Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

Feels as though there is no turbo boost under 2000 rpm, once over that it takes off, sort of feeling a dud MAF gives but I have swapped the one from my wifes car which is identical and it makes no difference.

My thoughts are a sticking turbo boost control or a vacuum leak somewhere. Anyone any suggestions? Thanks

Peugeot 406 hdi estate - Very little power under 2000 rpm - hardway

Yeah,

I'd start by checking all the small bore black piping to/from the turbo boost prerssure solenoid.

and check the vac pipe from the vac pump,

Could be there's a leak there limiting the vac pressure until higher engine speed.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

Thanks, I did do a cursery check of the piping and couldn't see anything amiss but I will do a more thorough check. I certainly feels as though the turbo is under performing at low revs.

Peugeot 406 hdi estate - Very little power under 2000 rpm - hardway

There's varients on these so for accuracy I'm going to need the code from the middle of the VIN number,

RHY,RHZ or whatever it reads.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

Yes I have noticed that, I have three, two running and the other the spares dept. I will get back to you if I don't have any success.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Gibbo_Wirral

Is the wiring to the MAF ok? Can Planet see and query the sensor readings from it?

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

That had crossed my mind but the power loss is much greater than caused by normal MAF failure , I think I did try running it with the MAF disconnected but can't remember what the result was - I'm getting old. Will have to try it again.

Peugeot 406 hdi estate - Very little power under 2000 rpm - hardway

Still waiting for the rhy,or whatever it is code.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

Sorry about that, they are both RHZ.

Peugeot 406 hdi estate - Very little power under 2000 rpm - hardway

Ah progress,

Try swapping from your spares car the Manifold Abolute Pressure Sensor to your problem car/

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

I have swapped the one on the intercooler, is that the one you mean?

Peugeot 406 hdi estate - Very little power under 2000 rpm - hardway

I'll be honest it's been so long I can't remeber!

It's certainly in the induction system,

little black doodad with a three wire multi plug connector and held in with a single fastener,

remove same and wiggle loose,

When free there's a cage afair over the sensor element itself.

If this is the part you've already swapped then report and we can move on.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

Sounds like it, certainly a pressure sensor on the outlet side of the intercooler, didn't make any difference though.

Peugeot 406 hdi estate - Very little power under 2000 rpm - hardway

Can't you get hold of Peugeot Planet diagnostics?

A full scan and data read would clear this up.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

I have one, in fact I have two but once the car is selected neither of them will connect to it, or the other car.

Peugeot 406 hdi estate - Very little power under 2000 rpm - hardway

The plot thickens!

I'm taking it that the EML does come on with key on engine off?

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

Not noticed, I will check.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

The plot thickens. I have just done what I should have done in the first place and removed the engine cover and shone a light down the back, the outcome was that the vacuum hose to the turbo wasn't connected to anything! I had difficulty in seeing it originally as it was underneath the other hoses.

I looked for where it should be connected and couldn't find anything, I then looked at both the other cars and found it should be connected to the uper connection of the solenoid in the centre of the bulkhead but on mine it had a rubber cap over it. I took the cap off and checked for vacuum, there was some but it didn't feel very strong, I checked the other hoses and couldnt find any leaks.

I drove the car a mile or so with the pipe connected but didn't notice a lot of difference altthough the engine was cold. I shall be doing a couple of hundred miles in it this afternoon so will be able to tell better. If vacuum is from the same source as the brake servo this would explain why the brakes have never been all that good on this car but the other one nearly puts you through the windscreen. Could it be a faulty vacuum pump do you think?

I have had the car a couple of years and done about 20k miles and its always been OK so why the power had dropped off now is a mystery but somebody has obviously got at it before I had it.

Edited by Peter.N. on 30/10/2017 at 12:30

Peugeot 406 hdi estate - Very little power under 2000 rpm - hardway

Sounds like you caught the fault yourself.

Definately need good vac from the pump.

So swap the one from the other car.

And a simple brake/servo/vac test is start the car give it a few revs then engine off,

pump the brake pedal a good few time as hard as needed then hold the pedal down with your foot then restart.

On a good system the pedal should dip down noticably.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

I will just check that the solenoid is not faulty if not I will do that. I have been to Surrey and back this afternoon 200+ miles and there is a slight improvement since I connected the turbo pipe, it starts to pull about at about 1700-1800 rpm where as before it was about 2000 rpm.

Peugeot 406 hdi estate - Very little power under 2000 rpm - Peter.N.

Problem sorted, it was the vacuum pump. Thanks for your input.

 

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