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Discussion Starter · #1 · (Edited)
Hi,

Have been struggling with low boost during low revs since i have bought this car,above 2400rpm it seems to boost ok,but at anything below that it just feels very sluggish like its getting some boost but just not enough.

Car is a 2.0 110 DW10ATED

Hooked up planet to look at some live data and on checking the turbo referencve and actual pressure figures i noticed that my actual measured pressure is always below the reference pressure.
Heres the figures i get whilst sitting on the driveway have been unable to get data whilst driving

atmospheric pressure 1012mbar
803rpm ref press-1129mb actual measured pressure 988mb
1000rpm ref press-1153mb actual measured pressure 1012mb
1500rpm ref press-1224mb actual measured pressure 1035mb
2000rpm ref press-1365mb actual measured pressure 1082mb
2500rpm ref press-1459mb actual measured pressure 1153mb
3000rpm ref press-1390mb actual measured pressure 1270mb
3500rpm ref press-1435mb actual measured pressure 1435mb

the figures for 3000rpm reference pressure look a little out of sync but maybe i wrote them down wrong as was getting late last night when i was doing it .

Tonight i had a look at the vacuum side of things and as a mate had an electrovalve solenoid spare still in its box i thought i would try changing that as it wasnt a big job to do,
After changing it over the figures were pretty much identical to the figures i was getting with my own valve so at least i know my own valve is good.

After that i got my vacuum gauge out to try and see what pressures i was getting,on the feed pipe to the turbo solenoid i am getting appx -500mbar and am getting the same out of the other side of the solenoid too.
i have read somewhere that i should be getting around -700mbar so then decide to see what the vacuum pump itself was putting out and sure enough i am getting -700mbar when connecting my gauge directly to the pump.

I then plugged the connector back onto the pump which has a big pipe going to the brake servo and 2 smaller outlets for the turbo solenoid and one to the vacuum reservoir
When i connect my gauge onto either of these 2 smaller outlet i am only getting -500mbar

At which point i thought is my brake servo loosing vacuum as there is a very slight hiss when i press the brake pedal from behind the glovebox but the brakes have always felt fine

When i disconnected the pipe from the brake servo and blocked it off i was still getting -500mbar on the 2 small outlets just beside the pump..

so then i thought maybe the pipe to the servo has a small leak that i cant detect so decided if it is the pipe then i have nothing to lose by cutting it closer to where the 2 small outlets are and blocking it off again but after doing this i am still only getting -500mbar at the small outlets ,

so my theory of it being the brake servo leaking is is wrong :(

Can anyone confirm if the vacuum at either of these 2 small outlets should be the same as what i am getting when connected directly to the pump or do you lose a little due to the pipes getting smaller???
Doesnt make sense to me as i would have thought the vacuum should be the same anywhere on the circuit regardless of the pipe size or distance from the pump...

Have tried blowing and sooking at both these small outlets but doeasnt seem to be making any difference :rolleyes:

I guess my next move would be to try connecting the pump directly to the turbo solenoid and see if that helps it boost any better.

If it does when i get home tomorrow night then i guess the problem lies in the connector where the 2 small outlets come out but would be interested to hear if anyone else has had the same problem or similar and could confirm that the pressures im getting at the pump and at the 2 small outlets are correct or am i on the wrong track altogether which wouldnt surprise me

thanks for any advice

Sorry for long winded post tried to simplfiy it but that was the shortest i could :p


Regards Terry
 

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Can anyone confirm if the vacuum at either of these 2 small outlets should be the same as what i am getting when connected directly to the pump or do you lose a little due to the pipes getting smaller???
If there is no gas flow (i.e. no leak) the pressure should be the same, regardless of pipe diameter.
 

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Try clearing the 2 outlets with a small nail or screw as they block up around the base of the 2 outlet connector,I have came across this often if not a new pipe cures it.
 

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Discussion Starter · #4 ·
Small update wasnt home till late tonight and its pretty miserable out so didnt spend to long before i was soaked...

