Overboost but not overboost

tom1979 · Jun 18, 2022

Evening! Strange one, every now and then I get what seems to be a fuel cut but no fault codes logged and happens to quick to identify anything in live data. If the problem gets worse I'll suspect injector seals (changed around 2 years ago with genuine), but currently only does it when accelerating when in 4th gear around 30-40mph. Seems to "build up" then just cut momentarily.

I've smoke tested the intake system & exhaust system, fuel pressure test, removed air filter, changed intercooler hoses for Samco hoses, brand new Pierburg WGM. I haven't tried unplugging the MAF yet, although that is only a year old and a VDO one.

Anyone had this before?

2003 D2 Manual 125k miles.

sierrafery · Jun 19, 2022

tom1979 said:
I haven't tried unplugging the MAF yet, although that is only a year old and a VDO one.

Hi, just unplug it and see what happens cos it's quite common for Eu3s to have that "MAF cut-out" syndrome and without the sensor to be bad, it can be just a slight boost leak at the wastegate which will not be visible so if the symptom goes away with MAF unplugged that's it even though VDO MAF is not like genuine

tom1979 · Jun 20, 2022

So I drove down to the Malvern show yesterday, 115 miles each way. Driving down it hesitated about a dozen times and even driving steadily I felt it pull back a bit once. So before we left I unplugged the MAF - nothing since. Put another new VDO on this morning and still not doing it. Hopefully the MAF was at fault!

Discodevon · Jun 21, 2022

tom1979 said:
So I drove down to the Malvern show yesterday, 115 miles each way. Driving down it hesitated about a dozen times and even driving steadily I felt it pull back a bit once. So before we left I unplugged the MAF - nothing since. Put another new VDO on this morning and still not doing it. Hopefully the MAF was at fault!

Good to hear mate, I never had much luck with vdo maf sensors, seem to have went through them once a year, the genuine ones seemed to last better

tom1979 · Jun 21, 2022

Discodevon said:
Good to hear mate, I never had much luck with vdo maf sensors, seem to have went through them once a year, the genuine ones seemed to last better

How much were you paying for a genuine one?

Discodevon · Jun 21, 2022

tom1979 said:
How much were you paying for a genuine one?

The first one in 2016 was about 125 quid I think, then the second 2 years ago I somehow won on eBay for 55 quid

tom1979 · Jun 21, 2022

That's pretty good, they are more than that now!

Discodevon · Jun 21, 2022

tom1979 said:
That's pretty good, they are more than that now!

You will get a better price than I would from Land Rover though, they see my coming from a mile off lol

sierrafery · Jun 21, 2022

On Eu3 engine it's better to drive it with MAF unplugged if you dont have a genuine LR, any other MAF no matter who made it is wasted money

tom1979 · Jun 21, 2022

Discodevon said:
You will get a better price than I would from Land Rover though, they see my coming from a mile off lol

Don't believe it!!

sierrafery said:
On Eu3 engine it's better to drive it with MAF unplugged if you dont have a genuine LR, any other MAF no matter who made it is wasted money

What is the issue with Siemens VDO/Continental air flow sensors?

sierrafery · Jun 22, 2022

tom1979 said:
What is the issue with Siemens VDO/Continental air flow sensors?

The issue is that they are not good enough to become genuine LR so as good as any other aftermarket, i'll not go into that debate again https://www.landyzone.co.uk/land-rover/d2-td5-cutting-out-when-warm.326582/#post-4193511 eventually read the whole thread cos it's revelatory

tom1979 · Jun 22, 2022

sierrafery said:
The issue is that they are not good enough to become genuine LR so as good as any other aftermarket, i'll not go into that debate again https://www.landyzone.co.uk/land-rover/d2-td5-cutting-out-when-warm.326582/#post-4193511 eventually read the whole thread cos it's revelatory

I wasn't questioning the overall statement as I remember reading it at the time, I was just asking if you knew what was physically different - whether the casing is different altering the flow or if they use a different heater element etc.

tom1979 · Jun 22, 2022

Update, MAF didn’t solve the problem as it cut out again on the way home from work! This time it cut out completely, and the EML came on.
Haven’t got a Nanocom here to see if there’s codes but now suspecting either injector seals or possibly crank sensor.
5th gear, 30mph and foot flat down it seems to reliably cut out

sierrafery · Jun 22, 2022

The injector seals would not trigger the EML whatsoever, crank sensor or low fuel pressure which used to cause a false driver demand fault code which being related to the TPS can also bring on the EML

tom1979 · Jun 22, 2022

It started again straightaway with no priming required so seals are unlikely, I'll see what codes are stored if any and go from there.

Discodevon · Jun 22, 2022

tom1979 said:
It started again straightaway with no priming required so seals are unlikely, I'll see what codes are stored if any and go from there.

Sounds like your pump is on the way out, have you ever changed it since in your ownership? If it’s on your disco it’s quite easy to change, even I did it on my old discovery lol

tom1979 · Jun 22, 2022

Discodevon said:
Sounds like your pump is on the way out, have you ever changed it since in your ownership? If it’s on your disco it’s quite easy to change, even I did it on my old discovery lol

Yes it had a VDO one about 18 months/1500 miles ago. Yes they are a lot easier to change in the D2's, although I made an access hatch in my Defender!

The only main components I haven't changed are the fuel filter housing and the radiator.

Discodevon · Jun 22, 2022

sierrafery said:
The injector seals would not trigger the EML whatsoever, crank sensor or low fuel pressure which used to cause a false driver demand fault code which being related to the TPS can also bring on the EML

I know you are pretty keen on using genuine parts ( I am too ) but what about the fuel pump?

Discodevon · Jun 22, 2022

tom1979 said:
Yes it had a VDO one about 18 months/1500 miles ago. Yes they are a lot easier to change in the D2's, although I made an access hatch in my Defender!

The only main components I haven't changed are the fuel filter housing and the radiator.

Can’t see why the pump would be faulty after a year, but I guess these things do happen

tom1979 · Jun 22, 2022

Discodevon said:
Can’t see why the pump would be faulty after a year, but I guess these things do happen

It's not impossible but fuel issues won't put the EML on, my money is on the crank sensor but I won't know until tomorrow. A genuine LR fuel pump is going to be around £375+VAT, I have no idea if they are worth it. We have had very good results with Intermotor fuel pumps which are around £75+VAT. I would still always recommend at least a VDO but the Intermotor ones aren't noisy like the cheap ones and so far not had any returns. Most fuel pump failures are caused by people running out of fuel or injector seal failure. I've had a VDO one on my Defender for around 6 years with no issues.

Overboost but not overboost

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