Rough/noisy engine due too loose connection

[12Esc]

Hi,

I am the proud owner of a Tuscan for a couple of weeks now. Took some time to get it approved in the Netherlands, but since last week i am finally allowed to drive it. However, since it got back from MOT (APK), the engine sounded very noisy. Almost like a diesel engine. It took a very long time to get warm and even then still didn't sound ok (though better then cold).
After searching this forum, i expected the valves needed to be checked or something was wrong with the exhaust manifold. I recorded a movie to ask some opinions.
However: when recording the video i noticed a loose connection under the hood (exhaust side). It was one of two identical connectors. I reconnected it and started again and the engine sounded much smoother (although still cold so still some noise). After a short drive, the engine was warm and sounded very smooth (as it did when i collected the car).

So my conclusion is that the loose connection caused the engine to go lumpy. I have put together a video showing the engine before and after and showing the connection.

Can anyone tell me what the connection does? I followed it into a bundle of connections going near the engine on the inlet side (among which is temp sensor). Temperature and pressure were all displayed correctly on the dash.

Any input is welcome.

Movie here:
http://www.youtube.com/watch?v=ozEvzQiGV6w
(is is possible to embed movies here?)
The connection is shown at 1:04 and 1:26


Thanks,
Maurice.

Edited by 12Esc on Friday 7th May 10:27

[BGB autosport]

They are for the Lambda sensor which would explain the poor running. The wires go through that rubber bung round the chasis then out to the sensors in each of the manifolds just before the cats.

[12Esc]

ah, thanks.

[NCE 61]

They are the Lambda sensor connectors measure the oxygen content in the exhaust and input to the ECU to adjust the fueling, would have thorght this would give a error message on the display.

[Funky Jo]

You may want to get the diagnostics software and 3-PIN to Laptop connection cable in order to check the Lamda and adaptive mapping values. Gives a clear indication and avoids a lot of hours searching around in the engine bay...