turbo pressure, lagging car

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508c5
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Joined: 15 Oct 2020, 11:37

turbo pressure, lagging car

Post by 508c5 »

Hello,

Peugeot 508, 1.6. THP 156Bhp

I suspect my turbo system might be "lagging" - attached are screenshots from a live data session i recorded today - can anyone make sense of it ? #-o

There are some 20-30 values I can record it these do not suffice...

Blessings from the Holly Land...
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Last edited by 508c5 on 16 Nov 2021, 17:12, edited 1 time in total.
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GiveMeABreak
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Re: turbo pressure, lagging car

Post by GiveMeABreak »

Nothing attached!

Use the full post editor, select attachments and then browse to where the pictures are located, select and then use the 'Place' button to position the pictures within your post.
508c5
Posts: 39
Joined: 15 Oct 2020, 11:37

Re: turbo pressure, lagging car

Post by 508c5 »

508c5 wrote:
16 Nov 2021, 17:07
Hello,

Peugeot 508, 1.6. THP 156Bhp

I suspect my turbo system might be "lagging" - attached are screenshots from a live data session i recorded today - can anyone make sense of it ? #-o

There are some 20-30 values I can record it these do not suffice...

Blessings from the Holly Land...
Image
Image
Image
Image
34fa4632773337eebdf22216208ce7a2.png
34fa4632773337eebdf22216208ce7a2.png
94fc9659437251a7831145ae2978d162.png
34fa4632773337eebdf22216208ce7a2.png
Attachments
910563718ea53952b664dcacc5e6fdf4.png
894d02dc8278ad57ef1a26ef0b8614b9.png
508c5
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Joined: 15 Oct 2020, 11:37

Re: turbo pressure, lagging car

Post by 508c5 »

now ? (i can see them now and before as well)
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xantia_v6
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Re: turbo pressure, lagging car

Post by xantia_v6 »

I can see the graphs.

It does not look like you have any significant boost, the yellow line is more or less flat. Can you see the wastegate actuator rod moving as the engine is revved? Maybe you should check the vacuum on the wastegate control pipe?
508c5
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Re: turbo pressure, lagging car

Post by 508c5 »

Thx, don't know where to look for what you have indicated....is it supposed to be visible?
508c5
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Re: turbo pressure, lagging car

Post by 508c5 »

I looked it up, i think mine is basically the same as the one on video, i will check..thx
508c5
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Re: turbo pressure, lagging car

Post by 508c5 »

So.... I replaced the boost sensor and i guess the difference can be seen on the pics (and the ride also feels better).

However i am not sure if this is "it", Don't know the reference values
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xantia_v6
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Re: turbo pressure, lagging car

Post by xantia_v6 »

The new graphs still look wrong. The reference pressure (yellow line) is the pressure that the ECU wants to see out of the turbo, which is between 1000 and 1500 mBar (normal). The black line is the signal to the wategate control valve, which is topping out trying to give maximum boost. The blue line is the actual measured boost which is sitting around 1000 to 1200 mBar, and nothing like the shape of the yellow line. Where the blue line does peak a little is probably where the throttle is closed with the engine revving and the airflow to the manifold is shut off.

The video you have linked is for a diesel engine, but the principal is similar. You can see the vacuum hose to the wastegate actuator here:
Image

You can see here (under the turbo) the control rod that goes from the actuator to the wastegate itself:
Image

With the engine cold (so you don't burn yourself) you should be able to feel the rod moving when the throttle is blipped.

I am surprised that you are not getting fault codes for under-boost.
508c5
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Re: turbo pressure, lagging car

Post by 508c5 »

Thx

I did get a p0299 fault code but only when reving very strong and in the 4,000 rpms

So if the rod is moving what else could be wrong and treatable..except for the turbo itself failing ?
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Re: turbo pressure, lagging car

Post by xantia_v6 »

If the rod is moving, then it could be a faulty wastegate valve (which can be repaired), or a faulty dump valve ( the black thing with wires on the end of the turbo). If you google for mini N14 (the same engine), you will find a lot more results, but of course the engine is packed differently into the engine bay and uses different diagnostic tools.
508c5
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Re: turbo pressure, lagging car

Post by 508c5 »

The actuator (dump valve) looks fine and is fairly new, he is always my no 1 suspect in cases like this.., i'll try to look at the wastegate

Thx
508c5
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Re: turbo pressure, lagging car

Post by 508c5 »

Looking at the graphs...it seems as if that the yellow/purple and the blak/blue combination have "switched" places after i replaced the sensor. Previously yellow/purple were fairly flat and black/blue were "all over the place" - can we deduce something from this..?
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xantia_v6
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Re: turbo pressure, lagging car

Post by xantia_v6 »

Nothing has changed, except the scan tool has chosen different colours for each measurement. Look at the labels.