If there is no gas flow (i.e. no leak) the pressure should be the same, regardless of pipe diameter.
Yeh thats what i thought Ian Just needed to hear it from someone to confirm it in my head :)

Try clearing the 2 outlets with a small nail or screw as they block up around the base of the 2 outlet connector,I have came across this often if not a new pipe cures it.
tried poking a needle down it ,no luck
Then tried precision screwdrivers with no luck
As i have already cut the pipe going to the servo i thought i need a new pipe anyway so got the drill out and used 3mm bit to drill down the 2 small outlets right through into the pipe so there clear as a bell now and i am getting the same reading (appx -680mbar) at the outlets as i am connected directly to the pump.

So i thought great i have cracked it and just need to buy a new servo pipe.

i then checked the pressure at the feed pipe to the turbo solenoid and again -680mbar but when i checked what was coming out of the solenoid on the connection that goes to the wastegate i am only getting -500mbar :confused:

This is with the new solenoid.
Thinking maybe its faulty or something i tried connecting up my old one and when i did i am getting slightly even less on the outlet side (just under -500mbar)

Am i barking up the wrong tree here or what??
I realise the vacuum should be the same on the outlet side at idle but is -500mbar enough to keep the wastegate closed??
or are both my solenoids dodgy??

And when i use planet to check the measured turbo pressure its still way below the reference pressure whichever solenoid i use ,my old one or the new one.

are the pressures i wrote in my original post wrong ?
Should the measured pressure be closer to the reference pressure than what i am getting?

forgot to mention in my first post as well planet is reporting my dpf as being clogged but the car is not giving me any messages on the MFD or any engine light regarding the dpf so i am assuming its not clogged to bad yet although i will have to get that sorted.

or is this looking like a sticking or stuck wastegate ? which looks like a pure pig of a job..
Again sorry for the long post an the million questions

Thanks again for any help or advice


Terry
 

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It would seem that both the solenoid valves are leaking vacuum. Whether that is a problem, I can't say, but if it is not, it does sounds like something is preventing the wastegate closing fully.
 

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Discussion Starter · #6 ·
It would seem that both the solenoid valves are leaking vacuum. .
Yeh its seems that way,i will try using one of the other solenoids for the EGR or doser valve tomorrow night if its dry and see what sort of pressure i get on the outlet side of them.

it does sounds like something is preventing the wastegate closing fully.
Is there an easy way of checking this or do i need to remove the turbo?
access really isnt the best
Hope not as i am struggling for time over the next couple of weeks and cant afford to have the car lying in bits :D
 

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Discussion Starter · #7 ·
Havnt made a lot of progress with this due to work,
but as my dpf was showing as clogged and i was getting 18mbar pressure difference at tickover i took it off split it and cleaned it out the best i could before the guy at the garage carwash started getting nosey as to what i was washing :(
just incase that was causing my low boost due to the engine not breathing properly so thought best to get that out of the way first
could have done with washing it longer but i definately got most of the crud out.

anyway dpf is back on,
checked additive tank which was more than half full,
reset both counters using planet to zero

but planet still shows dpf as being clogged and the pressure difference is down to 5.9mbar on tick over

Is 5.9mbar still too high a reading at tickover?????

Also still curious if anyone can confirm if my readings for the turbo reference and actual pressures are normal or not??

still to check out the vacuum side of things again and then try and look at the wastegate and actuator too

Terry
 

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Discussion Starter · #8 ·
Another small update,

Not had much time to look at car but tonight had another check for any boost leaks but couldnt find any.

Then i started to take off the pipes to the turbo to try and have a look at the wastegate,
Once i got visible access to it i noticed that the rod from the acuator and the arm going to the wastegate are still nice and new looking shiny metal,
i would have thought they would have been all rusty.

So i am wondering if maybe someone has replaced these parts before i bought the car and maybe havnt adjusted the rod properly and maybe thats holding it open??


