Disco 2 Wastegate strange behaviour

Michalis Karatzis · Jun 26, 2019

sierrafery said:
That's really strange, the stock overboost limit is at 1.42bar(142KPa) calculated by the ECM by extracting the AAP from MAP so to record overboost when MAP is at 230 you should have AAP 88, was it like that?

AAP at this altitude is always 97-99

I was thinking maybe the ECU sees a different (slightly higher) instantaneous MAP than what I see on my Nanocom when getting close to 142 because of lag in transmitting the data.
I can't record data on my Nanocom so is what I see on the screen when driving around.

sierrafery · Jun 26, 2019

You have to record "inputs fuelling" on SD card and save the file to the computer, it's the only way to see all the readings at the same time and analise them well... on instrument mode you can see the calculated boost in bar so you should see 1.42 when it goes to overboost

sierrafery · Jun 26, 2019

Anyway it's hard for me to believe that your wastegte actuator is still opening with ony about 6 threads left on the rod cos it's very tight like that... i'd replace the actuator if i was you to rule out a leak through it

Michalis Karatzis · Jun 26, 2019

sierrafery said:
Anyway it's hard for me to believe that your wastegte actuator is still opening with ony about 6 threads left on the rod cos it's very tight like that... i'd replace the actuator if i was you to rule out a leak through it

I will find a non faulty actuator from a friend with a td5 to try out and report back.

My Nanocom is a very old mk1 version with no sd card. It needs cables and cds that I don't have in order to connect to a laptop. Maybe I can find a newer model from a friend.

Michalis Karatzis · Jul 19, 2019

sierrafery said:
Anyway it's hard for me to believe that your wastegte actuator is still opening with ony about 6 threads left on the rod cos it's very tight like that... i'd replace the actuator if i was you to rule out a leak through it

So I tried another actuator and the behaviour is exactly the same. So my actuator and modulator are ok.

I took another measurement while driving and at full throttle I got 230kpa on my nanocom (MAP) and 260kpa on the gauge I connected before the actuator (see pic). Is this difference within limits before and after the intercooler?

sierrafery · Jul 19, 2019

You have a boost leak between the turbo and inlet somewhere

Michalis Karatzis · Jul 19, 2019

sierrafery said:
You have a boost leak between the turbo and inlet somewhere

Which I can't find...

Michalis Karatzis · Sep 6, 2019

sierrafery said:
You have a boost leak between the turbo and inlet somewhere

So the search is still on. Today I managed to remove my intercooler and gave it a flush with petrol. It was oily and I hoped that the difference in pressure before and after will be sorted but no...

I can't find a leak, silicone hoses are in top shape, the intercooler is clean with no sign of leaking and turbo also looks healthy (it does produce 260kpa at the wastegate).

Give up or something else to do now?

sierrafery · Sep 6, 2019

At 260 Kpa the wastegate should be wide open while your's is closed(which is normal being so tight), normally 0.3 bar pressure drop between the turbo and MAP is too much, was the inlet manifold cleaned after the EGR was removed?... if not make sure it's not clogged with gunk

Michalis Karatzis · Sep 7, 2019

sierrafery said:
was the inlet manifold cleaned after the EGR was removed?... if not make sure it's not clogged with gunk

This I don't know, I didn't do the removal. So next thing on the list is cleaning the manifold...

Little art · Sep 8, 2019

Follow, as looking for the same issue.

Michalis Karatzis · Sep 26, 2019

So I did a boost leak test using a smoke device that didn't show any leaks. At the same time I tested another MAP sensor with no obvious difference (same boost figures as before). So no leaks and MAP is healthy. Manifold looks clean but I used a cleaning spray to clean it just in case it could help (no difference).

So I don't know what else to try now. Any recommendations?

sierrafery · Sep 26, 2019

I'm out of ideas as well, very strange and unexplainable

Michalis Karatzis · Sep 26, 2019

Has anyone else measured the boost pressure before the intercooler? The pressure that the modulator or actuator see?

stuu · Sep 26, 2019

Michalis Karatzis said:
Has anyone else measured the boost pressure before the intercooler? The pressure that the modulator or actuator see?

I put a boost gauge on mine just out of curiosity Wastegate side or metal boost pipe side from flat out at 1000 revs it builds upto approx1400revs 18psi and stays there till 4k I don't know if that's 100% correct or what its ment to be at but on a 194k engine I'm not complaining.
Hope this helps in some way

Michalis Karatzis · Sep 27, 2019

stustrong said:
I put a boost gauge on mine just out of curiosity Wastegate side or metal boost pipe side from flat out at 1000 revs it builds upto approx1400revs 18psi and stays there till 4k I don't know if that's 100% correct or what its ment to be at but on a 194k engine I'm not complaining.
Hope this helps in some way

To me it seems a bit low but nothing to worry about. 18psi is 224kpa and that is before the intercooler. I would a guess a slight drop of 5-10kpa so you are getting at least 215kpa at the inlet manifold. Ideally you want 230-235kpa at the inlet.

In my case to achieve the 230kpa at inlet I need to push 260kpa before the intercooler. And I can't understand why...

sierrafery · Sep 27, 2019

Did you double check with another gauge cos as you said if there are no leaks and with that tightened wastegate of your's you should be in overboost with 260Kpa at the wastegate, IMO it's technically impossible to have 30Kpa drop with no leak or no restriction

Michalis Karatzis · Sep 27, 2019

sierrafery said:
Did you double check with another gauge cos as you said if there are no leaks and with that tightened wastegate of your's you should be in overboost with 260Kpa at the wastegate, IMO it's technically impossible to have 30Kpa drop with no leak or no restriction

I didn't double check because I don't have another gauge in that range. But the 260kpa does makes sense with the wastegate tightened like this. And if the wastegate is loosened to the normal length then I get 230kpa at the wastegate but MAP shows a max of 210-215kpa. So the drop still exists.

Is there any chance that someone messed up with the ECU map and the MAP undereads and fuelling is adjusted to the lower MAP values? So the boost at the inlet is not 230kpa but 250kpa but fuelling is not accordingly increased? So the power is "normal" although boost is high?

(am I going crazy....?)

sierrafery · Sep 27, 2019

Michalis Karatzis said:
But the 260kpa does makes sense with the wastegate tightened like this.

that does make sense, what doesnt make sense is that in that situation it doesnt go to overboost... you might have a point with the messed up fuel map though so find a way to fit the gauge to the inlet, eventually tap into the EGR bypass tube

Michalis Karatzis · Sep 27, 2019

sierrafery said:
that does make sense, what doesnt make sense is that in that situation it doesnt go to overboost... you might have a point with the messed up fuel map though so find a way to fit the gauge to the inlet, eventually tap into the EGR bypass tube

Tapping into the EGR tube
is next then

Disco 2 Wastegate strange behaviour

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