Thread: Leak in EGR system - how to seal?

Originally Posted by mtthsk

Hi Eric,
thanks for the reply. What exactly do you refer to with air control valve? It would fit the symptoms, I guess…

Cheers,
Matt

The 3.0l sdv6 is a sequential turbo as you know. The primary spools up and creates early boost pressure in the system and provides low down torque. As ling as the loads remain fairly low, the secondary turbo is left alone and idles along. When engine load demands it, the air control valve (sitting at the front left of the engine in the line from primary to secondary turbo) is actuated, by solenoid and based on maf and map readings to the ecu. This is basically a flap valve, allows air flow from the primary to the secondary turbo side, the secondary spools up and provides extra power. Seems to me the signal or correlation beyween map and bost control is not working as it should. This video expains it better than me, the ACV is activated at 2500rpm and relies on map and maf sensors along with rpm, throttle etc.

Range Rover and Land Rover 2010 new TDV6 3.0 Advanced Sequential Turbo Diesel Engine Animation - YouTube

I don't know if the gap tool and the Bosch ECU will provide live data with the ignition on and engine off, a number of tools won't.

But if it will, a reading with the engine off would be interesting.

If the MAP sensor (manifold ABSOLUTE pressure) ever reads significantly lower than the AAP sensor (AMBIENT air pressure) then there's an issue with one of them.

I'm my experience, significantly lower = 3-4 kPa.

A static test (engine off) they should be identical, engine running the MAP should be higher.

Based on your current climate and elevation figures, there is something wrong with the MAP sensor or circuit.

It would be handy if anyone on here with a gap tool and twin turbo 3.0 at sea level could post a log from theirs.

Originally Posted by shack

I don't know if the gap tool and the Bosch ECU will provide live data with the ignition on and engine off, a number of tools won't.

But if it will, a reading with the engine off would be interesting.

The tool and ECU allow for recording with ony the ignition on.

Originally Posted by shack

If the MAP sensor (manifold ABSOLUTE pressure) ever reads significantly lower than the AAP sensor (AMBIENT air pressure) then there's an issue with one of them.

I'm my experience, significantly lower = 3-4 kPa.

A static test (engine off) they should be identical, engine running the MAP should be higher.

I agree with you, with everything off the pressure "inside" should be the same as "outside". I have not really noticed this before, thanks for pointing this out!

I just did a ignition on test with a couple of related values:
IMG_7971.jpg

A 25 kPa difference between ambient air pressure and what the sensor is suggesting inside the throttle body seems way off. And it also totally complies with what you figured out based on the first log:

Originally Posted by shack

Based on your current climate and elevation figures, there is something wrong with the MAP sensor or circuit.

This would actually be really good:

Originally Posted by shack

It would be handy if anyone on here with a gap tool and twin turbo 3.0 at sea level could post a log from theirs.

Or even just some MAP readings with engine on and off.

It seems weird to me, though, as the MAP sensor was the first thing I replaced, because the car wouldn't even keep running for 1 second after starting. After swapping it out, everything seemed to be normal until i noticed the reduced performance when hitting above 2500 rpms for the first time a couple of days later.
Would be happy to swap it again and put the faults to bed, though...

Cheers,
Matt

I'm not suggesting that it's definitely the MAP sensor, but that reading certainly seems odd to me.

I'm also surprised it won't run without the MAP sensor, I would imagine most of the fuelling is handled by the MAF's.

I might have expected to see this error if in fact the correlation is wrong, but that said, it is weird they’re different. Baro seems to be from a sensor in the ECU module itself according to the above.

It might pay to did out the ecu from behind the battery and check the connectors are all clean and no water/corrosion has made their way in. The value delta implies a corroded/poor connection giving a value delta.

Originally Posted by DiscoJeffster

Baro seems to be from a sensor in the ECU module itself according to the above.

Hmmmm, where are you seeing that?

Have you chopped off part of the image where it refers to that?

Originally Posted by shack

Hmmmm, where are you seeing that?

Have you chopped off part of the image where it refers to that?

It refers to replacing the engine control module or map sensor as the resolution to inconsistent values hence I’ve inferred it.
I am still not sure where it’s getting the baro value from.

Rereading, that DTC shows up under the 4L petrol. Still, the 3L engine does not show a distinct BARO sensor anywhere (nor does the 4L either).

So, how does it get a Baro value?

If it initially uses the map to get a baro reading then it’s not very dynamic over a journey and then wouldn’t explain the delta we can see. There must be a baro sensor therefore somewhere and I feel it might be in the ECU.

I’m also working the assumption the baro is correct and the map is off in the data above.

Q: Was the map replaced with a brand new sensor? Genuine? Correct one?