Engine Hesitation - TSB

[Cheese]

2021227/2
Powertrain / Function / Engine problems while driving
Powertrain / Function / Driveability (engine)
Powertrain / Function / Lack of performance
01 Light engine hesitation under acceleration at steady throttle application at 2500 rpm and 3800 rpm

Interesting reading in light of some of the issues reported by myself, Brett Butler and Paddy recently. Can't find a copy of the TSB though to see if it applies to A3s as well:
Hesitation under light acceleration - A5_OC
[URL]http://www.a5oc.com/forums/a5-general-q/9885-turbo-issue-2-0-a.html[/URL]

 

[paddy]

Interesting stuff Cheese.
I traced my problem to plugs. I took the std plugs out at 4k miles and put a mega tester on them. Checking for a leak to earth at 500v two were fine and came up as infinity and to had a leak of 400m ohms. Basically a leak to earth that would have got worse under load and compression. One plug failure at 4k is bad luck, two is a pointer to a fault in the plugs or their unsuitability for the engine.
I note the Yanks in the link above are having problems across the range from 2.0T to 3.2 and so its going to be something common across engines.
My thinking is we are mislead a lot of the time because a minor fault can shut down the system momentarily. I know for a fact that one injector failure can cut power to the other 3 to save engine damage or a pollution disaster . so it seems possible that a bad plug could cause the system to momentarily shut down causing a small misfire to become a ignition cut/jerk on the road.
I can only guess but i think the problems are very small but amplified by the Canbus system under stupid rules that might, god forbid, allow a hydro carbon to escape !!!!

 

[Cheese]

It is good that you have the equipment to test them and know for sure they were faulty. In my case I think the spark plugs were 90% of the problem but there is still something not quite right. I still occasionally get a little bit of a hesitation at peak torque and jerking with a heavily loaded car, especially uphill and if the engine has not warmed up.

Below 2,500rpm the car does not feel smooth like it used to and this is worse when it is cold. A few times when cold the engine has taken three to four times longer trying to turn it over before it started. According to AmD Audi are aware of some injector issues with my age and model of car so may be it is that. Maybe the colder spark plugs just don;t operate as well under normal driving conditions as the are closer to 'race spec' plugs and just like it when the revs are up...

 

[paddy]

I do wonder if you sorted one problem with a good set of plugs but started another by going with the cooler range. I appreciate your engine mods but unless you are using that potential performance regularly on the road then you might still be better off with std plugs for everyday driving with the occasional spot of boot to the floor fun.

 

[Cheese]

Exactly what I was thinking. I will drop AmD an email and ask about it.