Position Sensor

[jonathanfenton]

Hello All,
The Mrs was reporting that her car felt "weird". Like the throttle was different. I took it for a spin and it drove fine to me. I did a fault code scan and it came up with Throttle Position Sensor intermittent. Cleared the code and took it for another drive and it came back. Its a cable throttle so not sure if the ECU needs to know where the throttle is as there is the mass air flow meter etc so it knows the engine is hungry. All i can put it down to is it helps anticipate what the throttle body will require :S. Any more information on prices etc would be appreciated. I am pretty sure its the sensor sat on the throttle body?. I think its ready for a clean!. Any one got a link to the throttle body alignment stages from ross link?

Thanks to all who can help! :biglaugh:

[Crasher]

Which car as it can’t be the A3 2.0 Sportback140 Sport?

[jonathanfenton]

lol sorry no thats mine. She has a 1.8t Audi A4 B5 on an N Plate.

[Crasher]

Do you have the cars engine code (AEB?) and the fault code number?

[jonathanfenton]

AEB030111

Fault Code 16505

thanks

[jonathanfenton]

Took the throttle body off and cleaned it with brake cleaner and scrubbed all the carbon off greased up the throttle return spring and put it all back togeather and ran it up and down the road and it seems fine if not a little more responcesive... will have to keep an eye out on the code it keeps throwing back. I actually ran it with the cable unplugged and it still ran great. Not sure if these sensors do much!

[Crasher]

16505 Plausibility of throttle valve potentiometer

1) Moisture or corrosion in plug connection at potentiometer
2) Potentiometer defective


Causes

1) Slight misfiring under acceleration
2) Idling speed control behaviour unstable
3) Load change jolt on accelerator release
4) Restriction of boost pressure (AEB engine only)

Test

Check throttle valve control part

Perform Basic Setting 04, group 098

[jonathanfenton]

Please could you elaborate on

3) Load change jolt on accelerator release

What does it mean by jolt? It is prone to hesitating before dropping when dipping the clutch when stopping

[Crasher]

That was cut and pasted out of the manual, basically when coming off the throttle to change gear the car can jolt.

[jonathanfenton]

Well i finally got round to changing the throttle body (to refurbished one off Ignition Parts £93) as the old problems it had returned. My laptop with my vagcom died so couldn't do a throttle body adaptation so just took it on a few mile drive. Got it warmed up and gunned it down a few straights and it seems to drive fine. Am i right in thinking that a throttle body adaptation just cuts the learning time down or do i still need to do it? Its 95% there but can still sometimes idle just over 1000 instead of 800 will it get better with time?

[jonathanfenton]

Got my laptop working again but when i go to 098 it says N/A in green? :S wont do an adaptation... quiet confused now as what to do. Spoke to my local VG specialist and they said it needs an initial alignment then it should be ok... He said they stopped using VAGCOM as it wasnt very reliable... i have heard something about readiness procedure to make the Throttle Body ready for adaptation but im not too sure what there is to get ready?

[Crasher]

As far as I am concerned you have to perform the adaptation.

[adamss24]

Try Basic setings block 060. If not available then your Throttle body only has a Iddle control valve so it does not need adaptation but the ISV might be faulty... Reading ross tech wiki is a good ideea...

[jonathanfenton]

I tried block 60 and it says not available and on 98 it says N/A in the adaptation block. Spoke to my local VAG specialist and they said it defiantly has to be adapted :-s and it doesn't have the throttle stableisation valve

[adamss24]

Follow this link. remember you need to go to measuring blocks THEN SWITCH to basic Settings for the adaptation to run it's course. If it still does not then there's a fault with your "new" throttle body !
http://www.ross-tech.com/vag-com/cars/audiB5.html

[jonathanfenton]

Volkservice have said they will try it on their computer on wednesday so i will let you know how i get on. The TB i baught has a 2 year warranty so im not too fussed. Also i tried to adapt the old one and it did the same thing so i am guessing that my VAGCOM isnt working right.

[jonathanfenton]

Well had it adapted and its still not perfect... when you rev it up it seems to drop down in stages? When you gun it in a high gear at low revs it seems to struggle when the boost starts to come on. If i start in 1st gear and go up normally it seems fine. When it does hesitate in higher gears it puts a code in the ECU "Thottle Position Senor Signal too low intermittent". The last throttle body flagged up that error too so not too sure what else I can do now to smooth everything out.

