Disco 2 A MAF problem, or not?.

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Big Phil

Big Phil

Active Member
Posts
176
Location
Sheffield
Took my recently acquired Disco 2 Td5 2004 for a service this morning. On collection this evening, all well, except the mechanic tells me the MAF is disconnected. When connected and taken on a test run, Disco runs sick, no throttle low revs, into limp mode. Disconnect and it goes ok again. Now he thinks the MAF is working ok after testing it, but on searching the web all information points to a faulty MAF sensor. There are no lights on the dash like the three amigos or anything else.

The limp mode (no lights on dash) has occurred a couple of times before todays service, usually after starting up first thing in the morning, and by the time I reach the main road, 4/5 hundred yards it has cleared and it's running ok. I wish it would enter limp mode and not resolve itself, then my mechanic would have a better chance of diagnosing the fault I think.

On reflection I have started the engine once when two flashing green lights came on, but on turning the key off and restarting the engine they disappeared.

Can anyone put a finger on what may be causing the limp mode. Any help would be most appreciated. I'm a little worried about having the caravan on the back on the motorway and the Disco going into limp mode.

Thank You.
 
Do the sport and manual green lights light up on systems check when you turn on ignition.
Have the fault codes in the automatic transmission read to see if there are any present, clear them then have reread after you experience limp mode again to see which are current as opposed to historic.
According to rave limp mode should trigger flashing sport manual green lights so are you sure you are experiencing limp mode, fourth gear if you are moving, third gear from standing start.
If you know of someone who has a nanocom you could record live data when driving with maf connected, post results on here and someone will be able to analyse results.
From my own experience of faulty maf it contributed to poor running but did not trigger limp mode.
 
For the Eu3 engines(like your's is) a well working MAF is very important, only genuine are reliable so dont go cheap on it, with MAF unplugged the ECU's addaptive strategy needs a certain time to go to default to MAP reading that's why it starts running better after a short drive, especially if EGR is still present and as it affects the throttle response it can mix up the autobox management via the CAN... first of all fit a new genuine MAF to be ruled out and if you still have EGR clean the valve inside and the MAP sensor cos i'm sure it's full of gunk....there is EGR cleaner spray on the market but you can use carb cleaner too

another thing to check is to not be oil in the ECU red plug cos if it is you must replace the injector loom and keep cleaning the plug once a week untill all the oil leaves the harness

for the flashing M+S on start up which are reset by ignition a weak battery or charging issues are the most common
 
Last edited:
ROY SIMPSON said:
Do the sport and manual green lights light up on systems check when you turn on ignition.
Have the fault codes in the automatic transmission read to see if there are any present, clear them then have reread after you experience limp mode again to see which are current as opposed to historic.
According to rave limp mode should trigger flashing sport manual green lights so are you sure you are experiencing limp mode, fourth gear if you are moving, third gear from standing start.
If you know of someone who has a nanocom you could record live data when driving with maf connected, post results on here and someone will be able to analyse results.
From my own experience of faulty maf it contributed to poor running but did not trigger limp mode.
Click to expand...


Thanks for the prompt reply Roy. The sport /manual green lights do appear when the ignition is turned on, and go off with the rest of the system check lights.
I will try to get the nanocom readings done, the only problem been waiting for the "limp mode" to occur again as it comes and goes infrequently, it's not an every day occurrence.
Regarding the third gear start and fourth gear running, it does neither of these. From a starting position on our drive, it runs sweetly engine wise, other than it will not rev, and as stated it does pick up the revs before I get to the main road, then it runs fine.
Regarding the maf, I will swap it out for another to see if it makes a difference. I really wish when it enters "limp mode" it would stop like that, then we could probably bottom the problem.
Thank you for your input, it is most appreciated.
 
sierrafery said:
For the Eu3 engines(like your's is) a well working MAF is very important, only genuine are reliable so dont go cheap on it, with MAF unplugged the ECU's addaptive strategy needs a certain time to go to default to MAP reading that's why it starts running better after a short drive, especially if EGR is still present and as it affects the throttle response it can mix up the autobox management via the CAN... first of all fit a new genuine MAF to be ruled out and if you still have EGR clean the valve inside and the MAP sensor cos i'm sure it's full of gunk....there is EGR cleaner spray on the market but you can use carb cleaner too

another thing to check is to not be oil in the ECU red plug cos if it is you must replace the injector loom and keep cleaning the plug once a week untill all the oil leaves the harness

for the flashing M+S on start up which are reset by ignition a weak battery or charging issues are the most common
Click to expand...

