Audi A3 2011 Technik 48K miles - Engine cut out, no codes
Discussion
Hi
At a loose end and desperate to work out what is wrong with my car.
It has been intermittently just cutting out, no juddering so I don't think its fuel related, mainly whilst stationary but on occasion whilst moving, always before it happens it feels sluggish and the revs seem low, its been into the garage x5 times including Audi, had both the RAC and AA out and no one can find or fix the problem.
Receiving no fault codes at the garages or with the breakdown agencies, I have a portable reader and no luck with that either.
One of the garages said, although I am now doubting they ever did, find a code suggesting the cam shaft sensor was the issue, this was replaced, broke down on the way home.
Just back out the same garage last week, spark plugs replaced, some acid residue found on the wiring, car seemed to run better but yet again its cut out.
Its worth mentioning the RAC advised I check the spark plug against metal when it happens again, I did and there was no spark so this was why I wanted the spark plugs looking at.
Every time it happens, it takes around 10-15 mins of failing to turn over and then starts again and I carry on my journey.
Annoyingly its never happened whilst the garage had it running.
Any help or advice, would be greatly greatly appreciated!
Thanks!
At a loose end and desperate to work out what is wrong with my car.
It has been intermittently just cutting out, no juddering so I don't think its fuel related, mainly whilst stationary but on occasion whilst moving, always before it happens it feels sluggish and the revs seem low, its been into the garage x5 times including Audi, had both the RAC and AA out and no one can find or fix the problem.
Receiving no fault codes at the garages or with the breakdown agencies, I have a portable reader and no luck with that either.
One of the garages said, although I am now doubting they ever did, find a code suggesting the cam shaft sensor was the issue, this was replaced, broke down on the way home.
Just back out the same garage last week, spark plugs replaced, some acid residue found on the wiring, car seemed to run better but yet again its cut out.
Its worth mentioning the RAC advised I check the spark plug against metal when it happens again, I did and there was no spark so this was why I wanted the spark plugs looking at.
Every time it happens, it takes around 10-15 mins of failing to turn over and then starts again and I carry on my journey.
Annoyingly its never happened whilst the garage had it running.
Any help or advice, would be greatly greatly appreciated!
Thanks!
Why on earth would you think it's a spark plug problem....when you're claiming the engine will not even turn over for 10-15 minutes ?
Clearly that aspect has nothing whatsoever to do with spark plugs.
And there are no other symptoms whatsoever, just an immediate dead stop ? Other than this, it runs perfectly ?
And with a proper scantool like VCDS or VAGCOM, when this problem occurs and scanning at that time before you turn the car off manually...there are no codes ?
Clearly that aspect has nothing whatsoever to do with spark plugs.
And there are no other symptoms whatsoever, just an immediate dead stop ? Other than this, it runs perfectly ?
And with a proper scantool like VCDS or VAGCOM, when this problem occurs and scanning at that time before you turn the car off manually...there are no codes ?
"Its worth mentioning the RAC advised I check the spark plug against metal when it happens again, I did and there was no spark so this was why I wanted the spark plugs looking at."
Just one or all of them?
If all of them, what is common to all....
Just one or all of them?
If all of them, what is common to all....
Edited by thetrickcyclist on Saturday 1st December 19:11
I would bet good money that the engine does turn over but doesn't fire, my reasoning being that checking for a spark at a spark plug can't be carried out unless the engine is cranking over
I enjoy banker bets although they do sometimes go against me
1000 Euros @ 1/2 odds on - Engine cranks but doesn't fire "Any higher bets" It's a banker you know it makes sense
I enjoy banker bets although they do sometimes go against me
1000 Euros @ 1/2 odds on - Engine cranks but doesn't fire "Any higher bets" It's a banker you know it makes sense
"Every time it happens, it takes around 10-15 mins of failing to turn over and then starts again and I carry on my journey"
This makes me think it's a fuel issue. Electrical issues don't usually show as trying and trying to start then it goes, fuel issues do.
