right gents let see if this make a difference or clarifies a few of the points being made on here.
I managed to get off work a little earlier today so I made a be line for the Range Rover.
Disconnected the pipe from the EGR and disconnected the MAF. Off we went.
Instantly noticed the difference, wow what a transformation. I decided though to conduct a little test which would involve driving the same hill which is about 1 1/2 miles long twice.
The first time I did it was with both the EGR and MAF disconnected, as I said a real transformation.
Got back down to the bottom of the hill and reconnected the MAF but left the EGR disconnected. Bloody hell, I never new just over 2 tonnes could move that quickly!!! It flew up the hill.I was enjoying myself so much I carried on driving around for about 1/2 hour just loving the car taking in as many hills as I could find (quite easy down here in North Cornwall)
So, what does this mean to those of you in the know, MAF fine just a clogged or knackered EGR or MAF and EGR both knackered??
Sorry I'm not particurlarly mechanically minded but trying to learn. I can't wait to hear the outcome of this.

Dave
By the way Softop2011 I'm in the same boat as you, I have only owned my P38 for just over 6 weeks now and for 3 1/2 of those weeks it has been in the garage. Granted when I bought it I knew it needed the gearbox oil cooler pipes replacing I just hadn't banked on a new gearbox oil cooler because the pipes were corroded on. Having to have the gearbox taken out because the other end of the pipes had corroded onto the box. I knew I was in for new pads but not 4 new discs. New brake pipes that lurk up behind the fuel tank also replaced. All this on a vehicle with 90,000 miles and full service history.Oh yeah a new battery as well.
God love the P38.
 
davlyn sounds like you have a slightly different fault prob egr stuck open, both you and soft top have a similar prob but with different causes.
if yours runs fine with egr disconnected and maf connected then leave it that way! just blank the small vac pipe ie stick a screw in it.
will not cause any probs by running it disconnected except slight mpg and power increase ( over a working egr equipped vehicle) and more importantly better engine longevity and leaving the engine oil in better condition, as it is not having sooty exhaust particules deposited in it.
softop has removed and cleaned his so i assume it is free and working, and has tried egr disconnected maf connected and still gets low power. and yours is good power with egr disconnected and maf connected.
so surely this proves my point that faulty maf affects fuelling as it has on softops!
 
Thinking about this - surely a MAF pre-turbo will work fine, if it really is measuring the mass of air - as this will be the same in the inlet manifold too... so the MAF could be used to control fuelling. Temp and pressure of the air will change but mass cannot. Unless the air can escape somewhere e.g. via a wastegate but I don't think the M51 has one of those....

I think a lot of the problem comes from forgetting that fuel:air ratio in diesel is not critical unless operating close to the limit, unlike petrol where it needs to be maintained at all times. Diesel is in lean burn all of the time. At the limit, the challenge is to prevent excess fuelling for emissions purposes - so it is reasonable to say that the primary purpose of the MAF (and the IAT on non-EGR) is to control emissions! Most of the time, when max power (ie full throttle) is not being requested, surely all the EDC is doing is reading throttle position sensor and squirting an appropriate amount of fuel in, at an appropriate time.......?

Cheers,

Jerry
 
Davlyn said:
right gents let see if this make a difference or clarifies a few of the points being made on here.
I managed to get off work a little earlier today so I made a be line for the Range Rover.
Disconnected the pipe from the EGR and disconnected the MAF. Off we went.
Instantly noticed the difference, wow what a transformation. I decided though to conduct a little test which would involve driving the same hill which is about 1 1/2 miles long twice.
The first time I did it was with both the EGR and MAF disconnected, as I said a real transformation.
Got back down to the bottom of the hill and reconnected the MAF but left the EGR disconnected. Bloody hell, I never new just over 2 tonnes could move that quickly!!! It flew up the hill.I was enjoying myself so much I carried on driving around for about 1/2 hour just loving the car taking in as many hills as I could find (quite easy down here in North Cornwall)
So, what does this mean to those of you in the know, MAF fine just a clogged or knackered EGR or MAF and EGR both knackered??
Sorry I'm not particurlarly mechanically minded but trying to learn. I can't wait to hear the outcome of this.

.
Click to expand...

If it runs well with the MAF connected, either the MAF is totaly dead so making no difference or it's working correctly. If the performance is down with the EGR connected I would suspect the EGR valve is sticking, i.e. it opens on command but fails to close properly. Leave the EGR disconnected or take it apart and clean it.
 
