Peugeot 407 2.0 HDi Flat spot? - Hughm
I'm really pleased with my 55 plated Peugeot 407 2.0 HDi SE saloon - it's quick and quiet and a great deal of car for the money. It even accelerates in 6th!

I paid less than £10K for a 12K mile example from Robins & Day. It was a Peugeot owned car.

However, spirited driving reveals a really annoying flat spot when engaging the next gear (i.e. 1st to 2nd) and the revs are about 1500. No power. Then, half a second later it's there (just) but it happens in every 'next' gear, every change to a higher gear.

Is it simply my driving style? Do I need to learn how to drive modern turbo-charged diesels or is there a problem with this model and its ECU mapping? Or is it just my car?

I have yet to confront the Peugeot dealer - that will be my next course of action but in the meantime - does anyone else have this problem?

An Internet search for '407 flat spot' only shows one thread in an Asian forum ...

I look forward to your comments and ideas - I had a great deal of help with a Civic steering problem acouple of years ago ....

Knd Regards

Hugh Milsom
Peugeot 407 2.0 HDi Flat spot? - Lud
It does sound like yr driving style Hm... try changing up at slightly higher revs so that the next gear comes in at around 2,000.
Peugeot 407 2.0 HDi Flat spot? - LeePower
Take it to your Peugeot dealer, they will have seen 1 or 2 ( well lots ) of 407 HDI's with this problem.

Pretty sure there's been a TSB on this issue & a modification to one of the parts in the throttle butterfly as well.

Its under warranty so let Peugeot U.K. / PSA pick up the bill.
Peugeot 407 2.0 HDi Flat spot? - Hughm
Do you by any chance have a copy of that TSB?

Kind Regards

Hugh Milsom
Peugeot 407 2.0 HDi Flat spot? - LeePower
Sorry no, It was passed on to me by a Pug technician.
Peugeot 407 2.0 HDi Flat spot? - mss1tw
Pretty sure there's been a TSB on this issue & a
modification to one of the parts in the throttle butterfly as
well.


On a diesel?!
Peugeot 407 2.0 HDi Flat spot? - Screwloose
On a diesel?!


Yup; been on the commercials for years. 'Think that PSA call it a dozer valve; it's ECU vacuum controlled and covers both EGR and FAP regen functions.

Well prone to sticking and linkage issues too.
Peugeot 407 2.0 HDi Flat spot? - mss1tw
>> On a diesel?!
Yup; been on the commercials for years. 'Think that PSA
call it a dozer valve; it's ECU vacuum controlled and covers
both EGR and FAP regen functions.
Well prone to sticking and linkage issues too.


Well I'll be danged. Everyday's a school day, as they say...
Peugeot 407 2.0 HDi Flat spot? - injection doc
Hi Hugh
Try some concentrated diesel injector cleaner 1st, peugeots are suffering from injector faults. Dont use low sulpher diesel fromsupermarkets and run the tank low before you add a cleaner, drive for 20 miles leave overnite then drive again then refill tank. There is a very effective product called DAE you can find on internet £12+vat a can seems to get rid of hesitations on diesels
Peugeot 407 2.0 HDi Flat spot? - jc2
Spirited driving and changing up at 1500 don't go together.The engine should start to pull strongly at 1800-2200 rpm and too much pulling at very low rpm. is not good for dual mass flywheels(if it has one).
Peugeot 407 2.0 HDi Flat spot? - Hughm
Hey guys - thanks very much for such a great quantity and great variety of replies!

So, diesel injector cleaner first, then try a few more revs, let the Peugeot dealer have a go and don't use very low revs. Phew!

Actually, on my way home tonight I realise its at nearer 1500 - 1800 revs after changing into the next gear that gives me grief.

I'm very pleased with all the comments - again many thanks. I shall try these things and report back.

Kind Regards

Hugh Milsom
Peugeot 407 2.0 HDi Flat spot? - dieselnut
My 2.2Hdi has 6 butterfly valves. 2 separate pipes feed air into the inlet manifold & each has a butterfly. 1 takes air direct from the intercooler, the other has a water to air heat exchanger, presumably to heat the inlet air perhaps to aid warm up & particle filter regeneration. Not butterfly valves in the sense used for a petrol engine, more of an on/off switch effect I think. Then there are 4 more in the head to add turbulence to the air going to each cylinder.
Nice simple diesel engine, not any more i'm afraid.
Peugeot 407 2.0 HDi Flat spot? - Hughm
Wynn's Diesel Nozzle Cleaner/Treatment added when tank filled.

Difference in smoothness and acceleration is marked - and that's after only 30 miles of use!

I'll use the tank up and assess the flat spot problem then.

Kind Regards

Hugh Milsom
Peugeot 407 2.0 HDi Flat spot? - Hughm
The diesel additive/cleaner appears to have done the trick.

Peugeot (Marshalls of Newbury) have checked the car out and can find nothing wrong - even comparing it to another 407 they had in stock.

Problem solved.

Many thanks to all who contibuted.

Kind Regards

Hugh Milsom
Peugeot 407 2.0 HDi Flat spot? - injection doc
Well i'm glad that you took my advice & tried the cleaner, there are those that ridicule what comes in a tin but then they must be living in the past. Not everything that comes in a tin works but diesel injector faults & cleaners mix quite well & well known to curing hesitations on very late HDI engines. I would advise that you use it every couple thousand miles and do give your engine a good burst, they do need driving & not poodling.
Thanks for the feed back & glad it saved you time & stress.
Regards Injdoc
 

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