A3 1.6 BGU Loss of power on 2nd gear

[marci4]

Hi all,
Through a series of events I am now the owner of a 2004 A3 with 1.6 BGU under the bonnet. However I'm facing a bit of issues and don't really know where to look for the cause of them.. The biggest one is when I change into 2nd (no difference if it's an upshift from 1st or downshift) the engine loses the power. I can go full on the gas but the revs are somewhat stuck at about 2500-3000 and the car isn't accelerating. Once I press the clutch in and let go and then go on the gas pedal it goes back to normal and accelerates fine. It's also accelerating fine an all the other gears.

VCDS shows only one fault in the engine:
17947 - Clutch Pedal Switch (F36)
P1539 - 008 - Implausible Signal - Intermittent

I've read that this switch is used in Cruise Control to turn it off when you press the clutch, but my car doesn't even have that fitted so would that make a difference?

Anyone has any suggestions where to look for the source of issues?

 

[marci4]

I decided to replace the clutch switch, confirmed that it is working in Measurement Blocks in VCDS however car still behaves the same way... Very strange. This problem is so weird I don't even know where to start looking for the cause.

One thing is when I was looking through Measurement Blocks in VCDS I noticed there is a field which shows the currently selected gear. Mine shows 0 regardless of the currently selected gear. Could someone with A3 8P manual gearbox and VCDS check this if it is working for them?

 

[marci4]

Hello again,
So I haven't given up on wanting to fix my A3 - just a little shortage of time in the last time...
What I managed to do in the meantime:
- Changed battery (battery drain issue solved)
- Changed oil, oil filter, air filter and pollen filter
- Changed timing belt, tensioner and water pump (turns out at 114688miles it was still running on factory set )
- Changed thermostat which solved dropping temperature on motorway issue

Now as for the clutch sensor issue - I swapped the whole clutch pedal along with master cylinder and slave cylinder. Unfortunately still same issue.
BUT...
I noticed something extremely strange - the fault code shows a problem with F36 Clutch Pedal Switch. Looking at ELSA my car does not have such thing Clutch pedal sensor on my car is the G476 hall effect sensor that clips onto the master cylinder in engine bay. F36 is a switch which is installed just above the clutch pedal inside the cabin. Looking in there, there isn't even any mounting provision for such sensor so I'm completely confused.
Could this fault code be shown by ECU when there is any other fault that might be indirectly related to clutch sensor?
I have noticed the car is getting G28 (Crankshaft Speed Sensor) error from time to time. Sometimes it is fine and I can drive more than 160miles and nothing will come up, sometimes it's just a short trip into town and I get a light on dash, limp mode and the following fault code:

Crankshaft Position Sensor (G28)
Malfunction (P0335) Open Circuit/Short to Ground Intermittent

I tried cleaning the sensor, but that hasn't worked so I guess it'll have to be a new sensor then.

BTW. Can someone with 1.6BGU and FVH gearbox check the ECU coding to make sure mine is correct? Thanks!

Address 01: Engine Labels: 06A-906-033-BGU.lbl
Part No: 06A 906 033 DS
Component: SIMOS71 1.6l 2V 5559
Revision: --H03---
Coding: 0000071

Any ideas?

 

[piehole1983]

That coding is the same as mine. Looks ok.

Just a thought, have a look at your wheel speed sensors to what they're doing. Maybe one or more are picking up strange readings and causing the abs controller or ECU to cut power?

 

[piehole1983]

I decided to replace the clutch switch, confirmed that it is working in Measurement Blocks in VCDS however car still behaves the same way... Very strange. This problem is so weird I don't even know where to start looking for the cause.

One thing is when I was looking through Measurement Blocks in VCDS I noticed there is a field which shows the currently selected gear. Mine shows 0 regardless of the currently selected gear. Could someone with A3 8P manual gearbox and VCDS check this if it is working for them?

This one will probably be calculated from vehicle speed and engine speed and not an actual gear position sensor. The G28 fault might also be the cause of all this.

 

[marci4]

G28 sensor issue definitely got much worse now as the car goes to limp mode every time I drive it after around 10-15miles.
New sensor ordered and coming in on Tuesday so hopefully that will solve the issues.
Will update the thread once fitted

Also the loss of power when changing into 2nd problem is temporarily 'solved' by unplugging the G476 clutch position sensor in the engine bay. Interestingly no errors were flagged up relating to this sensor. Hopefully after replacing G28 I'll be able to plug this back in and the car will behave properly.

 

[marci4]

UPDATE: G28 Sensor replaced and all error codes in the engine went away immediately.
However the problem of power loss when going into second is still there... Any ideas? It is so bizarre it's still there without any error codes being flagged up. And it only happens when changing into second and it doesn't happen every time. Also I feel it happens less often now compared to before.

 

[mattss3]

Where did you get this car lol? Number plate doesn't start BF04 does it?

 

[marci4]

Haha long story mate And no, it starts with MA04

What's the story behind the BF04? ...I'm intrigued

 

[george_seamons]

Bit of a bump, and not sure if it is still relevant, but I have found a solution for this. Not sure if its sticky ground with regards to advertising or not though?!

Basically I have adapted my "Push Clutch To Start" Bypass Harness to irradiate this issue on the 1.6 cars. If anybody wants any more info, please feel free to PM me, don't want to get into trouble with the moderators!

 

[mdpol]

Hi. I haeve the same issue with my bgu 1.6 audi a3 . I have unpluged the clutch sensor for now thanks to this post... i have a usable car...my one limited the revs in 1,2, 3 gear.....it would to sort it out with your harnes hack....more info on this would be great.

 

[Chrissmith101]

My car has this same issue. Has anyone found a solution to it?

 

[Nicolae popa]

My car have the same problem 1.6 petrol (58) plate

 

[sam747]

Bit of a bump, and not sure if it is still relevant, but I have found a solution for this. Not sure if its sticky ground with regards to advertising or not though?!

Basically I have adapted my "Push Clutch To Start" Bypass Harness to irradiate this issue on the 1.6 cars. If anybody wants any more info, please feel free to PM me, don't want to get into trouble with the moderators!

hi, why you believe bypass push clutch resolve the no power issue in gears 1 & 2 ?

 

[raffter]

Hi all,
Through a series of events I am now the owner of a 2004 A3 with 1.6 BGU under the bonnet. However I'm facing a bit of issues and don't really know where to look for the cause of them.. The biggest one is when I change into 2nd (no difference if it's an upshift from 1st or downshift) the engine loses the power. I can go full on the gas but the revs are somewhat stuck at about 2500-3000 and the car isn't accelerating. Once I press the clutch in and let go and then go on the gas pedal it goes back to normal and accelerates fine. It's also accelerating fine an all the other gears.

VCDS shows only one fault in the engine:
17947 - Clutch Pedal Switch (F36)
P1539 - 008 - Implausible Signal - Intermittent

I've read that this switch is used in Cruise Control to turn it off when you press the clutch, but my car doesn't even have that fitted so would that make a difference?

Anyone has any suggestions where to look for the source of issues?

YO MEN DID U SOLVE THE F*** PROBLEM ? I HAVE THE SAME THING PLS TXT ME BACK

 

[vectrac20tsri]

Any real update on this? Got the same issue on a 2010 but this car requires the clutch to start so can not just leave it unplugged, If I unplug it while the engine is running then the issue has gone and no more limp / no power in 1st and 2nd.

We have replaced the clutch switch with one from a motor factors and no more code but still the same behaviour as above, has anyone tried replacing the switch with a genuine one?