Tried Adapting it the manual way:
Completed the steps below:
Adapted the throttle:- by disconnecting the battery and shorting
the terminals together, turn the ignition on for about 1 minute, [this is
called doing a capacitance discharge], turn off and reconnect battery.
Now turn on ignition for about 30 seconds / 1 minute. BUT DO NOT START ENGINE OR TOUCH ACCELERATOR. You should hear and possibly see the adaption in the first 20 seconds. Start the engine and it should be adapted.

I heard the throttle body adapt and it did run smoother and power was nicer... Idle still isnt right and was hunting slightly... but the vag specilist said it takes time for it to fully set its self up and takes 10-20 miles of driving for it to settle down ie expect it to rev slightly when dipping the clutch at lights etc.
All was going ok until i gave it full throttle at low revs in a high gear and it hesitated and flaged up the error again!

Cleared the DTC and then:

I checked the voltages given out by the throttle body

Full Throttle 0.040V
Idle Engine OFF 4.400V
Idle Engine On 4.520V

Am I missing something obvious now?
Does the MAF Sensor have any diagnostics i can do?
Any help would be appreciated!

[Crasher]

What is the fault code number you are getting?

[jonathanfenton]

Same as last TB. Fault Code 16505. Im just going to quickly double check it back in a se.

[jonathanfenton]

Sorry it was 16506 Throttle Position Sensor (G69) Signal too low. p0122--35-10--Intermittant. Could it be the throttle cable is too tight and is pulling the throttle body too open? I suppose if i slacken it some more i will have to re-adapt the throttle body so it knows its new positions...

[Crasher]

16506 Throttle valve potentiometer: signal too small

Possible cause

Short to ground in potentiometer or in wiring connection between potentiometer and engine ECU

Effects

- Slight misfiring under acceleration
- Load change jolt on accelerator release
- Restriction of boost pressure (AEB engine only)

Solution

Rectify short circuit according to current flow diagram

[jonathanfenton]

Thanks crasher.

Slackened off throttle cable and readapted the throttle body. Now my figures show as:
4.520 idle while running
4.4 idle whilst off
0.1v whilst fully open (Normal full throttle pedal pressure)
0.08v whilst fully open (foot mashed into carpet)

I presume the fault code is stored when it gets below 0.07 (ish)

Doesn't seem to bring code back? (16506) so could suggest that it doesn't like being too open. Will have to monitor situation over next few days but appears to have solved problem of full throttle causing semi limp mode.
All that i can see wrong now is that still when coming off the power just as its starting to boost it judders slightly... but i have read that they spend the next few trips learning?? What are the symptoms of the mass airflow meter not on top form?

[Crasher]

What are the symptoms of the mass airflow meter not on top form?

Various, I fit a new genuine exchange unit to see if it makes a difference.

[jonathanfenton]

What are the chances of you knowing what the full throttle Voltage should be?

[Crasher]

Not as easy as that, PM me your email.

[jonathanfenton]

Sent thanks. I have recorded two videos to try to show the stages it does when going back to idle:
http://www.youtube.com/watch?v=RuSKmK4yP3Q
http://www.youtube.com/watch?v=nOQHAlUuQr0

If you could take a quick look?

[jonathanfenton]

Got p***ed off with reading wiring diagrams and bentley manuals haynes manuals and such like. Ordered a MAF from fleabay will post results. Took the car to pick up some tea and the power is defiantly back with vengeance its awesome forgotten how quick it was! Just need to sort out the hunting idle and the weird problem when coming off the throttle at about 2k revs. Stutters like it hasnt quiet got the mixture right. I have two options as i see it, MAF or Lamba sensor. It passes emitions tests with flying colours and the MAF currently on has done 143k miles and is 16 years old so i think it cant do it any harm to replace it!.... fingers crossed.

btw thanks for your documents crasher they are quiet revealing!

[jonathanfenton]

Didn't make a blind bit of difference but that old fault of signal too low intermittent on the throttle body and now the engine coolant temp sender has now started to flag up, looks like im going to have to see an auto electrician. yippie