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Discussion Starter #1 (Edited)
Hi I recently purchased a 2006 407 SW Sport, very high mileage (240k) but it's been looked after really well, with a master service in 2016 including additional work of new cam belt, water pump, fly wheel, clutch & head strip down, it's got a lot of the original service history too.

My problem is with acceleration, it's fine when I first drive it for about 10 minutes with loads of power when I accelerate, but as soon as the engine is up to normal operating temperature it gets really sluggish, when I'm in 4/5/6th gear it's pathetic & no good to overtake, it also takes a very long time to get up to 60/70mph

Any suggestions would be appreciated, I'm no mechanic but will attempt any work on a car I feel I can do to the best of my ability. I've checked the maf sensor by unplugging it & driving it but that didn't do anything. was wondering if it might be the egr blocked or possibly the dpf filter needing a clean?

I'm also considering if it's an issue with the turbo?

Thanks for reading
 

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Discussion Starter #3
240k is NOT hight miles :)

Your issue may simply be a loss of vacuum to the control system for the turbo no vacuum means no boost common issue on these engines.
Thanks for your reply, If that was the case why would it be running ok when cold? I'm also not sure it's got a turbo I can't find one under the hood but haven't had a look from underneath yet, I'm not sure if all these 2.0L HDI engines have a turbo I had a 307 HDI before this & it didn't have one
 

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Check the doser valves.as reliable says could be a vac leak.doser valve switches over to bypass intercooler when cold then switches back when engine is hot. Leak could occur on change over if diaphragm in unit is split

Sent from my SM-T310 using Tapatalk
 

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Discussion Starter #5 (Edited)
Check the doser valves.as reliable says could be a vac leak.doser valve switches over to bypass intercooler when cold then switches back when engine is hot. Leak could occur on change over if diaphragm in unit is split

Sent from my SM-T310 using Tapatalk
Ok thanks, just done a quick Google search into them & discovered that they look like a part I have noticed on the front of my engine, the part on mine looks like it is leaking oil but are they used for oil flow or just air flow? Will definitely be stripping them down now you have recommended that & the fact they look like they are leaking or have something close to them leaking oil too
 

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Oil is normal the oil is blown round the intercooler pipes and it leaks out any joints that are not perfect do not replace it for leaking oil as thats not a problem only replace it if the vacuum side is not working as it should.

Check all the small vacuum pipes under the bit you are talking about
 

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Discussion Starter #8
All seems ok but, questionable sensor connector?

Took it off & cleaned the maf sensor & all the internal piping, didn't touch the two round things on the outside I'm assuming they contain the diaphragms mentioned earlier, the butterfly valves seemed to be working ok, one was in the open position & one closed when I took it off, I'm assuming this is standard configuration? Had no difference in the cars power & after reading previous replies I think it is the turbo not kicking in, strange thing is it seems to be working when engine cold not just the engine alone as it accelerates very quickly in second & third.
Please see photos attached, I've found a sensor cable (blue connector) just hanging around near, can't find a sensor port anywhere to plug it in? Wondered if it was one for diagnostics or something as I'm sure I've seen a spare one underneath an old Pug I had before?
 

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Looking at their position tells you nothing and you are correct your turbo is not working

The main reason for turbo not working in this engine is LOSS OF VACUUM

Blue plug is for something your car does not have.

VACUUM
 

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Discussion Starter #10
Yeah I understand that now, but what I can't get my head around is why is the turbo seeming to be working when the engine is cold if it's a possible vacuum issue?

& thanks for clearing that sensor plug up for me it would have bugged the hell out of me lol
 

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There is no logic to faults like these could be your vacuum pump is weak and is only working properly when cold could be the pipework is only just sealing and when it warms up it leaks more who knows but its a simple enough system to check visually.

You need a vac gauge to test it fully but visual inspection usually finds the culprit bear in mind a leak in ANY vacuum pipe will affect the boost as they are all connected checking the turbo pipes are not enough but the turbo pipe going over the head is a common problem if yours has it there are various layouts.
 

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Discussion Starter #12
There is no logic to faults like these could be your vacuum pump is weak and is only working properly when cold could be the pipework is only just sealing and when it warms up it leaks more who knows but its a simple enough system to check visually.

You need a vac gauge to test it fully but visual inspection usually finds the culprit bear in mind a leak in ANY vacuum pipe will affect the boost as they are all connected checking the turbo pipes are not enough but the turbo pipe going over the head is a common problem if yours has it there are various layouts.
Thanks for all your advice, going to give it a thorough investigation today, will alos be looking at the egr seals/valve & if I can't find it I'll be putting it in a local garage later this week. Car drives lovely with the dual mass clutch & new fly wheel recently fitted just missing the acceleration, I do long distance journeys weekly & would love to have this car running correctly, currently it's frustrating on any journey knowing it should be performing so much more than it is
 

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join my facebook page Peugeot407 UK, well get you sorted without the need for a garage
 
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