Range Rover P38 Sluggish / no power

Datatek said:

You can block the EGR with a coin, no need to buy a kit, or you can disable the vacuum pump that operates it. Lots of folks have done it and the early P38's had no EGR. Personally I still think that the MAF affects fuelling to give closer control for emissions rather than just affecting the EGR. If it's for the EGR it's an expensive way of doing it, the MAP sensor or a modified version of it could perhaps have done the same job since the EGR must be closed when the turbo is presurizing the manifold or half the boost would be going the wrong way down the EGR pipe to the exhaust which is probably why yours wasn't pulling too well.

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Not according to Rave Keith MAF is for EGR control only. If the MAF is duff the EGR could be open all the time. But fuelling maybe reduced if the ECU thinks the EGR is open because the MAF is knackered.

would a faulty Air flow meter or EGR show up on diagnostics?

still say it is maf and not egr, infact i would put money on it!
some of the very first egr maf equipped diesels i know had the maf to control egr as they still had mechanical injection pumps and manifold pressure sensor.
but when electronic pumps came in and ever tighter emission controls the maf played a bigger part as it controls fuel maps in the ecu by measuring the amount of air flow to how much fuel is required.
if it were only to control the egr valve by removing the vac pipe to it so it stays in the closed position it should then have performance restored.
another point i doubt very much it will have a manifold pressure sensor as per earlier range rovers as it is not needed the maf will measure air flow and thus adjust fuel as required. if the maf only controls egr then it would have to have a manifold pressure sensor to measure air in the manifold to adjust fuel.
still say it is a faulty maf and not an egr fault and the proof would be in the manifold pressure sensor if it has one or not!

and no faulty maf doesnt show up on diagnostics

6704nathan said:

still say it is maf and not egr, infact i would put money on it!
some of the very first egr maf equipped diesels i know had the maf to control egr as they still had mechanical injection pumps and manifold pressure sensor.
but when electronic pumps came in and ever tighter emission controls the maf played a bigger part as it controls fuel maps in the ecu by measuring the amount of air flow to how much fuel is required.
if it were only to control the egr valve by removing the vac pipe to it so it stays in the closed position it should then have performance restored.
another point i doubt very much it will have a manifold pressure sensor as per earlier range rovers as it is not needed the maf will measure air flow and thus adjust fuel as required. if the maf only controls egr then it would have to have a manifold pressure sensor to measure air in the manifold to adjust fuel.
still say it is a faulty maf and not an egr fault and the proof would be in the manifold pressure sensor if it has one or not!

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The M51 in the P38 is efectively mechanical injection with added electronic control and it does have a MAP sensor.

ok ta - will keep it all nice and standard get the air flow unit ---

Softtop2011, please keep me posted as to how you get on with this. As I say mine has exactly the same issue and the independent I have been using seem to think its an injector problem.
I would love to be able to turn up with it running right or at least better and tell them they were wrong,

Dave

wammers said:

Not according to Rave Keith MAF is for EGR control only. If the MAF is duff the EGR could be open all the time. But fuelling maybe reduced if the ECU thinks the EGR is open because the MAF is knackered.

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You are reading from a different hymn sheet to me Tony, my copy of RAVE states the following "The MAF sensor located in the air cleaner outlet pipe monitors the amount of air being drawn in to the inlet manifold. This data is used by the ECM to calculate the injected fuel volume the intake air temperature and the rate of EGR"
No way the bean counters at LR/BMW would fit an expensive MAF just to control the EGR. Tighter more accurate fuel control was necessary to meet the new emission standards of the time.

i know that effectively the m51 is still a mechanical pump with electronic control. my post about the first maf egr equipped vehicles having mechanical pumps and not electronic meant they had a throttle cable and not electronic control so the maf sole purpose was to control egr as fuelling couldnt be adjusted electronically.
but as pumps then had electronic control the maf could be used to measure airflow to adjust fuel via ecu and fuel mapping electronically.
as i said all along would put money on it being maf from experience 20 yrs in the motortrade and 5 yrs of those as foreman and diagnostic master tech!
now fixing trains pays better!

6704nathan said:

i know that effectively the m51 is still a mechanical pump with electronic control. my post about the first maf egr equipped vehicles having mechanical pumps and not electronic meant they had a throttle cable and not electronic control so the maf sole purpose was to control egr as fuelling couldnt be adjusted electronically.
but as pumps then had electronic control the maf could be used to measure airflow to adjust fuel via ecu and fuel mapping electronically.
as i said all along would put money on it being maf from experience 20 yrs in the motortrade and 5 yrs of those as foreman and diagnostic master tech!
now fixing trains pays better!

