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DSK

Performance/Boost Issue

13 posts in this topic

My car has been running sweet or several weeks after Tim worked his usual magic. 

 

However, in the last 2 weeks, I noticed that upon acceleration, part/full throttle, the car would be instantly responsive and do what my right foot instructed but, within a second or so it would then slightly hold back and stay there, almost like giving you 15% less than what you requested and it initially gave.  Almost feeling like something intervening and cutting back some fuel or ignition but still being very smooth.  Whereas it always felt like the accelerator had a bubbling volcano underneath it, always ready and eager to deliver, its does feel as though something is restricting the performance, having to press harder than I should.

 

Initially the problem wasn't enough to bother me or Tim as I felt it may be like looking for a needle in a hay stack.  However, today I noticed a little less smooth idle on the odd occasion and saw the boost gauge fluctuating when in neutral or park and the car is at idle.

 

(VIDEO) This is how the gauge usually sits on idle

 

http://vid669.photobucket.com/albums/vv60/dskandola/Volvo%20C70%20T5%20GT/DSCF0546_zpskfwq24m6.mp4

 

(VIDEO) Current fluctuation at idle

 

http://vid669.photobucket.com/albums/vv60/dskandola/Volvo%20C70%20T5%20GT/A68E013D-037D-4AA8-B5C8-B83D4C72D9C9_zpstxh0juo1.mp4

 

Any ideas if its something any idiot can check before I can get a booking with our residential guru?

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ADDITIONAL INFORMATION

Over the past few weeks, the issue has been getting worse and more things I have noticed.

1.  Fuel Consumption is down by approximately 10mpg under the same driving conditions.

2. Whilst crusing at a steady speed on the motorway 70/75mph with and without cruise control on, the car sometimes hestitates quite noticeably and is then OK again.  Feels like a sudden momentary fuel shut off, rather than a misfire.  Sometimes when it recovers it either feels like you have to press on a bit to retain the speed or it reverts to it's amazing self of feeling like you need the lightest of touch on the throttle to cruise effortlessly at whatever pace takes your fancy.

The car has had a new genuine Bosch MAF fitted by Tim so can't be that surely.  The car has not thrown an EML light at all.  The fuel filter was replaced with an OEM item during routine servicing 20,000 miles ago.  A new OEM fuel filter will be fitted at the next service when Tim can fit me in.

I am suspecting vacuum/boost hose related issue or 02 sensor - does this sound like I'm along the right lines?

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Oooh that's a lump idle.  Which car is it? If ME7 perhaps a VVT issue?

I would check for air leaks all the way from the MAF to the cylinder head including recirc, servo and TCV vac lines, I have had a leak on the compressor inlet pipe before causing similar results.  Checking fuel trim can give an indication that something is wrong.

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S40RCH - thanks for the response.

The car is a ME7, genuine 90,000 miles now, regularly serviced all its life with a recent clean bill of health from guru Tim Williams.  (I have changed the VVT on my other ME7) but this feels more like a fuelling/vacuum leak issue.  I will try to have a look tomorrow morning in day light at the hoses and try and work my way through them but, when there has been an issue with them, I've never noticed it, just felt it and Tim's magic hands instantly find the issue.  But, I'll give it a go!

Also ordered a phone app based OBD2 thingy to try and see if I can get some fuel trim/02 and maf values over the coming days which should help you guys tell me if I need to order any parts. 

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STATUS : BETTER

I popped the bonnet and had a look around.  All hoses are connected and still appear to be in sound condition.

The 3 hoses that come out of the TCV Solenoid, only 1 was in its place holder.  So I clipped the other 2 into their plastic clip holder things just under the TCV.  These still retain their shape and I saw no kinks or questionable bends in any of the hoses.

The car is now much stronger on part throttle and MPG was showing 36mph rather than 29mpg for the routine identical motorway jaunt I do weekly.  The car is also just cruising and accelerating on the very lightest of throttle inputs whereas before I was having to 'press on' to retain speed and making usual speed adjustments.

I fail to see how just clipping the 2 hoses back into place could have such impact as their routing/shape/location wasn't changed. I can only guess if general dirivng conditions when pressured, caused them to move and thus was resulting in the impact but, they felt sturdy none the less.

I will keep an eye on the idle this evening and try and get some diagnostics on Wednesday when I take a different route.

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4 hours ago, DSK said:

I fail to see how just clipping the 2 hoses back into place could have such impact as their routing/shape/location wasn't changed. I can only guess if general dirivng conditions when pressured, caused them to move and thus was resulting in the impact but, they felt sturdy none the less.

 

If the only thing you did to resolve the issue was move the TCV hoses then I would suggest removing them all and inspecting them properly for splits.  Then place them in the bin and replace with fresh, it should cost you a couple of quid for a metre or 2 of gates 4mm hose and some p clips.  Whilst doing it I would recommend replacing the TCV and recirc valve hose too.

Ryan

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4 hours ago, DSK said:

I fail to see how just clipping the 2 hoses back into place could have such impact as their routing/shape/location wasn't changed. I can only guess if general dirivng conditions when pressured, caused them to move and thus was resulting in the impact but, they felt sturdy none the less.

 

If the only thing you did to resolve the issue was move the TCV hoses then I would suggest removing them all and inspecting them properly for splits.  Then place them in the bin and replace with fresh, it should cost you a couple of quid for a metre or 2 of gates 4mm hose and some p clips.  Whilst doing it I would recommend replacing the TCV and recirc valve hose too.

Ryan

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Thanks Ryan

If it runs like this until it's next visit to Tim as soon as he can fit me in, I'll let him do it but I'd like to change those hoses as a matter of course anyway.

IIRC I thought the upgrade was 10mm reinforced fuel hose? I'm sure that's what was done on the S70R done.


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Nope 4 or 5mm fuel hose. Just make sure you replace the hoses one by one so that you get them on the right TCV ports. It should take about an hour on a cold engine.


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Thanks Ryan

Tim fitted the gates hoses and after a service took it for a spin and worked his magic with diagnostics. Turns out the issue is with the ETM.

Saw your car there too looks lovely!!


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On ‎22‎/‎04‎/‎2017 at 8:48 PM, DSK said:

Thanks Ryan

Tim fitted the gates hoses and after a service took it for a spin and worked his magic with diagnostics. Turns out the issue is with the ETM.

Saw your car there too looks lovely!!


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Sounds like he's cleaned it then! :lolbang:

Yours all sorted?

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I didn't realise the spec you were running! Very impressive.

I just need to go back for a new ETM, will have to leave the pesky 2.0/3.0ltr diesel Germans alone until then.


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The car has always gone very well for what it is, I think mainly as I have kept on top of any issues until an oil leak came too much at 209k so I decided it was time for Tim to drop one of his special build's in.  Hopefully getting it back this month, less than 2 weeks until the ring!:whistling:

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