drives nicely with occasional boost of power!?

Hello all,
I'm looking for some advice, my 2004 TD5 defender has a slight issue i've been trying to pin down for a few weeks although the issue has been going for a while.

simply put, the engine starts, runs, drives etc. perfectly, I would never assume anything was wrong, it pulls well. it will be like this for weeks at a time, then all of a sudden I'll appear to gain what feels like 20hp! it will pull very noticeably better through all gears.
at first I though it was me, some days i'd have a heavier foot but recently i've been testing it.
when 'normal', flooring it from 50-60mph in 5th gear will take around 7 seconds. then when I can feel the extra power it will take 5 seconds. this test has been repeated many times with the same results.
today, pulling off hard in first (from idle) no chance of wheel spin, when i have the extra power the wheels will spin relatively easily.

I don't understand how something can be so intermittent. the only common denominator is I was pulling off a large roundabout in 3rd, then i could feel it, a sudden surge of power and there it was, then for the rest of the journey i had the extra power. I stopped, turned off the engine for 2 mins, continued, still with the extra power. then after 4-5mins, pulling off a roundabout in 3rd again, I felt the power drop off and the rest of the journey was back to 'normal'.

I would say the difference between 'normal' and extra power is as night and day as stock vs stage 1 remap.
the vehicle has a stage 1 remap, with EGR delete and no centre box, it still has a CAT.

things i've checked so far:
clutch switch
ECU for oil, nothing noteworthy.
various connections in engine bay.
next step if cleaning sensors and finding someone with a namocom or similar.

any ideas?
many thanks,
Callum

Fuel filter, air filter, collapsing intercooler hose ??

Oil in injector harness, sticky turbo wastegate, shìt remap?

fuel and air filter changed recently, hoses look good from the outside, I will check them fully as i know they can delaminate.
injector harness changed recently, will check wastegate tomorrow. I don't think the map is the issue as it was done by a very well known and reputable company, that said, i haven't ruled it out and i have contacted them.

I found some good vs bad maf resistance figures and just checked mine, it matched the bad maf figures so i may be onto something. Is it possible for a maf sensor to go bad and occasionally have bursts of life?

many thanks,
Callum

Drive it with the maf unplugged, if it feels better there’s your issue.

Do you have access to a Nanocom or similar?

tom1979 said:

Do you have access to a Nanocom or similar?

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unfortunately not, I saw you can rent them for a week from ebay, I might give that a go if its not the MAF

It will most probably be your Maf

went for a drive today with the maf plugged in, 'normal' performance, as expected.
when I unplugged it there it was, a huge difference! so i'll order a new one from eurocar parts and collect on monday.
am i right in thinking without the maf plugged in I'll be running on default values? so a new maf should give even better performance?

many thanks all,
Callum

Yep it'll run on default strategy.

Are you getting a genuine LR one? Everyone says you must have LR but I fitted a siemens/vdo to my disco 2 and it was fine as far as I know but I'd probably get genuine tbf

1988smithy said:

Yep it'll run on default strategy.

Are you getting a genuine LR one? Everyone says you must have LR but I fitted a siemens/vdo to my disco 2 and it was fine as far as I know but I'd probably get genuine tbf

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the one i can get on monday is by a company called HAAS, I'll look at genuine though, shouldn't be too much price difference (hopefully!)

C.McGrory said:

the one i can get on monday is by a company called HAAS, I'll look at genuine though, shouldn't be too much price difference (hopefully!)

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They're extortionatly expensive

1988smithy said:

They're extortionatly expensive

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ah yes, i've just seen them @ £150 haha
I think i'll give the cheaper one a go first!

Better drive with MAF unplugged than with aftermarket cos it can mix up the management as theyr's reading curve is rarely the best

C.McGrory said:

ah yes, i've just seen them @ £150 haha
I think i'll give the cheaper one a go first!

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For a MAF?? Siemens VDO is about £80-£90, sometimes less

tom1979 said:

For a MAF?? Siemens VDO is about £80-£90, sometimes less

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that's OEM, also aftermarket made by the manufacturer of the genuine LR at lower quatity, the MAF is too important for the Eu3 engine management to mess with pattern parts

sierrafery said:

that's OEM, also aftermarket made by the manufacturer of the genuine LR at lower quatity, the MAF is too important for the Eu3 engine management to mess with pattern parts

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I’ve never had a problem with VDO, and neither have you by the looks of it

sierrafery said:

if your's is de-EGR'd it might make no difference with unplugged MAF as long as the fuel consumption is good and no black smoke, i observed that early non remapped manual modells have a fuel map in which the MAF's involvement in fueling is quite reduced or none at all as the MAF readings are used mainly for EGR management, i made all kind of tests with my 2000 manual on the original chip, MAF unplugged , good VDO MAF, BMW MAF, bypassed signal with TP sensor input and the engine running and fuel consumption was the same no matter in which configuration... though there are autos and latest modells which can be sensitive to lack of good MAF input, couldn't work out a clear pattern but that's my general conclusion

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sierrafery said:

in the CSV format it's hard to figure out things, open an excell page import the CSV file then put ; as delimiter, or open the file with excell, highlight the whole data, select ''text to columns'' and use the delimiter. then you get .xlsx format
i converted only one and it's enough for me to say that your MAF is fubar'd, did you try to see how it goes with it unplugged? ... it's clearely visible that the idle reading is too low (41) should be between 55-60 and the reading under load beetween pos 28 -34 is around 330 and should be between 600-650 there, unplug the MAF and drive it so cos i have the feeling it will run OK untill you buy a new one...get VDO only, if you still have EGR at least clean it but better bypass it...keep cleaning the red plug once a week untill all the oil leaves the harness

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sierrafery said:

That doesnt look good to me.... fact is that if the engine runs better with it unplugged it's certain that you need a new one and better not put one at all than some cheap sh*T, VDO is the only correct way to go

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tom1979 said:

I’ve never had a problem with VDO, and neither have you by the looks of it

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Fookin ell inspector closeau!

I don't see a problem with a decent siemens/vdo, as I said i fitted one to my old disco and it was fine. Still cost £120 at the time, think they're about £90 now

1988smithy said:

Fookin ell inspector closeau!

I don't see a problem with a decent siemens/vdo, as I said i fitted one to my old disco and it was fine. Still cost £120 at the time, think they're about £90 now

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Lol only because I remember sierra recommending them to me when I had problems with readings!

tom1979 said:

I’ve never had a problem with VDO, and neither have you by the looks of it

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Maybe because mine is Eu2 which has different management.... and i've learned much since that ancient post especially after a aftermarket VDO failed on me in less than 3 years then made various live comparative tests with genuine, VDO and others... here's a more recent thread https://www.landyzone.co.uk/land-rover/faulty-maf.336600/#post-4372655 ...the learning curve is ascendent