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The M51 Range Rover engine has never had a throttle cable it has always had EDC.

Datatek said:

You are reading from a different hymn sheet to me Tony, my copy of RAVE states the following "The MAF sensor located in the air cleaner outlet pipe monitors the amount of air being drawn in to the inlet manifold. This data is used by the ECM to calculate the injected fuel volume the intake air temperature and the rate of EGR"
No way the bean counters at LR/BMW would fit an expensive MAF just to control the EGR. Tighter more accurate fuel control was necessary to meet the new emission standards of the time.

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Read RAVE again Keith. Both the fuelling and emission control sections. The MAF does exactly the same as the AIT sensor did on the none EGR engine. It does nothing different. It just does it in a different way. But it does it BEFORE the EGR valve to control it. Diesel engines are notoriously dirty on cold start. The EGR valve recirculates hot exhaust gas back into the manifold to maintain an ideal combustion temperature when the engine is cold. Thereby minimising the emission of unburned fuel and noxious gases. The MAF or IAT sensor is but one of many sensors that work together to fuel the engine. The diesel MAF is not exaclty an expensive component when compared to the petrol version. If you can buy one that is.

well aware range rovers with the m51 never came with a throttle cable. i was merely describing how early egr equipped vehicles were in comparison to later set ups.
for example rover 220sdi with l series diesel engines had egr and maf and mechanical pump with throttle cable and no edc maf controlled egr
later rover 25 with l series diesel had electronically controlled injection pump and maf controls boost fuelling and egr.
this is just an example of what i was trying to say may be a rover engine but was fitted to gaylander so it is allmost a landrover comparison!!!

also dont think you have description of egr correct as it does not open at idle would make it idle like a bag of spanners also does not open under full throttle would make it flat as a pancake.
egr is there to reduce combustion temps to reduce nox emissions. nothing else.
it should only really open when cruising along at a steady speed. as i understand it anyway!

wammers said:

Read RAVE again Keith. Both the fuelling and emission control sections. The MAF does exactly the same as the AIT sensor did on the none EGR engine. It does nothing different. It just does it in a different way. But it does it BEFORE the EGR valve to control it. Diesel engines are notoriously dirty on cold start. The EGR valve recirculates hot exhaust gas back into the manifold to maintain an ideal combustion temperature when the engine is cold. Thereby minimising the emission of unburned fuel and noxious gases. The MAF or IAT sensor is but one of many sensors that work together to fuel the engine. The diesel MAF is not exaclty an expensive component when compared to the petrol version. If you can buy one that is.

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What I gave was a direct word for word quote from RAVE, if you read the fueling section it only mentions the EGR but refers you to the Emissions control section. I know how the EGR works and I know why it's there, sorry you believe what you like but the MAF, as stated in RAVE, also fine tunes fueling and unlike a petrol car a diesel will run OK without it, but the emissions will suffer as will fuel consumption. The reason it's covered in the emissions section rather than in the fueling sections is that by fine tuning the fueling it reduces emissions.

data i agree with you, apart from i think if i read what you have written correctly that a diesel will run ok with a faulty maf apart from emissions and fuel consumption?
never seen a diesel with a faulty maf that does run ok!

6704nathan said:

data i agree with you, apart from i think if i read what you have written correctly that a diesel will run ok with a faulty maf apart from emissions and fuel consumption?
never seen a diesel with a faulty maf that does run ok!

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Unplug a duff one and the engine does run better

but with a faulty maf slow no power or top end etc unplug it, ecu sets default value and runs better, new maf all is well power fuel economy etc
ahhh i think we can finally agree we are reading from the same page!!!!!:clap2:

The MAF is there to run the EGR. If there was no EGR it would not need a MAF. Simples.

When looking at the F/O/S airbag of Dopeys P38 (96 or 97 can't remember specifics) when finished we looked at each others cars....

His is immaculate BTW....!!

We both commented on the presence of the EGR and MAF on mine (1999) and the lack of both on his....

The Wammer is right, the MAF is only there to provide input for the EGR system to regulate the emissions that are dependant on incoming air density, temperature etc by introducing exhaust air into the induction system to reduce the emitted output....

Sorry to butt in, but I think i read something that the car only effectively "remaps" itself every few thousand miles? So doesn't that mean that u would not notice a difference if unplug/changing the MAF straight away? or am I thinking of something else??