Electrical issues would be more prone to throwing up codes, which again, you're not getting. Get fuel pressure checked, won't take a garage long.
This makes me think it's a fuel issue. Electrical issues don't usually show as trying and trying to start then it goes, fuel issues do.
Electrical issues would be more prone to throwing up codes, which again, you're not getting. Get fuel pressure checked, won't take a garage long.
Edited by robbocop33 on Saturday 1st December 12:52
robbocop33 said:
"Every time it happens, it takes around 10-15 mins of failing to turn over and then starts again and I carry on my journey"
This makes me think it's a fuel issue. Electrical issues don't usually show as trying and trying to start then it goes, fuel issues do.
How does a fuel issue stop the engine turning over?This makes me think it's a fuel issue. Electrical issues don't usually show as trying and trying to start then it goes, fuel issues do.
Mignon said:
How does a fuel issue stop the engine turning over?
By failing to turn over i read that as not firing up! So it's not cranking over at all then when it's not starting, so as someone says above, what exactly is it doing when trying to start it?Is there no noise whatsoever? Is there a clicking? Is there a grinding noise? Does the engine just move slightly?
Have you tried knocking the starter motor while turning the key? Are the lights dimming when you turn the key?
Think electrical feed to the starter is obviously intermitent, probably a bad earth somewhere, check battery earth cable, earth cables in general first.
stevieturbo said:
That would however make no sense whatsoever unless perhaps the person did not have a good grasp of English. Although they dont seem to appear to be a non native English speaker from the rest of their text.
Well i thought that if the car is running at times, then it must have turned over at some time,thought maybe he got his terms mixed up. Don't engines 'turn over' while they're running? Think they do. Sounds like a dodgy connection or possibly a bad earth if it’s failing to turn over.
If it was crank or cam sensor it would log an intermittent fault.
So if no faults logged in ecu its usually something mechanical.
Could easily be failing fuel pump or clogged fuel filter.
Intermittent faults are hard to find.
Good luck
If it was crank or cam sensor it would log an intermittent fault.
So if no faults logged in ecu its usually something mechanical.
Could easily be failing fuel pump or clogged fuel filter.
Intermittent faults are hard to find.
Good luck
Ach you lot make me smile. I think it's hugely unlikely to be low fuel pressure - ECU will show lean codes before stopping.
It's possible it's a crank sensor....... It's also worth looking on the BCU and ABS module for codes. Hopefully there will be something on there that says 'engine ECU not communicating' or similar.
But the big one for me is electrical supply to the engine ECU - failure here will result in no engine codes, and complete failure. So here's what I would do..... I offer this advice as an auto sparks who does this kind of rubbish every day, but with no liabilities.
1) Remove the ECU, and check power and grounds to the unit.
2) Put it back into it's little box with a lead from the power supply back to a voltmeter, or ideally an oscilloscope. Run it, drive it, when it cuts out, have a look to see if you have power to the ECU. If no, there's your problem.....
3) If yes, use the voltmeter to check 5v to anyone of the signals, and 12v to supplies such as the throttle body.
Given you have no sparks, it's probably going to be found in those 3 steps. Easy peasy lemon squeezy.
It's possible it's a crank sensor....... It's also worth looking on the BCU and ABS module for codes. Hopefully there will be something on there that says 'engine ECU not communicating' or similar.
But the big one for me is electrical supply to the engine ECU - failure here will result in no engine codes, and complete failure. So here's what I would do..... I offer this advice as an auto sparks who does this kind of rubbish every day, but with no liabilities.
1) Remove the ECU, and check power and grounds to the unit.
2) Put it back into it's little box with a lead from the power supply back to a voltmeter, or ideally an oscilloscope. Run it, drive it, when it cuts out, have a look to see if you have power to the ECU. If no, there's your problem.....
3) If yes, use the voltmeter to check 5v to anyone of the signals, and 12v to supplies such as the throttle body.
