Disco TD5 AAP - ambient air pressure sensor question

Hi all

Just have a question about the AAP in the air filter box, at some point it changed from a 3 pin (MHK100600) to a 4 pin(MHK100820), does anyone know what year this happened, and can you change a 3pin to a 4 pin if you run an extra wire to the ECU. I'm asking because the 100600 is approximately £200 to buy and the 100820 is £90 form the stealership, or if you go to BMW and order a part number 0872648 for a mini it's the same as a 100820 but is only £34

solly619 said:

Hi all

Just have a question about the AAP in the air filter box, at some point it changed from a 3 pin (MHK100600) to a 4 pin(MHK100820), does anyone know what year this happened, and can you change a 3pin to a 4 pin if you run an extra wire to the ECU. I'm asking because the 100600 is approximately £200 to buy and the 100820 is £90 form the stealership, or if you go to BMW and order a part number 0872648 for a mini it's the same as a 100820 but is only £34

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Hi,
MHK100820 is for VIN YA711531 on, so after 2000 .... u better search the proper part number for your VIN with Microcat cos i dont think it's good to play with inputs and outputs of these sensors, MHK100600 doesnt even look the same as i saw on ebay...The AAP sensor could mess up the turbo boost controll so IMO u better use the dedicated one.

According to the sites I've just visited MHK100600 the MAP sensor, but you were talking about replacing the AAP airfilter box sensor.

Which is it you want/need to replace?

thebiglad said:

According to the sites I've just visited MHK100600 the MAP sensor, but you were talking about replacing the AAP airfilter box sensor.

Which is it you want/need to replace?

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So it is with the MHK100820 too, on some sites is MAP, on others AAP, there is even for aircon on one site ...that's why i thought Microcat is the way to sort this out....here they say that MHK100600 is on the airbox so it should be AAP but it definetly looks like the MAP Land rover td5 air temperature sensor MHK100600 on eBay (end time 20-Dec-10 12:41:55 GMT)

sierrafery said:

So it is with the MHK100820 too, on some sites is MAP, on others AAP, there is even for aircon on one site ...that's why i thought Microcat is the way to sort this out....here they say that MHK100600 is on the airbox so it should be AAP but it definetly looks like the MAP Land rover td5 air temperature sensor MHK100600 on eBay (end time 20-Dec-10 12:41:55 GMT)

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In that case perhaps they used the same component on both applications??

I'm just firing up my version (aug 2009) of Microcat to see what it says.

Ok according to my version of Microcat the part number for MAP all years is MHK100640 with a retail price of £40.41+vat

It couldn't find MHK100600, or MHK100820 at all.

Did find MHK100600L (£176.17+vat) and MKH100820L (£68;54+vat) but both of these are listed as "Sensor - AMBIENT AUTOMATIC AIR CONDITIONING" These are the sensors on the airfilter box.

Just been out to check my car ('99 TD5 auto non-aircon) and it does still have this sensor on the airbox.

thebiglad said:

Did find MHK100600L (£176.17+vat) and MKH100820L (£68;54+vat) but both of these are listed as "Sensor - AMBIENT AUTOMATIC AIR CONDITIONING" These are the sensors on the airfilter box.

Just been out to check my car ('99 TD5 auto non-aircon) and it does still have this sensor on the airbox.

Click to expand...

In this case they made a mistake by naming them ".............AIR CONDITIONING" cos the sensor on the airbox is AAP without any doubt and it has nothing to do with the aircon.

sierrafery said:

In this case they made a mistake by naming them ".............AIR CONDITIONING" cos the sensor on the airbox is AAP without any doubt and it has nothing to do with the aircon.

Click to expand...

Unless it is used as part of the aircon control circuitry in addition to it's AAP function?

thebiglad said:

Unless it is used as part of the aircon control circuitry in addition to it's AAP function?

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No way biglad....unless all the diagrams and the whole operation mode of the Disco 2 systems in RAVE are fallacious.

As u see u have one on your non aircon car. According to RAVE this sensor's signals are used by the ECM:
l To maintain manifold boost pressure.
l To reduce exhaust smoke emissions while driving at high altitude.
l Control of the EGR system.
l Exhaust gas over temperature protection.
l Turbocharger overspeed protection.