Is there any way of checking if it is adjusted right??
I can just about get to the 2 nuts that adjust the actuator arm but how do i know where to set it??


Also still wondering about the turbo pressures in my first post and the DPF pressure in my post above,would be really grateful if anyone had any input to point me in the right direction

Regards Terry
 

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I have checked the Service Box Procedures for any wastegate adjustment instructions, but found none - this is all I could find:

9. Turbocharge pressure
Engine speed Turbocharge pressure
Between 2500 and 3500 rpm 0,95 ± 0,05 bar

10. Air supply circuit
10.1. vacuum pump
Designation Negative pressure
Idling 0,8 ± 0,2 bar

10.2. Turbocharger wastegate valve
Designation Negative pressure
Idling 0,8 ± 0,2 bar

Very different to the values in your first post. The way I read it, the idle pressure should be a vacuum of 0 to 600mbar (you seem to have that - 24 mbar vacuum), and the 2500 to 3500 rpm should be 900 to 1000mbar above ambient pressure (you have only 141 to 423 mbar).

You could try shortening the rod, which should delay the opening of the wastegate (I think). It should not affect the idle pressure, but hopefully would bring the 2500 to 3500 readings within the bracket. What those reference pressures you quoted are is a mystery.
 

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Discussion Starter · #10 ·
Thanks Ian :)

ill keep searching on here and google and have another freezing session lying under the car tomorrow night,feel like im getting no where...

Terry
 

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If you get the 2500 to 3500 boost in the bracket, it should increase the boost values in the intermediate range of revs.

Aim for 1000mbar boost at 3500.
 

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Discussion Starter · #12 ·
Aim for 1000mbar boost at 3500.
so that would be 1000mbar boost plus atmospheric pressure should give me around 2000mbar measured pressure???


think in my first post at 3500rpm i am only getting 1435mbar measured pressure
 

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Discussion Starter · #13 ·
just seen you edited your post a couple back :)

i will see if adjusting the actuator rod makes any difference,bit of a pain but im running out of any other ideas,

will report back when i get a chance to do it,hopefully tomorrow night.

yeh that reference values are what planet was giving when connected to the car,they were taken sitting stationary in the drive whether they become different if the car is moving i dont know, will maybe need to try and check,possibly the ECU knows its not under load

Cheers Terry
 

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It may be that the reference pressures take into account the air flow rate, which is low when the engine is unloaded, whereas the pressures I got from the Service Box relate to the engine under load, which implies a higher flow rate (need more air to burn more fuel to make more power).

In that case you may not be able to bring the 2500 to 3500 figure up as high as 2000mbar on no load, but adjusting the actuator may bring the midrange figures up to the reference values. Worth trying ;)

EDIT: Looking again at the figures, I think I misinterpreted the Service Box idle figures - they are for the vacuum control side, not turbo pressure.

Also, that dip in your readings at 3000 rpm does suggest the wastegate is opening more than it should at that point.
 

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Discussion Starter · #15 ·
Finaaly fixed

Been a while as i kept meaning to update this thread but kept getting distracted :)

Car was actually fixed months ago,,after checking for boost leaks,repeatedly power washing out the dpf,playing about with the turbo acuator rod,replacing turbo vacuum solenoid,replacing vacuum hoses all to no avail.

I then noticed the airflow reading when connected to planet didnt really seem to move much,noticed it before but it just didnt click...i then unplugged the MAF and the car ran exactly the same as when it was plugged in,no difference at all,,and also when i unplugged it i expected it to maybe throw up a fault code which it didnt :confused:

So onto ebay got a cheapish MAF (£28) Fitted it in minutes and hey presto car running like a dream ,boost back as it should be :)

Cant believe it was such a simple fix after all that hours freezing in the winter lying under it trying all the other things i tried :)

Never mind got there in the end.

Cheers for all the help guys and sorry for being so slow to update the thread

Terry
 
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