508 1.6 hdi 2011 very bad mpg and sluggish

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Adrianb
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Joined: 20 Aug 2021, 00:35

508 1.6 hdi 2011 very bad mpg and sluggish

Unread post by Adrianb »

Hello, please help me figure out what is going on with my pug, i have a lot of problems with it but no errors on FAP/diagbox.
1. poor mpg and is not pulling as it used to, not reving fast, it still have kick but not to much. I get no errors as something is wrong and no engine check light on
2.when i accelerate harder or uphill or cruise on motorway but maybe small sloap and requires load on the engine even if the rpm is 2000 the pressure of turbo goes maximum(2.3-2.5) but i don.t feel the power i would say it feels quite opposite and after that the temperature read in the air manifold goes very high 50-60°.
If i rev it to 3000 4000 on idle the pressure is max 1.2 1.3(half)

Tonight i unplagged the maf sensor and car started perfectly normal, on idle was runnig smoother and i thought even the injectors were more silent. Car was reving very nice and fast and had more power. At second start engine management light came.on but still was driving very nice.
The temperature reading though in the airmanifold was very high, 62 if i recall well.

Please any advice on what could it be?

I don.t want to spend to much money and change part after part and not fixing it...though lately seems like this is only what i am doing :( as i spent around 2k on the car and still running poorly.
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myglaren
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Re: 508 1.6 hdi 2011 very bad mpg and sluggish

Unread post by myglaren »

I had similar symptoms but not a severe. Revs were limited to 3,500.

First time fitted a new MAF and instantly back to normal.
Second time, bought a spray can of carburettor cleaner, sprayed the MAF with it and back to normal again. Never needed to touch it after that.
There is a dedicated MAF cleaner now, which I have no experience of, still have 99% of the carburettor cleaner left.

It was a cheap fix. However, your mention of an improbable incoming air temperature may mean that the thermistor in the MAF is also defective.
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Paul-R
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Re: 508 1.6 hdi 2011 very bad mpg and sluggish

Unread post by Paul-R »

+1 for replacing (or cleaning) the MAF. However cleaning wouldn't cure the thermistor fault.
As I get older I think a lot about the hereafter - I go into a room and then wonder what I'm here after.

Inside every old person is a young person wondering what the hell happened.

"Trying is the first step towards failure" ~ Homer J Simpson
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myglaren
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Re: 508 1.6 hdi 2011 very bad mpg and sluggish

Unread post by myglaren »

Agreed, but improvement may help to diagnose further problems.
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Paul-R
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Re: 508 1.6 hdi 2011 very bad mpg and sluggish

Unread post by Paul-R »

Are we sure that the thermistor is in with the MAF? Most are but I believe a few are separate.
As I get older I think a lot about the hereafter - I go into a room and then wonder what I'm here after.

Inside every old person is a young person wondering what the hell happened.

"Trying is the first step towards failure" ~ Homer J Simpson
Adrianb
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Joined: 20 Aug 2021, 00:35

Re: 508 1.6 hdi 2011 very bad mpg and sluggish

Unread post by Adrianb »

Thank you very much for replies you guys are great and hope i will solve it, i will try cleaning/changing maf as it is the easiest fix but i suspect te temp sensor is reading well, just that when the pressure is very high in turbo it forces some heat back in manifold if it makes sense?
Also i suspect something wrong also egr related as disconecting maf is blanking egr as far as i know.
Still don.t understand whh with maf unpugged the air manifold temperature was reading but showing higher 60°.
Adrianb
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Joined: 20 Aug 2021, 00:35

Re: 508 1.6 hdi 2011 very bad mpg and sluggish

Unread post by Adrianb »

Changed the maf and car is the same. It has 190 000 miles, i did an egr test and i hear no clicking noise and then it stop with generic fault error but it does not say the error.
I i am thinking now the egr might be at fault and choking the engine as that would explain when the maf is off gets better aer fuel ratio and engine revs better and idle the engine is more silent?
I have a 1600miles road trip to do asap would a faulty egr cause harm?
Is it better to do the trip with the bad egr or with maf disconeccted?
Thanks
LE: or can i unplug/disconnect just the egr?
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GiveMeABreak
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Re: 508 1.6 hdi 2011 very bad mpg and sluggish

Unread post by GiveMeABreak »

We don't recommend this - or you will have further errors coming up and the engine ECU will start going into backup mode.

Better to find the issue and repair. Ditto for the MAF - it may appear to work better for a while, but this will also start affecting the engine as the engine ECU relies on this for correct metering of the Air entering the engine and so affects the fuelling. If you disconnect it, then the engine ECU will revert to default values that are not ideal or optimised.
Please note, I'm no longer active on the Forum, so won't respond to messages.

Marc