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Td5 issue MAF?


PITBULL

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Having a issue with my newly purchased td5 where when full throttle in 3rd about 3,500Rpm it loses power. Now it’s happened a few times so to try working out what’s happening while accelerating hard through the gears I change before 3,500rpm but then it happened in 4th? The problems continues as now it’s got no power for about 15-20 seconds on start up (even if it’s been running and turned off the straight back on) now I think I’ve narrowed the start one to the MAF sensor as when I disconnected it it made no difference so ordered a new one. But I’m worried that the lose of power on a long pull possibly caused the MAF failure? Anybody have any ideas what the issue could be?

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MAF's do get dirty and then go out of range causing a 'defaultsetting to kick in, if it is that then a new one will solve it. Some people go to the trouble of cleaning the original but it is delicate work. I think it is unlikely that your booting it caused the issue,... much more likely just made it more obvious. I take it you are confident of fuel supply , it would be the obvious other  cause?

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I’ve replaced the the MAF sensor now and it’s fixed the lack of power for the 1st 15-20 seconds. But the thing I’m worried about is the loss of power when full throttle for a period of time? When it happened first time it was going up hill and it was like it hit a limiter. But then when trying again on a flat it done it again but was still accelerating, so it was obvious it wasn’t a limiter? I’m worried to try now incase it damages the new MAF but I can’t see how it would but it was after that happening a few times the loss of power at start started 🤷‍♂️

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MAF can only be damaged AFAIK by debris through the air intake, .... so long as your filter is in place and in good nick that won't be a concern.  At this stage it might be helpful to find someone with a Nanocom or similar to see what errors if any are present,. My bet would be that your driving style has stirred up 20 odd years of carp and started to try and push it through the fuel system, old school basics will help eliminate causes. There may be a flow test you can do under the bonnet, I have never needed to but someone on here may have the detail or check out Rave. For myself I would start with the in tank  pre-filter, check the tank, blow through the supply and return lines, check / replace the main filter, and just satisfy myself that the system is clean and bright. Remember if it had been standing a while that modern diesel is susceptible to bug growth which is a killer in the small lines and filters, particularly if the tank was near empty and there was lots of moist farmyard air in there as well. HTiSH

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Thanks for your time to try helping. It puts my mind at rest a bit about the damage to the MAF. I’ve just replaced the fuel filter but will have a look through the rest of the fuel system to make sure it’s all ok 👍 

Edited by PITBULL
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I've seen more than one TD5 MAF damaged by K&N type (oiled) air filters, the oil mists up and coats the sensor element.

That said, TD5 owners do seem to get through a lot of MAFs in general, maybe they're just a poor design. I know some of them carry a new one as a spare.

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On 8/7/2020 at 11:07 AM, FridgeFreezer said:

That said, TD5 owners do seem to get through a lot of MAFs in general, maybe they're just a poor design. I know some of them carry a new one as a spare.

They have the reputation of being either good or carp.

Apropos filters, there is a tiny filter screen under the fuel pressure regulator on the rear of the head, right side that could be gummed up.

Item 13...

Td5 fuel diagram - Defender Forum (1983 - 2016) - LR4x4 - The Land ...

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What you describe seems more like overboost not MAF related  especially if with it unplugged made no difference.. check the pipework connected to the wastegate modulator and if nothing obvious remove fuse F2 engine bay and make a drive test then... if the symptom goes away replace the wastegate modulator, if no change use a pump on the wastegate valve to see if it works or not also make sure it's not stuck

Edited by sierrafery
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13 hours ago, sierrafery said:

What you describe seems more like overboost not MAF related  especially if with it unplugged made no difference.. check the pipework connected to the wastegate modulator and if nothing obvious remove fuse F2 engine bay and make a drive test then... if the symptom goes away replace the wastegate modulator, if no change use a pump on the wastegate valve to see if it works or not also make sure it's not stuck

The loss of power was solved by the MAF sensor but I haven’t done a hard pull in it since as I am a bit worried it’ll damage the new MAF sensor 😳 but I thought it might be overboost. I’ll have a look at all the pipe work tomorrow. 

 

On 8/7/2020 at 10:07 AM, FridgeFreezer said:

I've seen more than one TD5 MAF damaged by K&N type (oiled) air filters, the oil mists up and coats the sensor element.

That said, TD5 owners do seem to get through a lot of MAFs in general, maybe they're just a poor design. I know some of them carry a new one as a spare.

It has a K&N air filter on it 😳 

not sure if it’s oiled or not? 🤔

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Cutting out under hard load can be due to a stuck wastegate. If the MAP gets too high, the ECU will cut fuel to prevent boost from rising further. As said, make sure the wastegate is operating as it should and adjust if necessary.

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