Hi chaps, thanks for the post so far, maybe I should give a little more info as this seems a hot topic,

I have a 2000 TD5 auto with aircon, and i have change the ECU to a programmable one out of a 2003 year disco which as a autologic tune on it (put in and programmed by my local land rover indy) and I noticed when I was looking at rave that there was a difference with the AAP set up between a 2000 and 2003 model i.e 1wire going to pin 31, i also got hold of a 2003 air filter box lid which had the MHK 100820 AAP on it so decided to plumb it in to see if it would cure the fault codes I was having on my hawkeye, so far I can not tell because the sensor I have is not reading correctly, so have brought a new one from BMW as it's the same for a mini (see previous post) I figured that if I have an ECU from a 2003 disco it will need a AAP form the same, as it as been on testbook and logitec diags systems and both say the AAP is not working (but not on hawkeye, been in touch with them but not give any satisfactory reply) yet when I put the original ECU back on it works fine with no faults... So that's why I was asking the question

im sure that fault code is related to oil in the wiring harness, check it out of you havent already

if not why not just bag a used sensor?

There was oil in the loom, so have cleaned that and took the orange rubber out same time I did the injector loom, so that not a problem now, and a new sensor only cost a tenner plus postage off fleabay, so was cheaper than a second hand one ( my local rover spares man want £15 + vat, and at least this was I'll know if it's working correctly....I hope

solly619 said:

Hi chaps, thanks for the post so far, maybe I should give a little more info as this seems a hot topic,

I have a 2000 TD5 auto with aircon, and i have change the ECU to a programmable one out of a 2003 year disco which as a autologic tune on it (put in and programmed by my local land rover indy) and I noticed when

Click to expand...

Here is where your problem begins....i saw several cases myself when this swap didnt totally succeed ......................and i wasnt alone see this carefully Web Rover

Thanks sierrafery interesting site, but I was told that once reprogrammed it wouldn't make a difference, apart for the hawkeye codes, which I'm hope will be cleared when I fit the newb AAP, I don't have any prolems running it except I'm not getting the milage was expecting... But if that don't work I may have a tuned ECU for sale, so I can send mine off to TD5 alive for a remap.....

solly619 said:

apart for the hawkeye codes, which I'm hope will be cleared when I fit the newb AAP, I don't have any problems running it except I'm not getting the milage was expecting..

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That's strange m8, that u have fault codes on the AAP and the car is running fine(which it shouldnt), coz >>
"In the event of an AAP sensor signal failure any of the following symptoms may be observed:
l Altitude compensation inoperative (engine will produce black smoke).
l Active boost control inoperative.
l Turbocharger boost pressure limited to 1 bar (14.5 lbf.in 2 ).
l EGR altitude compensation inoperative."

Never had a problem, Apart from codes 3018 coolant temp high fault logged, 3034 coolant temp fault active, 3174 fault detected with auto box which is recorded on hawk eye and ambient air temp sensor fault on test book and autologic, I did read once that some had these codes before and it turned out to be the AAP not plug in

Update

I have changed my 3 pin AAP for a 4 pin one which is on models from 2003, I have now cleared all fault codes, so i can conclude that if you have a pre 2003 disco and you change your ECU for a post 2003 reprogrammable one you should have a post 2003 AAP, but you need to wire in the fouth pin, which goes to pin 31 on the red block in to the ECU, you will also need the top of the air box as well because the fit is different, you can also get the multi pug from a rover 25, 400 or 75, it comes off the injector loom, the MAP sensor, as it's called on rover cars, is also the same as the post 2003 AAP on a disco.... At last

noticed any change in performance or economy?

Yes, gone from averaging 23/24 to 27 on my work run and 31/32 when I go back to derby and that with AT2 all terrains on, just doing a little experiment now by putting some 80/20 continentals on to see if that makes a difference as just about all my driving is on road now I have to travel further for work, if there's not much difference my AT's are going back on, they look much better

is it worth trying the green top injectors as the software its running is designed for the higher pressure. i did try some in a 10p engine once but had the early software. just a thought?