Freelander 1 rough at low revs

Hi, everyone, I wonder if anyone can help me, my 2005 diesel freelander td4 has done around 70k and I've owned it for a year now.
When I bought it it ran fine apart from a slight rattle (pinking) at low revs, anyway I bought all the bits and serviced it and noticed the plug on the sensor at the bag of the air filter (map?) was unplugged, I plugged it in and it ran like a bag of crap, no power and lumpy rough running, so I unplugged it again and great. a few months later the HP diesel pump went so I replaced it with a new one, not relevant, but worth mentioning. Anyway the other day I borrowed a pretty decent code reader and plugged it in, it showed a security system fault and a fault with the sensor, so I ordered a new map off ebay and fitted it today, it runs great over 2k rpm, and is noticeably quicker, but at lower revs it's useless, it reminds me of a petrol engine with a misfire, no power and wants to stall all the time, put it this way it took 3 attempts to reverse onto my drive!
I've cleaned the air temperature sensor, ( the one in the hose at the front of the engine) and tested it with a meter which according to what I've read should read between 2 and 3k ohms on a cold engine, it reads 2.5k ohms. Does anyone have any idea as to whats causing this now because I don't really want to go back to disconnecting the sensor again long term, I only left it this long as I was out of work and money was tight.

the plug on the sensor at the bag of the air filter (map?) was unplugged, I plugged it in and it ran like a bag of crap, no power and lumpy rough running, so I unplugged it again and great.

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sounds more like the 'maf' sensor .. and given it's meant to read 'back of air filter' i assume ..

and a fault with the sensor, so I ordered a new map off ebay and fitted it today, it runs great over 2k rpm, and is noticeably quicker, but at lower revs it's useless, it reminds me of a petrol engine with a misfire, no power and wants to stall all the time, put it this way it took 3 attempts to reverse onto my drive!

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well IF it's the 'maf' .. then .. el cheapo off ebay ?
suggest you use only the oem bosch maf

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hd3 said:

sounds more like the 'maf' sensor .. and given it's meant to read 'back of air filter' i assume ..



well IF it's the 'maf' .. then .. el cheapo off ebay ?
suggest you use only the oem bosch maf

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I,ve done a bit more reading and I'm thinking there were 2 faults, yes that sensor I replaced was faulty, because the fault now is different to the original fault, and after doing a bit of research I'm starting to suspect the loom between the hp fuel sensor and the ecm. what brought me to this conclusion was that after digging about on various forums I learned that if you disconnect the plug on the maf sensor the car defaults to a certain set of values and also disables the fuel economy system, so instead of varying the fuel for maximum economy it just runs at a default level. now this apparently, so I,ve been led to believe, also tends to disregard a lot of information from the fuel sensors, so, the logic being, the previous owner had the car when the fault developed, somebody told him to dis the maf, he did, and problem 'cured', only obviously it wasnt. so now after replacing the maf sensor, it's throwing up the other issue.
I'm sort of heading down this route simply because if the new maf wasn't correct I'd expect the fault to stay the same, have you any experience of this sensor loom fault?

.. have you any experience of this sensor loom fault?

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no .. not on my td4 ..
reading up on engine issues soon after i got mine
it were clear that factory ecu to hp rail sensor loom was / is prone to water ingress
i bought some 'contralube' and smeared it over the hp sensor plug 'n socket contacts
that were feb. 2012
haven't had any problems with it at all ..
( and i have seen water collect by the oil filler cap .. so h20 does get in there .. somehow )

LR do supply an upgraded loom 'n plug that addressed the water ingress issue
( there is a part no. somewhere within the forum pages .. try a search
( use 'harness' in the search.. instead of 'loom' ..

and .. the symptoms of a corroded plug - socket
or just plain dirty ..
are numerous - weird .. and can be a head scratcher to diagnose ( without a proper reader )
at least that's what 'rover-ron' wrote in one of his td4 'problems' articles
( from .. https://www.tuning-diesels.co.uk .. )

that hp sensor only uses small voltages .. 5v down to some millivolts
just a little bit of dirt or corrosion screws the sensor operation up

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hd3 said:

no .. not on my td4 ..
reading up on engine issues soon after i got mine
it were clear that factory ecu to hp rail sensor was / is prone to water ingress
i bought some 'contralube' and smeared it over the hp sensor plug 'n socket contacts
that were feb. 2012
haven't had any problems with it at all ..
( and i have seen water collect by the oil filler cap .. so h20 does get in there .. somehow )

LR do supply an upgraded loom 'n plug that addressed the water ingress issue
( there is a part no. somewhere within the forum pages .. try a search )

and .. the symptoms of a corroded plug - socket
or just plain dirty ..
are numerous - weird .. and can be a head scratcher to diagnose ( without a proper reader )
at least that's what 'rover-ron' wrote in one of his td4 'problems' articles
( from .. https://www.tuning-diesels.co.uk .. )

that hp sensor only uses small voltages .. 5v down to some millivolts
just a little bit of dirt or corrosion screws the sensor operation up

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Yes, that's what I was thinking, more likely to be corrosion on the connector than actual loom failure, we get the same thing on some of the stuff at work (industrial & railway spark) I've had a supplier of connectors recommended to me so I think I'll give them a bell tomorrow and see if I can get a new plug and just replace the old one, job done, cheers for the info regarding that, it's along the lines I was going, just wanted a second opinion, 2 heads being better than 1.

What MAF sensor did you fit ? was it a genuine Bosch one if not you have waisted your money, after market MAF are no good at all.

Arctic2 said:

What MAF sensor did you fit ? was it a genuine Bosch one if not you have waisted your money, after market MAF are no good at all.

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No it was an aftermarket one from fleabay, I didn't fancy paying well over a ton for one, what gets me is why do they sell them if they don't work? there wasn't any bad reviews on them which I find strange.