Davlyn said:
"What?" the suspense is killing me!!
Click to expand...


Think maybe you should be looking at EGR modulator. Or just leave it disconnected. If it fails it has two modes fully shut or fully open. Fully open is not what you want. Seems to me from your little experiment that that is the case. With MAF and EGR disconnected engine is running on ECM defaults. Interesting to note that it was better with just MAF connected, this means it was actually introducing more fuel than the standard map. Food for thought maybe considereing all that has preceded this.
 
wammers said:
Think maybe you should be looking at EGR modulator. Or just leave it disconnected. If it fails it has two modes fully shut or fully open. Fully open is not what you want. Seems to me from your little experiment that that is the case. With MAF and EGR disconnected engine is running on ECM defaults. Interesting to note that it was better with just MAF connected, this means it was actually introducing more fuel than the standard map. Food for thought maybe considereing all that has preceded this.
Click to expand...

Could still be the MAF is faulty in a mode that fools the EDC into overfueling. I agree about the modulator valve though. Be interesting to look at what is going on using live data.
 
I think this is a great thread, nobody being a tit and spitting the dummy out, good shared knowlege, that to me is what a forum should be about unlike some that was on here about a year ago who thought that being an arse and abusive was being smart (unless it's deserved of course)
Davie :D
 
Hi all - its arrived - the dreaded replacement maf unit - fitted the unit with trepidation plugged it in checked all the other bits were in place - fired the old girl up and let her idle - seemed fine - selected drive pulled off and :D :D:D:D all working fine power there when you pull off and still goes like it should not a racing car but loads better than when the old maff unit was plugged in - BIG THANKS to you all for your advice and comments on this ....
 
Evening all,
Sorry to restart this thread but I have a quick question for you guys.
After concluding that the EGR was knackered somebody suggested blocking the vacuum pipe off. Now this is going to sound like a really stupid question but which end of the pipe should I block off? Before you all **** your side laughing I just can't get my read round which end should be capped. Should I leave the pipe on the EGR and disconnect it at the other end and cap it or leave it on the thingy ma jig and cap the end that came off the EGR or am I worrying about nothing and just cap either end?

Dave
 
Davlyn said:
Evening all,
Sorry to restart this thread but I have a quick question for you guys.
After concluding that the EGR was knackered somebody suggested blocking the vacuum pipe off. Now this is going to sound like a really stupid question but which end of the pipe should I block off? Before you all **** your side laughing I just can't get my read round which end should be capped. Should I leave the pipe on the EGR and disconnect it at the other end and cap it or leave it on the thingy ma jig and cap the end that came off the EGR or am I worrying about nothing and just cap either end?

Dave
Click to expand...

Remove the pipe from the EGR valve and block that. You can actually push a suitable blocker in then reconnect it so it looks connected.
 
Just trying to understand this, but if there is a failure on the EGR system or the MAFF system why are there no faults shown on the dash, or at least a seek help from the dealer instruction.
 
johnmowcop said:
Just trying to understand this, but if there is a failure on the EGR system or the MAFF system why are there no faults shown on the dash, or at least a seek help from the dealer instruction.
Click to expand...

The ECU has no idea whether or not the EGR responds to commands so cannot report a failure, as for the MAF, I have yet to see a car where a MAF failure is reported by the Engine ECU:)
On some Transits, there is feedback from the EGR to show it has operated and disconnecting it causes a fault to be logged:eek:
 
Datatek said:
The ECU has no idea whether or not the EGR responds to commands so cannot report a failure, as for the MAF, I have yet to see a car where a MAF failure is reported by the Engine ECU:)
On some Transits, there is feedback from the EGR to show it has operated and disconnecting it causes a fault to be logged:eek:
Click to expand...

It should know if EGR is opening or not because the MAF airflow will change. The MAF air flow measurement is then used by the ECU to modulate the EGR valve to control the amount of exhaust gas allowed in.
 
wammers said:
It should know if EGR is opening or not because the MAF airflow will change. The MAF air flow measurement is then used by the ECU to modulate the EGR valve to control the amount of exhaust gas allowed in.
Click to expand...

True, but if the EGR fails to open on command, the system is unaware as evidenced by the fact that you can block the vacuum pipe and no fault is reported. Do that on the Transit and it logs a fault and eventually goes into limp mode.
 
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