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      07-05-2011, 01:59 PM   #1
9InchPianist
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Question Intermittent power loss & sluggish throttle response

Evening all!

It's been a while since I've frequented the boards (probably not since I had my E91 3 er actually!).

Anyway, straight down to business...

In the 6 months that I've had my '56 plate (Dec 2006) E85 2.5si Roadster, I've had probably no more than 6 instances of this problem which the dealer so far is unable to resolve as no faults seem to be logged, no warning lights on the dash etc...

The symptoms are as follows:

Whilst driving along there will be a slight jerk (which is more noticeable if I'm accelerating at the time) after which there is a noticeable lack of power and the throttle response becomes incredibly sloppy.

If I 'blip' the throttle at idle, the car hesitantly raises and lowers the RPM.

If I turn off the ignitiion and back on again, all is well again until the next time it randomly decides to do it again, at which point it's CTRL + ALT + DELETE time again

I've booked my car back in to Stratstone in Derby but suspect that they won't be able to find fault again.

Looking for any inspiration / thoughts as to what might be wrong - the fault doesn't really annoy me too much it's just a bit irritating and I'm worried that it may be a sign of something more fundamentally wrong.

9IP.

I've now managed to capture some video of the problem, either scroll down this thread to view or click here.
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Last edited by 9InchPianist; 07-11-2011 at 02:51 PM.
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      07-07-2011, 12:25 PM   #2
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Quote:
Originally Posted by 9InchPianist View Post
Evening all!

It's been a while since I've frequented the boards (probably not since I had my E91 3 er actually!).

Anyway, straight down to business...

In the 6 months that I've had my '56 plate (Dec 2006) E85 2.5si Roadster, I've had probably no more than 6 instances of this problem which the dealer so far is unable to resolve as no faults seem to be logged, no warning lights on the dash etc...

The symptoms are as follows:

Whilst driving along there will be a slight jerk (which is more noticeable if I'm accelerating at the time) after which there is a noticeable lack of power and the throttle response becomes incredibly sloppy.

If I 'blip' the throttle at idle, the car hesitantly raises and lowers the RPM.

If I turn off the ignitiion and back on again, all is well again until the next time it randomly decides to do it again, at which point it's CTRL + ALT + DELETE time again

I've booked my car back in to Stratstone in Derby but suspect that they won't be able to find fault again.

Looking for any inspiration / thoughts as to what might be wrong - the fault doesn't really annoy me too much it's just a bit irritating and I'm worried that it may be a sign of something more fundamentally wrong.

9IP.

Valvetronic actuator motor or faulty gas pedal. Any codes?
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      07-07-2011, 12:53 PM   #3
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No codes, no lights.

Zip zilch zero.

I'll see if the dealer reports any this time around - it's going in on the 29th of this month.
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      07-07-2011, 05:17 PM   #4
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Try a fuel system cleaner. I got bad fuel one time with my 3.0i, and it had similar symptoms to what you listed but a little more extreme. The fuel system cleaner took care of it with zero recurrences.
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      07-11-2011, 02:49 PM   #5
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Managed to get some video of it tonight:

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      07-11-2011, 03:00 PM   #6
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      07-12-2011, 07:48 AM   #7
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Well since the car isn't going in until th 29th I might as well try the fuel system cleaner.

Just got back from Halfords and bought myself a bottle of Wynn's Forumla Gold High Performance Petrol System Treatment

I'll swing past the Shell Garage on the way home and fill up again, then plop this in the tank.

Be nice if it was as simple as this!

With regard to vanos vs. variable valve timing, it's my understanding that these are two completely different (yet related) things, which begs the question, which would you say is the most likely culprit based on the video evidence and the fact that the car has only done 34,000 miles?

I thought that this was probably unrelated but I also seem to get a noticeable amount of 'knock' (pinking / pinging) at low RPM under load (e.g. accelerating uphill).

Thanks for your suggestions thus far!
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      07-29-2011, 03:31 AM   #8
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Well the fuel system cleaner has certainly reduced the knock, but hasn't made any difference to the main problem.

See what the dealer can find today.
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      07-29-2011, 12:15 PM   #9
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Quote:
Originally Posted by Z4-Villalona View Post
vanos
Just got mi motor back.

Things are looking promising, this time around as there were some fault codes logged (I don't have the exact codes) that led them to the Exhaust Vanos Solenoid.

So for now it has been flushed, and if the fault re-occurs they said they will replace the solenoid.

I can honestly say the car feels different since the flush, it seems to idle even more smoothly, throttle response seems 'sharper' with sport mode on, and 'smoother' with it off.

So things are looking up, time will tell though!
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