Erratic throttle response when cold

[B@fink]

Enormously unlikely but since you have eliminated all the ignition/injection issues and you aren't getting fault codes and as it seems to occur on random corners/slopes have you considered the possibliity that there's a physical issue that's the cause? If some of the baffle stuffing or one of the catalysts are moving/loose it could act as a partial blockage cutting the power dramatically and as you turn/accelerate/release the throttle (or whatever restores the performance) it could then return to the correct position and it drives normally again. It isn't likely but not an impossibility and you might not have thought of it? Trying to think outside the box here I did have a car whose baffle stuffing started to come out that was intermittent on power before loosing it's go altogether which resolved my confusion to the power issues as the exhaust pipe had gained a dangly tail of stuffing out of it! new back box and it was back to normal. Hope all ideas are welcome.....even the slightly left field ones

[HPsauce]

Left field ideas welcome.
One of the cats was rattling when I bought the car, probably still is. Passed 2 MOT's since though.

[B@fink]

Perhaps It could still function correctly (I.e. Pass the emissions test) when not in the shifted (and blocking the exhaust) position, as long as the gas can get through the catalyst to react it will convert the gases still? Not sure how you could check it but stranger things have happened

[HPsauce]

I know it's only a few days, but the last time I experienced any oddness (low power, high revs at medium throttle) was about a week ago when I turned right at a T-junction on the A595 in Cumbria where it is joined by the A5093 at the coast near Silecroft.

After that I proceeded straight to the Hardknott pass which gave the gearbox a "good seeing to" on both 1 in 3 up and down slopes. During and since that journey it's felt fine. http://forum.a8parts.co.uk/showthread.php?t=8864

I wonder if there was some "redistribution" of fluid (or air bubbles or sludge?) as a result........

[Reffro]

Just a quick observation, your power issue seem recently to be joined with sharp turns. Is there something amiss with your power steering pump? I remember when on full lock in my old D2 it used to cause the revs to dip slightly.

Also with regards to rattling cats, that was definitely a cause of power drops in my car, at times it felt like it I had thrown out the anchor, as the material in one cat used to move and block my exhaust flow.

[ainarssems]

Could it be ESP sending torque reduction request to ECU as this seems to happen on hills and turns maybe roll, yaw or acceleration sensors inside ESP unit are not reading quite right always. poor connection, dry solder joint maybe.

[HPsauce]

Yes, it's definitely associated with sharper turns, though not hard ones as it's usually at low speeds so minimal lateral forces.

I think the acceleration and yaw sensors are under the drivers seat so maybe I'll try to find and re-plug those. The yaw sensor sounds more relevant.

But the condition 100% clears with a twitch of the throttle (lift off and reapply) so I'm dubious, unless that somehow makes the relevant ECU have a rethink?

If it was readily reproducible I could try with ESP off and see if that changed things, but it's not predictable enough.

[PsYcHe]

Maybe the steering angle sensor as well, giving incorrect readings, so causing the car to think that there's a slide on..

Do you get the ESP light flashing when it does it? That would maybe point it more to the cat/PS pump if not.

[HPsauce]

Definitely NEVER seen any ESP light when this happens.

[HPsauce]

Originally Posted by HPsauce

the last time I experienced any oddness (low power, high revs at medium throttle) was about a week ago ...........
After that I proceeded straight to the Hardknott pass which gave the gearbox a "good seeing to" on both 1 in 3 up and down slopes. During and since that journey it's felt fine.

And is still fine after nearly 3 weeks.