Another broken P38? Never!

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RAV

RAV

New Member
Posts
347
Location
Kent, UK
Well, as the title says, mine is broken again - and in typical fashion, just before I'm due to go off on holiday!

Latest issue, driving along, middle lane of motorway, just under 70mph, 3000rpm, start slowing down without warning, revs drop to 2200rpm and stay there, irrespective of where I position the gas pedal..... swing into middle lane, smack hazard light button, just pulling across to Hard Shoulder, small puff of smoke emits from exhaust and she picks up and pulls again... I put it down to one of those "Land Rover Experience" things (not the sort where you rag someone elses Defender etc through mud and ****!)

Next junction, come off and head onto new motorway, shortly after happens again, this time it doesn't pick back up and I end up coasting unceremoniously across to Hard Shoulder, where I call Green Flag to come and take me home. Little Man turns up and without looking at it says "oooh, she isn't very happy!" - yeah, cheers Sherlock.....


Any how, establish that Rangie does this funky loss of revs thing whether in gear or not, so rule out transmission failure - drive Rangie up onto flatbed truck. Get home, drive off flatbed. Arrange for it to go into local independent next day for a looksee, and next morning, drive it there again without incident.....


So, here we are, nearly a week later and she is still in the Garage - so far, its been a new Air Flow Meter Temp Sensor (is that a separate sensor, or part of the AFM itself???) as it was constantly reading the temperature as -38.8 degrees and also established that the hose connected to the EGR was collapsing under pressure so that was swapped out. Then discovered that a rigid plastic hose feeding the intercooler (I think) was collapsing when the engine was running too.. They are still trying to fault find that though.....

Any ideas why the turbo keeps making these pipes collapse? Mucho Confused, followed by Mucho Expense methinks!
 
RAV said:
Well, as the title says, mine is broken again - and in typical fashion, just before I'm due to go off on holiday!

Latest issue, driving along, middle lane of motorway, just under 70mph, 3000rpm, start slowing down without warning, revs drop to 2200rpm and stay there, irrespective of where I position the gas pedal..... swing into middle lane, smack hazard light button, just pulling across to Hard Shoulder, small puff of smoke emits from exhaust and she picks up and pulls again... I put it down to one of those "Land Rover Experience" things (not the sort where you rag someone elses Defender etc through mud and ****!)

Next junction, come off and head onto new motorway, shortly after happens again, this time it doesn't pick back up and I end up coasting unceremoniously across to Hard Shoulder, where I call Green Flag to come and take me home. Little Man turns up and without looking at it says "oooh, she isn't very happy!" - yeah, cheers Sherlock.....


Any how, establish that Rangie does this funky loss of revs thing whether in gear or not, so rule out transmission failure - drive Rangie up onto flatbed truck. Get home, drive off flatbed. Arrange for it to go into local independent next day for a looksee, and next morning, drive it there again without incident.....


So, here we are, nearly a week later and she is still in the Garage - so far, its been a new Air Flow Meter Temp Sensor (is that a separate sensor, or part of the AFM itself???) as it was constantly reading the temperature as -38.8 degrees and also established that the hose connected to the EGR was collapsing under pressure so that was swapped out. Then discovered that a rigid plastic hose feeding the intercooler (I think) was collapsing when the engine was running too.. They are still trying to fault find that though.....

Any ideas why the turbo keeps making these pipes collapse? Mucho Confused, followed by Mucho Expense methinks!
Click to expand...

Inlet air temp is in with AFM. What sort of a garage do you have it in, sounds like your air filter is blocked plain and simple.
 
The inlet air temperature reading of -38.8 is normal for all DSE's fitted with MAP sensor. Its a remnant of the older setup where inlet air temp was used to calculate the density of the air in conjunction with the airflow.
Don't waste any more money on trying to correct that, its got nothing to do with your problem.

As Wammers says above get the simple stuff sorted first, collapsing pipes are indicators of constricted airflow. Chasing senors won't fix such a symptom.

The Intercooler is on the high pressure side of the turbo, it should be bulging not collapsing. This means the high pressure side is experience negative pressure = induction pressure instead of turbo pressure = constricted flow = check for whatever can cause restricted flow, i.e. blocked air filter, collapsed low pressure pipe, siezed turbo.

I wouldn't be massively confident in your indie the way he's going.
 
The Garage is Dakar 4x4 - never had any issues with them before and have always heard good things about them.

They have already changed out the Air Filter for a new one - the problems were still there. The reason they changed out the AFM was down to the fault codes the BECM had generated - I'll get them to check the temperature again to see what it says with the new one on - no point changing it if it ain't broken!
 
