A Challenge To Mechanics

ScroobiusPip · Mar 9, 2012

Hi All,
Got a problem with my 2.5 dHSE auto 2001 RR, low on power and when ticking over the revs will suddenly drop, sometimes stalling, and it also tends to stall when you put it in gear.
It's had a new diesel pump, fuel filter, air filter, all the leak off pipes and end injector blank. The needle lift, injection solenoid and lifting pump have all been checked and are OK, and I've stripped and cleaned the air mass, but I still have the problem, any suggestions welcome because I'm out of ideas now.

Thanks,
Pip.

Saint.V8 · Mar 9, 2012

Only things not on that list is the Manifold Air Pressure sensor, the EGR valve, turbo hoses, the Crank Position sensor breaking down or the intercooler...

Check the little pipe to the MAP sensor isn't blocked or split....

Check the EGR valve isn't gummed up...

The Turbo hoses do delaminate internally and can either block the airflow or collapse...

The Intercooler gets clogged regularly so check that too...

If the CPS is breaking down, it will cause a spurious reading to the EDC and mess up the fuel quantity calcs etc...

Others more knowledgable could probaby point out some others too....just don't give up hope and :welcome2: btw.

ScroobiusPip · Mar 9, 2012

Cheers, that gives me something else to go at.

ScroobiusPip · Mar 10, 2012

Forgot to ask, I take it none of these show up on a diagnostic as I've had it at a LR specialist and all they said was it pointed towards the diesel injector pump, but I know that's new.

wammers · Mar 10, 2012

ScroobiusPip said:
Forgot to ask, I take it none of these show up on a diagnostic as I've had it at a LR specialist and all they said was it pointed towards the diesel injector pump, but I know that's new.

Tickover and engine speed are controlled by fuel quantity servo in injection pump. This is driven by ECM from speed signals recieved from crank sensor or in the case of throttling from the throttle position sensor on the throttle pedal. If the speed sensor detects a slow down at tickover or a slow down because of load. Car being put in gear, steering being turned, alternator loading up, the ECM increases the fuel quantity to compensate. This is clearly not happening on occasion. If there is an intermittent fuel quantity problem it should be recorded as a fault in the ECU.

ScroobiusPip · Mar 10, 2012

Well as there is nothing showing on the diagnostics, I'll take it that's all OK

wammers · Mar 10, 2012

ScroobiusPip said:
Well as there is nothing showing on the diagnostics, I'll take it that's all OK

Can't be if it's stalling. Throttling is done by adjusting fuelling. Not with an air valve. Theoretically if the ECM detects from the crank sensor a fall in RPM it should adjust the fuel to increase the speed. When the throttle position sensor is at rest the idle speed is maintained at a preset held within the ECM. Fuelling is adjusted by the ECM to compensate for loading. If it stalls when you select gear or turn the steering and load the engine. Either the crank sensor is not picking up the falling speed or the ECM is not reacting to it or the fuel quantity servo is not reacting to the ECM. Simple as that.

ScroobiusPip · Mar 10, 2012

Cheers Wammers, I'll check it out, but 2 garages have had it hooked up and they both say nothing is coming up as faulty.

ScroobiusPip · Mar 10, 2012

The engine does seem slow to respond to the throttle, in that it doesn't rev for a split second after the throttle is pressed, as this is the first RR I've owned, I'm not sure if this is standard.

Datatek · Mar 10, 2012

ScroobiusPip said:
The engine does seem slow to respond to the throttle, in that it doesn't rev for a split second after the throttle is pressed, as this is the first RR I've owned, I'm not sure if this is standard.

Not normal, mine is not like that, revs immediatly.

Lots of travel on the throttle peddle before it really gets going is normal though.

wammers · Mar 13, 2012

ScroobiusPip said:
Well that was sort of interesting, removed the MAP sensor and found someone had already blocked the tube with a penny, so left it off and took it for a quick spin, still no power but it wasn't stalling in gear, maybe because it ticked over at about a 1000rpm as opposed to 800rpm with it on, so think I'm going to try a new MAP sensor and go from there. All comments welcome.

How do you block the MAP sensor with a penny? The hole in it is only about 3mm. Do you mean the EGR feed pipe.

ScroobiusPip · Mar 15, 2012

OK, updtae, disconnected the MAF sensor and that made no difference, so then took the EGR valve out, found a penny blocking the hose so someone had already tried this, and that made no difference, other than ticking over at about 1000rpm instead of 800rpm, so it didn't stall in gear any more, but still no power. So I've bit the bullet and booked it into a main dealer to see if they can just diagnose the fault, they'll probably come back and say it's the EGR vavle now, goes in on tuesday, I'll keep you posted.

ScroobiusPip · Mar 15, 2012

wammers said:
How do you block the MAP sensor with a penny? The hole in it is only about 3mm. Do you mean the EGR feed pipe.

Sorry got my EGR valve and MAF sensor confused when typing!!

I've now deleted that post as it was pretty garbled!!

Saint.V8 · Mar 15, 2012

ScroobiusPip said:
Sorry got my EGR valve and MAF sensor confused when typing!!

I've now deleted that post as it was pretty garbled!!

Now try looking at the MAP sensor and associated little pipe for splits or blockages....as I mentioned previously.

ScroobiusPip · Mar 16, 2012

OK with the MAP disconnected I get more power, but the engine still suddenly dies on tick over, would it being disconnected cause this

. The pipe has no splits and isn't blocked, so I'm going to fit a new MAP sensor and EGR valve, as that was blocked off, and go from there.

ScroobiusPip · Mar 16, 2012

Hmmmm, just rang upa RR main dealer to be told the MAP sensor on that engine is obsulete and they can't get it any more!!! Think I'll try a different dealer or a BMW dealer.

ScroobiusPip · Mar 16, 2012

Out of interest has anyone got the correct part number for it, mine has 2244 674 on the top and is a BMW part, not surprisingly, but one dealer has told me the part number is 2246 084, this is the obsolete one!!

Datatek · Mar 16, 2012

ScroobiusPip said:
Out of interest has anyone got the correct part number for it, mine has 2244 674 on the top and is a BMW part, not surprisingly, but one dealer has told me the part number is 2246 084, this is the obsolete one!!

Get the fault codes read or you are chasing rainbows. The MAP (as opposed to the MAF) sensor rarely fails.

ScroobiusPip · Mar 16, 2012

Datatek,
I've got no fault codes, that's the problem, nothing comes up on the diagnostics, had it in to 2 independant garages, no joy, and I've heard that the MAP sensor doesn't show up, hence the reson for me changing it.

Datatek · Mar 16, 2012

ScroobiusPip said:
Datatek,
I've got no fault codes, that's the problem, nothing comes up on the diagnostics, had it in to 2 independant garages, no joy, and I've heard that the MAP sensor doesn't show up, hence the reson for me changing it.

Pretty sure that the Manifold Absolute Pressure does show up on diagnostics, at least on Faultmate using live data

A Challenge To Mechanics

Member

Dyed-in-the-wool 100% RR Junkie

Member

Member

No longer with us, RIP

Member

No longer with us, RIP

Member

Member

Well-Known Member

No longer with us, RIP

Member

Member

Dyed-in-the-wool 100% RR Junkie

Member

Member

Member

Well-Known Member

Member

Well-Known Member

Similar threads