Given you have no sparks, it's probably going to be found in those 3 steps. Easy peasy lemon squeezy.
bearman68 said:
Ach you lot make me smile. I think it's hugely unlikely to be low fuel pressure - ECU will show lean codes before stopping.
It's possible it's a crank sensor....... It's also worth looking on the BCU and ABS module for codes. Hopefully there will be something on there that says 'engine ECU not communicating' or similar.
But the big one for me is electrical supply to the engine ECU - failure here will result in no engine codes, and complete failure. So here's what I would do..... I offer this advice as an auto sparks who does this kind of rubbish every day, but with no liabilities.
1) Remove the ECU, and check power and grounds to the unit.
2) Put it back into it's little box with a lead from the power supply back to a voltmeter, or ideally an oscilloscope. Run it, drive it, when it cuts out, have a look to see if you have power to the ECU. If no, there's your problem.....
3) If yes, use the voltmeter to check 5v to anyone of the signals, and 12v to supplies such as the throttle body.
Given you have no sparks, it's probably going to be found in those 3 steps. Easy peasy lemon squeezy.
Voltage supply issues to the engine ecu will absolutely leave fault codes on the ecu, codes result from even disconnecting the battery with the ignition off, never mind interruption of supply while the engine is running. It's possible it's a crank sensor....... It's also worth looking on the BCU and ABS module for codes. Hopefully there will be something on there that says 'engine ECU not communicating' or similar.
But the big one for me is electrical supply to the engine ECU - failure here will result in no engine codes, and complete failure. So here's what I would do..... I offer this advice as an auto sparks who does this kind of rubbish every day, but with no liabilities.
1) Remove the ECU, and check power and grounds to the unit.
2) Put it back into it's little box with a lead from the power supply back to a voltmeter, or ideally an oscilloscope. Run it, drive it, when it cuts out, have a look to see if you have power to the ECU. If no, there's your problem.....
3) If yes, use the voltmeter to check 5v to anyone of the signals, and 12v to supplies such as the throttle body.
Given you have no sparks, it's probably going to be found in those 3 steps. Easy peasy lemon squeezy.
Randon cutting out/failure to start while warm is classic crank sensor symptoms on these engines.
Warby80 said:
Voltage supply issues to the engine ecu will absolutely leave fault codes on the ecu, codes result from even disconnecting the battery with the ignition off, never mind interruption of supply while the engine is running.
Randon cutting out/failure to start while warm is classic crank sensor symptoms on these engines.
A more sensible train of thought.Randon cutting out/failure to start while warm is classic crank sensor symptoms on these engines.
But there is no crank sensor issue out there that would prevent the engine turning over. And it seems the OP isnt out there to give us any reliable information.
stevieturbo said:
Warby80 said:
Voltage supply issues to the engine ecu will absolutely leave fault codes on the ecu, codes result from even disconnecting the battery with the ignition off, never mind interruption of supply while the engine is running.
Randon cutting out/failure to start while warm is classic crank sensor symptoms on these engines.
A more sensible train of thought.Randon cutting out/failure to start while warm is classic crank sensor symptoms on these engines.
But there is no crank sensor issue out there that would prevent the engine turning over. And it seems the OP isnt out there to give us any reliable information.
For many with little to no interest in the mechanical function of their car, failing to start/failing to turn over are used pretty much interchangeably though.
Warby80 said:
Voltage supply issues to the engine ecu will absolutely leave fault codes on the ecu, codes result from even disconnecting the battery with the ignition off, never mind interruption of supply while the engine is running.
Randon cutting out/failure to start while warm is classic crank sensor symptoms on these engines.
Could be the crank sensor - already said that, but most modern engines will throw codes if you know how to look. (eg mismatch between cam and crank etc).Randon cutting out/failure to start while warm is classic crank sensor symptoms on these engines.
Otherwise low voltage will throw engine ECU fault codes, but NO voltage can't possibly do this, as the engine ECU is now isolated. Other units will flag no coms with engine ECU
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff