PicoScope 7 Automotive
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Discovery 4 Turbo
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Darren Fraser
- TwoWaves
- Posts: 54
- Joined: Sat Jul 18, 2020 7:45 am
Discovery 4 Turbo
Good morning all. We're working on a
discovery 4
year: 2010
vin; SALLAAAF3AA548357 with a complaint of oil contamination on the MAF sensors. First thing we checked was whether or not the oil drain pipe mod has been done and the answer is no, however parts have been ordered and it's on its way.
I'm hoping someone here has done a case study on Land rover discovery 4 turbo system.
Checked the bypass valve after test drive and sure enough about half a cup of oil had collected at the intercooler inlet.
We had one code set after initial test drive after reading dtcs. P0235-94
Turbocharger boost pressure A circuit. unexpected operation.
This code has not come back since we emptied out and cleaned the by pass valve.
Sincere thanks to Russ Goff for the link shared on the D4 turbo circuithttps://bit.ly/3c6yhrI?fbclid=IwAR2VfhUUQ1qM1mXIMnlesKoilPW9ZP_fn0VdXIN_liw6d_9osyH-zms5DT4
but Im still not clear as to how so much oil collects at the base of the bypass valve due to the oil drain pipe configuration. The same would happen from leaking turbo seals or excessive internal turbo pressure?
Basically I'm trying to rule out a turbo issue without having to remove the cab. Turbo boost pressure looks identical to my MAP sensor values on the live data stream on our Launch X431 scanner. The ECM using MAP sensor readings for turbo boost? or does the Disco4 has separate boost pressure sensors? I can't find any turbo boost pressure sensor to back probe with a scope.
What I'm trying to do is find parameters that I can measure the relationships between bypass valve and recirculation valve opening and the change in boost pressures when this happens. Way I would be able to "prove" the operation of the bypass valve, whether it's sticking or not, or whether the vacuum line to the valve is chafed like the video I saw courtesy of Joe Hodgson.
I realise that there is plenty advice to say check this, check that, clean this, clean that, or replace this, replace that etc, but what I'm looking for is information that will give me an understanding of ALL turbo components on the D4 AND the sensors so I can actually measure the networking process as it changes from mono to dual mode and back again.
It's really bugging me now why that P0235 code disappeared since I cleaned out the bypass valve because the valve itself was not sticking and vacuum tested ok.
discovery 4
year: 2010
vin; SALLAAAF3AA548357 with a complaint of oil contamination on the MAF sensors. First thing we checked was whether or not the oil drain pipe mod has been done and the answer is no, however parts have been ordered and it's on its way.
I'm hoping someone here has done a case study on Land rover discovery 4 turbo system.
Checked the bypass valve after test drive and sure enough about half a cup of oil had collected at the intercooler inlet.
We had one code set after initial test drive after reading dtcs. P0235-94
Turbocharger boost pressure A circuit. unexpected operation.
This code has not come back since we emptied out and cleaned the by pass valve.
Sincere thanks to Russ Goff for the link shared on the D4 turbo circuithttps://bit.ly/3c6yhrI?fbclid=IwAR2VfhUUQ1qM1mXIMnlesKoilPW9ZP_fn0VdXIN_liw6d_9osyH-zms5DT4
but Im still not clear as to how so much oil collects at the base of the bypass valve due to the oil drain pipe configuration. The same would happen from leaking turbo seals or excessive internal turbo pressure?
Basically I'm trying to rule out a turbo issue without having to remove the cab. Turbo boost pressure looks identical to my MAP sensor values on the live data stream on our Launch X431 scanner. The ECM using MAP sensor readings for turbo boost? or does the Disco4 has separate boost pressure sensors? I can't find any turbo boost pressure sensor to back probe with a scope.
What I'm trying to do is find parameters that I can measure the relationships between bypass valve and recirculation valve opening and the change in boost pressures when this happens. Way I would be able to "prove" the operation of the bypass valve, whether it's sticking or not, or whether the vacuum line to the valve is chafed like the video I saw courtesy of Joe Hodgson.
I realise that there is plenty advice to say check this, check that, clean this, clean that, or replace this, replace that etc, but what I'm looking for is information that will give me an understanding of ALL turbo components on the D4 AND the sensors so I can actually measure the networking process as it changes from mono to dual mode and back again.
It's really bugging me now why that P0235 code disappeared since I cleaned out the bypass valve because the valve itself was not sticking and vacuum tested ok.
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Darren Fraser
- TwoWaves
- Posts: 54
- Joined: Sat Jul 18, 2020 7:45 am
Re: Discovery 4 Turbo
Sorry I didn't leave a space between text and the link here it is again.
https://bit.ly/3c6yhrI?fbclid=IwAR2VfhU ... yH-zms5DT4
It's a very interesting read for those interested in turbo systems. I've posted this thread in the hopes of trying to build a case study on testing turbo systems on a Landover Discovery 4. There's enough of them out there to warrant it.
https://bit.ly/3c6yhrI?fbclid=IwAR2VfhU ... yH-zms5DT4
It's a very interesting read for those interested in turbo systems. I've posted this thread in the hopes of trying to build a case study on testing turbo systems on a Landover Discovery 4. There's enough of them out there to warrant it.
Re: Discovery 4 Turbo
Hi.
This is a link to a part of the document from the manual on LR4(2012-2014).
The whole document can be seen here : https://cardiagn.com/2012-14-disco-4-fu ... 0l-diesel/
There you can find the whole "dance floor" for DISCO LR4: https://cardiagn.com/2012-2014-land-rov ... -diagrams/
.
Unfortunately,in the official manuals, very little attention is paid to Troubleshooting.
It seems ,thay they are constantly talking about repairing a fully functional engine.))
It is difficult to find out, what faults in the mechanical part lead to certain changes in the current parameters.
As you know,in most cases, it is the mechanical failure of the system that leads to the error P0235-94.
The case is complicated by the fact that in contrast to the MB for example, there is only one air pressure sensor.
Because of this fact, learning freeze-frame - doesn't help much.
This is a link to a part of the document from the manual on LR4(2012-2014).
The whole document can be seen here : https://cardiagn.com/2012-14-disco-4-fu ... 0l-diesel/
There you can find the whole "dance floor" for DISCO LR4: https://cardiagn.com/2012-2014-land-rov ... -diagrams/
.
Unfortunately,in the official manuals, very little attention is paid to Troubleshooting.
It seems ,thay they are constantly talking about repairing a fully functional engine.))
It is difficult to find out, what faults in the mechanical part lead to certain changes in the current parameters.
As you know,in most cases, it is the mechanical failure of the system that leads to the error P0235-94.
The case is complicated by the fact that in contrast to the MB for example, there is only one air pressure sensor.
Because of this fact, learning freeze-frame - doesn't help much.
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Darren Fraser
- TwoWaves
- Posts: 54
- Joined: Sat Jul 18, 2020 7:45 am
Re: Discovery 4 Turbo
Thank you so much for the link vasek. It helps me a lot! Ill be sure to post any updates I can figure out how to capture sequential events.