2008 Audi a3 jerking when releasing or pressing gas pedal

Deki06

Deki06

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Hi everyone, thanks for any help.

Car is audi a3 8pa 2008. with 1.6 BSE petrol engine 135000km.

Long story short, car sometimes jerks noticably when pressing or releasing gas pedal, doesnt matter how slow or fast. It started 2 weeks ago when driving steap uphill with loaded car. Now it doesnt matter if its flat or hilly, hot or cold, 1 day it jerks a bunch (like in a video), other days jerks a little only when pressing gas pedal but stil more than it should, and some days it drives totaly fine. Only solution i found that helps a bit while driving, if its jerking very hard, to drive it in 2nd gear to 5, 5.5 000 rpm for a 2,3 seconds, and than it gets better.

This car has some problems dating 2y ago when i bought it, basicly sometimes it shakes at idle but rpm is constant and no codes. We changed spark plugs, coils, coil wires, cleaned fuel injectors, replaced timing belt, water pump and battery. Nobody realy knows what is causing shaking, but now this is more serious problem.

Any tips would be very helpful.


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It could be the accelerator potentiometer/rheostat showing signs of excess wear, if it's a 'drive by wire' type?

Does the pedal have electrical wires, or a mechanical bowden cable coming out of it?
 
I'd be amazed if it's not fly by wire, my old 2000 Passat was FBW. Any way of testing to check if it's worn? Without replacing it obviously!

I was thinking it could also be the DMF failing/failed?
 
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MrHockin said:
I'd be amazed if it's not fly by wire, my old 2000 Passat was FBW. Any way of testing to check if it's worn? Without replacing it obviously!

I was thinking it could also be the DMF failing/failed?
Click to expand...

I would test it with a mutimeter, on the resistance range, across the unplugged terminals of the pedal. As the pedal is moved, there should be a smooth variation in resistance.
 
I believe your car has an ignition control module.
Test that if you can or just get one from a scrappy for a tenner or so.
Worth a punt if everything else failed.
 
Codes where scanned with vcds, im thinking od recording sensor outputs with vcds while driving for throtle position sensor and throttle body sensor, but its hard because it happens so randomly and i cant replicate the issue when i want it. Also car has only map sensor, no maf, and its not drive by wire. Im leaning thowards the ignition or fuel issue because one day i had no start condition, for half an hour, also no codes. Engine would spin 2 turns, turn on for like 1ms and shut down immediately
 
Might be worth checking/cleaning your MAP sensor in the first instance then, following that it's a case of fingers crossed with no codes. I'd likely go with fuel pump afterwards, but obviously can't say for sure especially if it's sporadic, literally the worst issue to have! Good luck
 
Deki06 said:
Codes where scanned with vcds, im thinking od recording sensor outputs with vcds while driving for throtle position sensor and throttle body sensor, but its hard because it happens so randomly and i cant replicate the issue when i want it. Also car has only map sensor, no maf, and its not drive by wire. Im leaning thowards the ignition or fuel issue because one day i had no start condition, for half an hour, also no codes. Engine would spin 2 turns, turn on for like 1ms and shut down immediately
Click to expand...
Sounds like fuel supply
 
Only solution i found that helps a bit while driving, if its jerking very hard, to drive it in 2nd gear to 5, 5.5 000 rpm for a 2,3 seconds, and than it gets better.


That sounds like not enough fuel at lower revs.
 
Could it be something to do with the gas conversion, how does to would with petrol? Is there a different pedal for gas and petrol? I was apprenticed as a motor vehicle and bridge technician, today it seems all my training has gone, how to set up a carburettor etc. The only way is to connect to a computer of some sort and see what it tells you.

I did move sidewards and worked on PLC's etc, Main tool was the laptop, but it still needed some knowledge to work out what the laptop is telling you. I moved into heavy industry i.e. people willing to pay me a good wage, the problem with any job connected to general public is people are not willing to pay for expertise.

But you have a fault which is unlikely to be cured by the take a guess and replace a part process, you need to get some one with a computer type machine to see what the engine management is telling them. I have to take my car to a garage, no way can I afford the equipment needed to work out what is wrong.

DIY with cars is only for vintage and veteran cars.
 
ericmark said:
Could it be something to do with the gas conversion, how does to would with petrol? Is there a different pedal for gas and petrol? I was apprenticed as a motor vehicle and bridge technician, today it seems all my training has gone, how to set up a carburettor etc. The only way is to connect to a computer of some sort and see what it tells you.

I did move sidewards and worked on PLC's etc, Main tool was the laptop, but it still needed some knowledge to work out what the laptop is telling you. I moved into heavy industry i.e. people willing to pay me a good wage, the problem with any job connected to general public is people are not willing to pay for expertise.

But you have a fault which is unlikely to be cured by the take a guess and replace a part process, you need to get some one with a computer type machine to see what the engine management is telling them. I have to take my car to a garage, no way can I afford the equipment needed to work out what is wrong.

DIY with cars is only for vintage and veteran cars.
Click to expand...
The car has been plugged into a computer for diagnostics, there are zero codes given hence the advice given so far.
 
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