TD5 Down On Power

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TomCa7

Member
Posts
20
Location
Nottinghamshire
Just wanted to see if anyone has experienced similar.

TD5 Automatic Discovery (1999) with 145000 miles on the clock and it seems down on power with no obvious cause.

Just had a new MAF and injector loom. Nanocom showing no faults. Just seems that when you put your foot down from about 2300rpm its go no 'get up and go'. It'll get there but slowly - as a result I am burning fuel at quite an impressive rate. Driven a similar Discovery (age, mileage and an automatic) and that one seemed to have bags more pull.

Just wondered if anyone had any advise/tips/tricks worth exploring to see if I get the TD5 back to the way it should run.
 
Lots of possible reasons, I would start with the simple fixes.
Did the D2 you compared performance against have a remapped ECU?
Is this a recent change or was this an issue before the MAF replacement?
Did you use a genuine LR MAF (circa £150) or an aftermarket one (circa £35)?
You might want to try disconnecting the MAF and seeing if the engine runs better in default mode, if so the new MAF may well be the issue. It could also be a faulty MAP, so worth pulling out the MAP sensor and cleaning off any oil.
Otherwise you need to get a diagnostic tool onto it and start checking DTCs and the live data. Assuming it shows healthy sensors, I would start by comparing MAF at 3000 rpm high load (a hill is useful) and MAP under the same conditions. MAF should be 600+ if the turbo is working properly, MAP should be atmospheric pressure (AAP reading) + about 230. If MAF is low check air filter for clogging and turbo for wear, if MAF is good but MAP is low, then the air is going somewhere so check turbo to intercooler to intake hoses for air leaks.
Other than that you could be looking at fueling - pump, filter, fuel pressure regulator, injectors etc.
 
Thanks for the details response - definitely given me a lot to move forward with.

The other Disco wasn't mapped so was a relatively fair comparison. i have just done fuel pump and filter so at least I can tick off a few things.
 
EGR has been blanked off, but I'll take the MAP out for a clean anyway.

I'd been reading about the wastegate - do you need to completely remove it to check it or can it be done in-situe?
 
You can do it in situ, grab the rod with a mole grips around the locknut, spray some wd40 to the turbo spigot and push the rod few times against the turbo(the valve's spring will pull it back each time),... or you can release the rod at the circlip and work easy with the port's arm... there are some youtube videos for that
 
Agree with all comments above. Did you throw away your old MAF? If not, a cheap check could be to put it back on! See how it goes, i.e. is it like it used to be? Sounds bonkers, but I also once replaced a not good MAF with a new one, made no difference at all, then recently replaced with a well expensive one, it transformed the performance, and the fuel consumption, which I had despaired of for 4 years. Si Click is right about cheap, and even not so cheap ones.
You changed it, performance went off...depends how much you believe in coincidence, (Changing the injector loom will not have harmed it.)
 
Stanleysteamer said:
Agree with all comments above. Did you throw away your old MAF? If not, a cheap check could be to put it back on! See how it goes, i.e. is it like it used to be? Sounds bonkers, but I also once replaced a not good MAF with a new one, made no difference at all, then recently replaced with a well expensive one, it transformed the performance, and the fuel consumption, which I had despaired of for 4 years. Si Click is right about cheap, and even not so cheap ones.
You changed it, performance went off...depends how much you believe in coincidence, (Changing the injector loom will not have harmed it.)
Click to expand...
Same in my case. I have changed my MAF two times and even all values seemed good, I was not satisfied with the result. Finally I bought a genuine one, better performance and fuel consumption (29-30mpg).
 
The OP's is Eu2 so the MAF is not so important, as long as it delivers an acceptable signal it's OK, the EU3 is extremely sensitive to the MAF input cos the IQ(injected quantity) is calculated mainly based on MAF/rpm input while on Eu2 is MAP/rpm based so in this case genuine MAP/IAT sensor is compulsory
 
Sierraferry, I am sure you are right about the differences between Eu2 and Eu3. But as is obvious from the other posters so far on this thread, personal experience would appear to show that a good MAF is important. and it is not always obvious what a good MAF is. Just buying a new one deffo doesn't guarantee anything as I and Berg have both experienced. I have posted this elsewhere, but I will repeat that a guy I know who runs a 4x4 garage, specialises in Land Rovers and won't touch any beyond D2, also races Land Rovers. And he says that MAFs are such weird things that he and his cronies try all sorts of MAFs on their motors until they find one that "feels " dead right. So maybe an "acceptable signal" is harder to get than we would all think.
I still think that, as that is the only thing OP changed that could affect his running, he should go back to it and follow advice given above.
 
sierrafery said:
The OP's is Eu2 so the MAF is not so important, as long as it delivers an acceptable signal it's OK, the EU3 is extremely sensitive to the MAF input cos the IQ(injected quantity) is calculated mainly based on MAF/rpm input while on Eu2 is MAP/rpm based so in this case genuine MAP/IAT sensor is compulsory
Click to expand...

Didn't know that. I've cleaned the MAP in my EU2 TD5 a couple of times, but it is the same one it had when I bought it. No idea if it is genuine or aftermarket; are there any markings that would tell me? On the one hand I am hopeful it will be aftermarket and I may be able to get an improvement in performance, OTOH I have just checked the prices of genuine items (MHK100600L) £300! Really! and I thought the genuine MAF was expensive.
Anyone know any cheaper sources?
 