In fairness Dakar 4x4 have a very good reputation but I wonder how much of that is founded on BMW engined DSE's.

I don't know if you have Rave but you should look it up if you do and get it if you don't.

On pre EGR diesels the EDC used the intake temp to calculate air volumes for fuel injection based on flow rate from the AFM and density as calculated from the intake air temp.

On EGR equiped DSE's the intake air temp has no input to the Diesel ECU and in fact the sensor that was used to obtain the value on earlier models(which was to the underside of the manifold where the intake pipe goes on) is not even fitted so they will have a hard time changing it.

It has been replaced by the MAF Sensor so now Mass Air Flow is used to more accurately calculate the volume of fuel required for injection.
The reading of -38.8 deg C they are getting on their Diagnostic system is the default value being returned and is of no consequence since the EDC is using the MAF sensor reading for its fuel calculations.
As I said in my previous post ALL EGR equiped diesel P38's return a value of -38.8 all the time.

It is the MAP sensor reading they should be looking at to help them solve your problem.

You are describing a physical problem of collapsing pipes, unless the AFM was blocked it could not produce that symptom. That physical symptom cannot be caused by a sensor or electronic problems. Your fly by wire throttle may well be gone also but that can't cause a positive pressure pipe to suddenly become negative pressure. Push them on the collapsing pipe and query how they cahnged a sensor that isn't there.

BTW if there is an air temp sensor in the AFM (and I'd bet there is) it is still not the one being used by the EDC
 
Last edited:
Just spoken to them, they had reached the same conclusion with the AFM and had swapped it back out for the original as it seems fine.

It looks like its down to a number of pipes failing and collapsing at various times - as one was replaced, it moved the problem elsewhere - could have been caused by the air filter (which originally was a Pipercross one, which in fairness might not have been as clean as it could have been - oops, my bad)

They are just changing out one last piece, then they think its sorted, so hopefully I'll be picking it up again tomorrow, albeit with the wallet a tad lighter.

Although on the plus side, it looks like they have fixed the oil leak whilst they were in there!
 
RAV said:
Just spoken to them, they had reached the same conclusion with the AFM and had swapped it back out for the original as it seems fine.

It looks like its down to a number of pipes failing and collapsing at various times - as one was replaced, it moved the problem elsewhere - could have been caused by the air filter (which originally was a Pipercross one, which in fairness might not have been as clean as it could have been - oops, my bad)

They are just changing out one last piece, then they think its sorted, so hopefully I'll be picking it up again tomorrow, albeit with the wallet a tad lighter.

Although on the plus side, it looks like they have fixed the oil leak whilst they were in there!
Click to expand...

Lesson here is change your air filter often. Because it sounds like that dirty filter has caused all the other problems. And expense.
 
i feel your pain same happened to me a month back i was going on holiday to,that intercooler hose sounds like prime suspect to me,i had same symptoms but my turbo was cooking,i think i have fixed it,parts used thermostat (running cold),air filter(black with bird feathers in it),it would seem the whole car is sh*te even the german bit seems to have spent to much time in land rovers hands,best 4x4xfar they say what a crock of ****,i should have thourght twice when i saw montego bits all over the place;)
 
ex darksider said:
i feel your pain same happened to me a month back i was going on holiday to,that intercooler hose sounds like prime suspect to me,i had same symptoms but my turbo was cooking,i think i have fixed it,parts used thermostat (running cold),air filter(black with bird feathers in it),it would seem the whole car is sh*te even the german bit seems to have spent to much time in land rovers hands,best 4x4xfar they say what a crock of ****,i should have thourght twice when i saw montego bits all over the place;)
Click to expand...

How can you call the motor when your lack of maintenance caused the problems?:doh:
 
Well, got my baby back and she has been transformed!

Looks like the main problem wasn't the air filter (although that was a major contributing factor) - the biggest issue was the hoses delaminating internally which was causing a massive constriction in the airflow when the turbo was spinning up, leading to a loss of power - once the turbo span down again, the pressure dropped and the hose relaxed.
 
RAV said:
Well, got my baby back and she has been transformed!

Looks like the main problem wasn't the air filter (although that was a major contributing factor) - the biggest issue was the hoses delaminating internally which was causing a massive constriction in the airflow when the turbo was spinning up, leading to a loss of power - once the turbo span down again, the pressure dropped and the hose relaxed.
Click to expand...

This problem is highlighted in RAVE service bulletins.
 
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