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Discussion Starter #1
I own an 07 plate 407 SW 2.0 136 HDi GT Auto.

Recently (last couple of months) it seems to have lost horse power. Acceleration feels slower overall, but sometimes when accelerating it seems to get to 30mph in 3rd then accelerate at a painful rate with my foot right down, with the revs stuck at about 3k and not increasing.

On motorways it goes ok at a constant speed, but as soon as there is a slight hill I can't accelerate and am stuck at the speed I'm doing with my foot flat to the floor. On longer hills I even lose speed by the time I reach the top. With cruise control on it can go from 70 to 65 by the top. Not possible to easily overtake quickly on the flat either.

After some research I thought it might be the egr valve getting stuck open, so I disconnected it and it did improve slightly, so I've now blanked that off. Mpg has improved from 42 to about 47-50 but I still have the acceleration issue.

I was then wondering if it was the MAF sensor? So I disconnected it to test and I didn't notice any different in performance or how the car runs.. although I've only had chance to give it a quick run on flat roads near my house without and then with it connected.

Just to check I disconnected the right thing.. am I right in thinking the MAF sensor is directly behind the air intake box/filter with the connector plugged into the side? If so will be very easy to replace.

Can the sensor be tested with a multimeter whilst connected to the car? probing the wiring for voltage output? IF so what would I be looking for? Just changes in voltage to indicate the sensor is working?

Finally, if I decide to replace it, I've seen MAF sensors for sale on ebay for £40 which seems cheap. Are these OK? Anyone recommend a good reliable ebay seller? Or an alternative online store to buy from? Or should I avoid the cheaper ones and pay more like £100 for a known genuine one?
 

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You'll probably read this a lot on here. But, get it diagnosed.
There is no point pointing at random stuff under the bonnet and blaming it for faults, spending X on a replacement and it not working.
There is a map on here with the locations of people with diagnostics equipment who, for either a few pounds or a cup of tea and a bacon sandwich will do a check for you. And don't go anywhere where they use generic readers, they're crap. i tried one once, apparently I had an ABS sensor fault. Which one, there are 4. Good job I already knew.
If it costs you a fiver and points to a £5 part, then you know. Spending £40 on a new part and it not fixing it is not good business practice.
Oh and, welcome :D
 

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Firstly don't know if it applies to Peugeots. On the BMW TD4 engine it was always recommended that you unplug the MAF and let the engine run on the ECU pre programmed config, if it performs OK then this points towards a faulty MAF. The MAF only comes in to play when the engine has reached normal operating temperatures.
 
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Yes you are looking at the right thing.

I would try to find a fellow forum member close by with a known working MAF and do a swap, only temporary, to see what happens, as you say it is only a 5 minute job.

Please don't be tempted by ebay MAFs, they are not always very good, they are cheap for a reason, and if the MAF swap proves yours is rubbish then try to buy a VDO/Siemens one ( check online for deals at Europarts or local motor factors )
 

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Discussion Starter #5
Thanks for the advice.

My existing one is a Siemens one so would definitely want to replace with the same.

Will take a look and see if anyone is close to run a diag on the car for me.
 

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Discussion Starter #6
Quick update.

I've not had time to look into getting it diagnosed yet.

But my wife owns a Pug 307 CC Sport with the same 2.0 HDi engine. She has just changed her car but we still currently have the 307 until we get it MOT'd and then we will sell it... anyway, I swapped the MAF over with my car as I know the 307 is working fine and it made no difference at all. I even put mine into the 307 and it performed OK.

So it isn't the MAF and it isn't the EGR because I have it blanked. I therefore will need to get it diagnosed, but until I have the time to arrange that what else could be causing the issue? Main symptom is a lack of power to accelerate, and sometime a surge of revs before the auto box changes up a gear (is that overboost?). Could it be a sticking turbo vanes?

Anything else I could try swapping over to test with the 307 while I have it available to utilise?

Strange as there really are no specific symptoms. Just very slow acceleration.. probably 0-60 in 20 seconds, if not more. Quite embarrassing on the motorway when trying to get up to speed and small cars and lorries are overtaking you.
 

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As has been said a diagnostic is key, could be third piston on fuel pump not engaging to maintain fuel pressure. Try cleaning the tube connecting the MAP sensor to the top of the intercooler, there is a brass restrictor in there that can block.
 

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yes just fixed mine!
I changed the starter moter and when i started it again i had no turbo???
eventualy found a split in the rubber elbow connectors of the vacume pipes
look for theses red things near your altenator
theres a cap on them you can lift with a screwdriver and a tiny sponge filter that can be cleaned under a tap with some fairy liquid
check every single rubber connector on all ends of these pipes (one by one so you can put them back correcly)
I had 2 splits and one that was suspect.. replaced them all with lenghts of strait pipe and cars running fine again.
theres also a selenoid hidden far top left (when stood in front of the car) behind the engine but I didnt need to touch that one for my problem. good luck

for googlers "407 turbo not working"

no engien management light
car was slow... sounded like a tank, had power but no acceleration whatsoever (close calls joining roundabouts)
no turbo whistle
no fault codes on generic obd2 reader
pp2000 had "turbo pressure to low"
 

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I had no white blue or black smoke the car was 100% untill I turned the key one day and it wouldnt start. while changing the starter moter I think I pushed one of these decaying rubber connectors too hard as it was in the way. I also have a 407 parts car that had the same problem. When I looked at that car... theres a plastic Y connector on the same pipes that had snapped Off. 2 cars fixed :sneaky: total cost 70 pence
 

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puran






hi i got Peugeot 407 how difficult to clean egr valve
i have 2006 peugeot 407 2.0 hdi auto al4

egr is fairy easy (if you lose a bolt it will end up in the heat shield of the turbo at the back under the engine lol)

There are aerosols that can do this without dismantling the car but at the age of the 407 I wouldn't recommend it. I once used wyns turbo egr cleaner on a Mondeo and the engine reved itself to the max! I disconnected the battery and ripped off the fuel lines but it went with spectacular bang and allot of smoke. Apparently all the Marmite tar shite that gets cleaned out is combustible and the Mondeo experienced something called “diesel runaway”

so take the parts off the car

use petrol first with a paint brush. there's a plastic cover that needs to be removed to get to the bearing and latch that opens the valve... make sure you can fully open it and fully close it without it sticking. I covered my bearing in copper grease... I don't yet know whether that was a good idea.

if your egr is clogged its likely that the cooler will be as well


also take the rocker head cover off and scrape as much as you can out from the air intake ports using a tea spoon and a hoover to make sure none of it drops into your engine

the rocker heads gonna be rammed with the marmite goo shite as-well i soaked mine in fairy liquid for 2 days then jet washed it.... then used mr muscle.... then used lucas aerosol

lucas (aerosol) turbo egr cleaner worked well for me

you get 4x as much for the price of most products like this and I got mine on amazon

product says to disconnect intercooler pipe first... and when i did this a shed load of oil came out so i cleaned it with petrol


I also used mr muscle on the egr (not the intercooler or air intake ports under the rocker cover)

but after all this hard dirty work! The thing moves! I finished it today and just had 130mph down the A1. I reckon I could have balanced the edge of a 2 pence piece on the dash throughout.
 
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