Thank you for the prompt reply sierrafery. As stated above I will swap the MAF out first job, hopefully it would be a relatively cheap fix. Regarding the EGR, as I write this the replacemant sits on my coffee table waiting to be fitted. I will examine the MAP sensor and ECU red plug for contaminants.
Regarding the m/s flashing after start up. it has only done it once, and restarting the engine "solved" the problem, hopefully.
Thank you for your advice, it is most appreciated.
 
Big Phil said:
I will swap the MAF out first job, hopefully it would be a relatively cheap fix.
Click to expand...
welcome... though it will not be cheap if you buy genuine LR which is the only 100% reliable, if you'll find it too expensive then go for the cheaper Siemens/VDO which at least is made by the OEM but not at so high quality like those made for LR. buying any other brand for an Eu3 engine is wasted money and might not help much or will not last.
 
From your description of symptoms you are not experiencing limp mode as described in rave and do not have a problem with automatic transmission.
From your description you have similar problems to one's I had, started ok, ran ok up to 30 mph, slow rough running up to 50 mph with heavy acceleration, after which seemed to run ok again but symptoms returned when slowing below 50 mph. which I cured by replacing map and maf sensors.
I used the Siemens vdo maf sensor and the car runs very well but dropped about 2 mpg.
I would do as sierrafery suggests as your problem is engine management.
My disco is a 2002 auto with 15 p engine with egr fitted.
 
ROY SIMPSON said:
From your description of symptoms you are not experiencing limp mode as described in rave and do not have a problem with automatic transmission.
From your description you have similar problems to one's I had, started ok, ran ok up to 30 mph, slow rough running up to 50 mph with heavy acceleration, after which seemed to run ok again but symptoms returned when slowing below 50 mph. which I cured by replacing map and maf sensors.
I used the Siemens vdo maf sensor and the car runs very well but dropped about 2 mpg.
I would do as sierrafery suggests as your problem is engine management.
My disco is a 2002 auto with 15 p engine with egr fitted.
Click to expand...

Thank You very much for posting Roy, I appreciate your and others help. I will follow the advice given and see what happens, if I find the "fix" I will post on here as it may help others.
Been down to my local independent LR garage this morning to see if they had a genuine MAF on the shelf, no new ones but several "used" ones. Going back on Wednesday next week as the "electric mechanic" is on holiday until then, give them time to order a new MAF. I think I may get them to fit my EGR kit while the Disco is there as well, at 68 and registered disabled only the very easy jobs get done by me these days.
Thanks again chaps for the help. I will report back after having the new MAF and EGR fitted.
 
Have to wait while next Tuesday to have the work done, as there is a backlog of jobs after the mechanics holiday. Starting with a new MAF and EGR removal. I am a little worried as he mentioned the xyz switch in the conversation regarding the two green M&S dash lights. I sense my new purchase may cost a few bob to put right. Wish the Government would put my pension up, but I will not hold my breath on that happening.
 
Just been on the net surfing around this afternoon and found a clip on you tube on checking the MAF. Only 3 wires, one at battery power 12v, center wire from ECU, third wire earth from ECU. First wire shows 12v as it should, but centre ECU wire which should show 1.9v with key on and 3v with engine running shows nothing. Any ideas anyone. I have tried the net but it's been no help.
 
I was just looking to see if the MAF was in a working condition before l dropped the Disco off this morning.
When I got to the garage this morning it had been broken Into during the night.The majority of the survey Lance cameras were disabled and the electricity coming into the building was targeted and disabled. So that had to be sorted before any work could commence.
Anyhow, EGR removed which has made a difference to the performance for sure. Back in the morning when the new MAF has been delivered to complete the job. Then who to contact for the stage one chip is the next job.
 
All ok now, booked in next Monday at Alive Tuning, then back home to pick up her indoors and the caravan then off to North Yorks for 10 days. First trip with the Disco, hope all goes well. Thanks for the help Gentlemen. Much appreciated.
 
Update as promised. Just back from the 10 day tour of the Yorkshire Dales with the caravan in tow.
Since having the EGR removed and the new MAF and Alive Tuning the Disco has not missed a beat. No twin green lights on, no loss of power in any way, no warning lights on the dash of any description.
Before the work was done, MPG had been as low as 14 to the gallon. Touring around the Dales (nice and steady) it has risen to 28 to the gallon. Dragging the van behind 18/20 miles per gallon. I think we can call it - job done.
Thanks to all who posted to help me. Much appreciated.

ps, the modest tune from Alive has transformed the driveability of the Disco.

pps, we went over the hardknott pass, and onto the winrose pass where I expirienced brake fade, even though selecting 2nd gear and in places 1st gear on the auto box. We gave it a rest to cool off while we had a coffee and the brakes had returned to normal when we resumed our journey. Good job I had 30 years of trucking to fall back on re the brakes.
 
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