Rough idle and running EPC and missfire - AudiForums.com


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Old 07-12-2016, 11:54 AM
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Default Rough idle and running EPC and missfire

Hi everyone


2009 Audi A3 Quattro 2.0T


issue start a month ago EPC light on and off turn off the car wait a minute and car is driving again no light everything is good.


search a little about the EPC found out it might be the throttle body remove the TB the other day was pretty dirty clean it and put it back on. drive the car for 3 days and no EPC light come on again. The other day coming back from work and the check engine light is on again and car running very rough could not accelerate at all, car is shaking every time you press the gas pedal.
check the error code with my VAG-com and got misfire on cyl. 1 and cyl number 1 is disabled. pull all plugs out, it look like im running reach on 1 and 3 and running lean on 2 and 4, hook up my compression tester and check all cyl. all show above 175. Clear all code and start the car again, this time check again light is flashing and car idle very rough when I give it some gas the check engine light stop flash and is off, put it to gear check engine light is flashing again after a few minutes EPC light is on and check engine light is off car is running very rough and can barley accelerate.


just want some ideas before going and buying a new throttle body and spent another $$$$ on repair.


Thanks

Last edited by EZaudi; 07-14-2016 at 04:56 PM.
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Old 07-14-2016, 04:58 PM
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204 Viewer no one has a comment ??? suggestion ? anything to try ?? or should I say goodbye to $340 for new T.body
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Old 07-15-2016, 12:02 PM
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It's a tough one and I'm sure most viewers rather not give wrong advice. I'm in the same boat and not entirely sure what to recommend but I wouldn't be looking at the throttle body right away. The throttle body regulates intake air and therefore should affect all cylinders equally not just a single one.
Seeing that it affects mostly number 1 - have you tried to swap the coilpack with another one and see if the issue follows that coil pack? If so you found the issue and can simply replace the coil packs (and sparks plugs while you are at it).
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Old 07-15-2016, 12:35 PM
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Quote:
Originally Posted by sheldon View Post
It's a tough one and I'm sure most viewers rather not give wrong advice. I'm in the same boat and not entirely sure what to recommend but I wouldn't be looking at the throttle body right away. The throttle body regulates intake air and therefore should affect all cylinders equally not just a single one.
Seeing that it affects mostly number 1 - have you tried to swap the coilpack with another one and see if the issue follows that coil pack? If so you found the issue and can simply replace the coil packs (and sparks plugs while you are at it).
I guess you right but I really ran out of ideas of what wrong with it.
I did swap the coil and new plugs still misfire on number 1. but it use to run fine even with the misfire until a week ago when it decided no more.


im thinking the throttle body will fix the issue of the rough idle and acceleration the misfire I believe it maybe something with the wiring is it possible to move the ignition wiring to a different cyl. ??


Thanks I do appreciate your respond
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Old 07-15-2016, 05:18 PM
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I would not move the wiring as the computer tells it when to fire. If you move it it will be out of sequence. When the computer wants to fire cylinder 1 and the wiring is moved to 2 for example it will make things worse. You could try to move the injectors around but you have to seal them properly or you will get other problems.
Another common issue next to the TB is the MAF sensor, however again I see this affecting more all cylinders and not just a single one.

Have you ever looked into valve cleaning? I've read that our cars have a horrible reputation of building up carbon on the valves which in return causes misfires, rough idling, poor gas mileage, etc.
Just google it and be amazed how how many have this issue and have many things it can affect:
Let me google that for you

Last edited by sheldon; 07-15-2016 at 05:23 PM. Reason: added advice about injectors.
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Old 07-18-2016, 10:33 AM
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Quote:
Originally Posted by sheldon View Post
I would not move the wiring as the computer tells it when to fire. If you move it it will be out of sequence. When the computer wants to fire cylinder 1 and the wiring is moved to 2 for example it will make things worse. You could try to move the injectors around but you have to seal them properly or you will get other problems.
Another common issue next to the TB is the MAF sensor, however again I see this affecting more all cylinders and not just a single one.

Have you ever looked into valve cleaning? I've read that our cars have a horrible reputation of building up carbon on the valves which in return causes misfires, rough idling, poor gas mileage, etc.
Just google it and be amazed how how many have this issue and have many things it can affect:
Let me google that for you
Thanks for the Video I bet my engine has a lot of build up with the miles im running on it 178K I will remove the intake and see what I found, I clean the MAF sensor a month ago, nothing change, but back then I did not have any rough idle or any problem with acceleration. when I took the TB out to clean it I found another sensor that was completely black and it is connected to the intake above the TB what is that sensor do ? maybe my whole problem is that sensor and nothing else, I connected my computer this weekend to the car and run a vag test on the TB and it returning ok value do you know of any other test I can run using the ross-tech software that can tell me a little more ?


Thanks
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Old 07-18-2016, 09:36 PM
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If you show me a picture of that sensor and it's location I could probably tell you what it is but the 2009+ (or TSI) engines are different than the FSI engines so I don't know exactly what is where in your engine bay - though probably very similar still.
I have the Ross Tech cable as well but have no clue how to use it properly besides reading out codes and re-coding stuff. So, unfortunately I won't be any help in that area.

At this point since only cyl.1 is having issues I would isolate my search to things that can affect the cylinder and not the entire engine. You checked compression - that's a big thing off the list. You checked spark plugs and coil packs so that's 2 down. Now I would look at injectors and the valve cleaning next if it were me.
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Old 07-20-2016, 09:59 AM
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Quote:
Originally Posted by sheldon View Post
If you show me a picture of that sensor and it's location I could probably tell you what it is but the 2009+ (or TSI) engines are different than the FSI engines so I don't know exactly what is where in your engine bay - though probably very similar still.
I have the Ross Tech cable as well but have no clue how to use it properly besides reading out codes and re-coding stuff. So, unfortunately I won't be any help in that area.

At this point since only cyl.1 is having issues I would isolate my search to things that can affect the cylinder and not the entire engine. You checked compression - that's a big thing off the list. You checked spark plugs and coil packs so that's 2 down. Now I would look at injectors and the valve cleaning next if it were me.


here is a picture hope you can tell me what is it
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Rough idle and running EPC and missfire-img_8987.jpg  
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Old 07-20-2016, 10:19 AM
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That looks like the intake air temperature sensor - if bad it could certainly explain the running rich/lean condition. I doubt however it would affect a single cylinder misfiring.
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Old 07-20-2016, 10:33 AM
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Quote:
Originally Posted by sheldon View Post
That looks like the intake air temperature sensor - if bad it could certainly explain the running rich/lean condition. I doubt however it would affect a single cylinder misfiring.


do you think it will have any effect on the rough idle and acceleration ? I can get one of these it only $15 not bad for Audi I thought there is no parts under $100


If I will have time today I will remove the intake and see how it look. just want to say Ty for all your help and ideas I greatly appreciate it.
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