Audi S6 AAN engine speed sensor problem

[bn-01-wso]

Hello everybody. I've bought an Audi S6 a few weeks ago and its beginnig to give me headakes already. It ran fine until a few days ago. When its beginning to warm up it reaches 4000 - 5000 rpm flat out and then it would not rev any higher. If i go gentle with the throtle it would rev higher but in shocks, not a constant acceleration and not as fast as it used to be. I changed the coils with TFSI ones but same problem. The only engine fault after diagnose is the engine speed sensor it sais signal interrupted or something like that. The diagnose was carried out using both Bosch ESI tronic and a gutman tester. Same error. So i changed the g28, ran fine for a day and then same problems. Changed it again, same thing. What else can cause this? A wiring problem or something? I forgot to mention it starts fine in both warm and cold conditions, and revs fine up to 4000 - 5000. Any info will be apreciated. Thanks a lot

[rynaqui]

Hello everybody. I've bought an Audi S6 a few weeks ago and its beginnig to give me headakes already. It ran fine until a few days ago. When its beginning to warm up it reaches 4000 - 5000 rpm flat out and then it would not rev any higher. If i go gentle with the throtle it would rev higher but in shocks, not a constant acceleration and not as fast as it used to be. I changed the coils with TFSI ones but same problem. The only engine fault after diagnose is the engine speed sensor it sais signal interrupted or something like that. So i changed it, ran fine for a day and then same problems. Changed it again, same thing. What else can cause this? A wiring problem or something? I forgot to mention it starts fine in both warm and cold conditions, and revs fine up to 4000 - 5000. Any info will be apreciated. Thanks a lot

I believe engine speed sensor (G28) will always show when the engine is not running so it is not the fault you are looking for.

If you are experiencing misfires, you could also check the condition of your spark plugs. Also is it smoking? Can you post a video of how the car is running such as sound it's making (enginebay), video of the speedo with sound (WOT and less throttle) and or boost gauge. It can help people identify with the problem more and give you a more accurate diagnosis

[bn-01-wso]

Engine starts and drives fine until 4-5k rpm. I changed the spark plugs also, brand new F5DPORs were fitted. No missfires. Thanks a lot

[bn-01-wso]

Also change the N75 valve, same thing. I dont have a boost gauge for now. It doesnt smoke. thanks

[quattro-nick]

check your fuelpressure or maybe switch your MAF with another one!
you also can check the distance between the g28 sensor and flywheel but normaly this sensor is used for rpm gauge so i dont think this can be your problem

[UrS4boy]

One missing and hesitation diagnostic

.... Any info will be apreciated. Thanks a lot

As state, the G28 Engine Speed Sensor fault code *ALWAYS* shows up if you pull the codes on an engine that isn't running.

Have a read on the Missing and Hesitation Diagnostic info in this post:

http://forums.quattroworld.com/s4s6/msgs/22611.phtml

[bn-01-wso]

Thanks a lot for the info. I put some videos on youtube. All videos are at full throtle. i will try to change the fuel pump today and see what happens.

http://www.youtube.com/watch?v=NBL108DZ_IQ

http://www.youtube.com/watch?v=NrHdi67Wqy8

http://www.youtube.com/watch?v=saO8JFFBTFc

[rynaqui]

Could be a fuel related issue? Maybe someone else on here can shed some advice based on the videos

[quattro-nick]

i think you must look at the fuel regulation (air or fuel)
you can check:-fuelpressure
-boostpressure
-bad MAF
-coolendtempsensor
-blocked air filter
-blocked exhaustCAT

most of those things you can check with a diagnostic tool in measurement blocks like vagcom or so

[pasbogdan]

Fuel pressure test,with engine/car running full throttle to rev limit.

[bn-01-wso]

problem solved. Bad fuel pump. Puls like a train once again. Thanks a lot.

[quattro-nick]

[rynaqui]

Awesome, nice simple solution

[bn-01-wso]

It wasnt the original fuel pump. It was also replaced by the previous owner. Same Bosch fuel pump like i've bought. Seems like they have a short life. I hope mine will live litle bit more :-P