Si Click said:
Didn't know that. I've cleaned the MAP in my EU2 TD5 a couple of times, but it is the same one it had when I bought it. No idea if it is genuine or aftermarket; are there any markings that would tell me? On the one hand I am hopeful it will be aftermarket and I may be able to get an improvement in performance, OTOH I have just checked the prices of genuine items (MHK100600L) £300! Really! and I thought the genuine MAF was expensive.
Anyone know any cheaper sources?
Click to expand...
I too cleaned my MAP loads of times which made no difference to my problem of poor fuel consumption. Changed the MAF, no improvement either, then a few months ago changed the MAF for one that cost £127 plus VAT, WHAT AN IMPROVEMENT!!!!!
 
Stanleysteamer said:
I too cleaned my MAP loads of times which made no difference to my problem of poor fuel consumption. Changed the MAF, no improvement either, then a few months ago changed the MAF for one that cost £127 plus VAT, WHAT AN IMPROVEMENT!!!!!
Click to expand...
what year Td5 you have though? and do you still have EGR? I SAY AGAIN: DONT COMPARE A EU3 WITH EU2 WHEN IT COMES TO MAF for EU2 the MAP/IAT is more important ... unless the EGR is still on
 
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i'm not sure if you can unless it has a LR logo... it definitely should be manufactured by Bosch but with the LR part number and the oring to be green on it... if it's some other brand then you know it's not genuine
 
sierrafery said:
what year Td5 you have though? and do you still have EGR? I SAY AGAIN: DONT COMPARE A EU3 WITH EU2 WHEN IT COMES TO MAF for EU2 the MAP/IAT is more important ... unless the EGR is still on
Click to expand...

Mine is a TD5 AUTOMATIC DISCOVERY 2000, exactly the same as OP's, so DEFINITELY Eu2, and I had the problem with the EGR on, so I took the EGR OFF AND I STILL HAD THE PROBLEM. UNTIL I CHANGED THE MAF FOR THE EXPENSIVE ONE. Believe me guys, I tried everything I could think of to try to reduce consumption. NOTHING worked until I changed the MAF for a top price one.

Sierrafery, I really am aware that you know more about electronics in your little finger than I know in my whole head, so this is not a dig. I am just relating to this guy who has had exactly the same problem as me, and BERG450. The original problem arose when he changed both the MAF and his injection harness. We are both in agreement that the problem is unlikely to be the injector harness. So, there is either a coincidental fault, i.e. a fault that turned up at exactly the same time, (maybe cause by some accidental action under the bonnet when changing both the MAF and the injection loom), OR it is the MAF, which is NAF. OR can you think of anything he could have done, while performing these two operations that could have made the ECU go silly? You are really convinced the problem could be the MAP, so could he have upset the MAP by something he did with the loom or the MAF?

TomCa7, can I suggest, that if you are unwilling to try someone else's, or your old MAF, that you at least have a jolly good look around the under bonnet area to see if something that you might have disturbed under the boonet is not the issue? Something not properly plugged in, something snagged, something trapped? Something cut, something dirty?

I do have to admit that the new MAF improved the engine response throughout the rev range so Sierraferry, what is your opinion on something that only affects performance and fuel consumption mid-range and upwards? As always, I bow to your superior knowledge.electronic.
 
I didnt say that the MAF doesnt affect the Eu2 too but not in such crytical way than on the Eu3 but the managemenst are well different and also it has more involvment when it comes to autos regardless of engine type... for a 100% well running engine with optimal consumption a genuine MAF is needed on both but on Eu2 the MAF can be ruled out very simple by unplugging it and drive it so cos the default is very cose to the well working MAF just the consumption can be a bit affected so if the Eu2 doesnt run much better with the MAF unplugged it's certainly not that

if we refer to driveability under more than half throttle it's about boost or fuelling
 
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sierrafery said:
I didnt say that the MAF doesnt affect the Eu2 too but not in such crytical way than on the Eu3 but the managemenst are well different and also it has more involvment when it comes to autos regardless of engine type... for a 100% well running engine with optimal consumption a genuine MAF is needed on both but on Eu2 the MAF can be ruled out very simple by unplugging it and drive it so cos the default is very cose to the well working MAF just the consumption can be a bit affected so if the Eu2 doesnt run much better with the MAF unplugged it's certainly not that

if we refer to driveability under more than half throttle it's about boost or fuelling
Click to expand...

So, as Si Click and you suggested, OP should unplug the MAF, if that doesn't prove it's the MAF, then we need to think about how he managed to do something else which caused the problem, at the same time as what he did with the MAF and the injection loom. Like unplugging something, trapping something, cutting something or somehow bu99ering up the ECU, fueling or boost, (as he has the problems above 2300 revs.)
Perhaps he stuffed the old loom and/or the old MAF in the tank! (Tom Ca7, I AM joking!)
 
sierrafery said:
i'm not sure if you can unless it has a LR logo... it definitely should be manufactured by Bosch but with the LR part number and the oring to be green on it... if it's some other brand then you know it's not genuine
Click to expand...
Bosch, made in Germany with green O ring, part number 0 281 002 205. Comes up as OEM circa £84
Good enough or worth consigning to spares and buying a genuine LR one?
 
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