ES4 said:

I was also thinking cat blockage at the higher revs, would that explain the low MAF readings,

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The MAF readings are dependant on sucction of air which passes throug the turbo into the inlet and then to exhaust, if the exhaust is blocked there will be no sucction as well... it's a kind of an "air loop" which needs to be free all the way if you see what i mean, that's why on performance tunings they fit straight through exhaust... on Eu3 engines the MAF reading is very important... a well running Eu3 engine goes up to arund 600 Kg/hr under load

hi, dc volts is 14v + when alternator running, but the air filter is due to be changed which Ill do shortly = fuel.

The charging is no factor now IMO. Unplug the MAF and test it so... if it's not genuine LR or old it can mix up things so if it runs better with it unplugged you need a new frigging expensive GENUINE one

Hi, I'll do that on the next run, I forgot about that, I get then filters done as well and let you know, Thanks

Hi, apart from changing the filters, I agree that what you suggest about Air flow could be the problem, at the higher revs were not getting the throughput. (low MAF) so I'll work on this first and let you know the outcome. Its one of those problems that don't show up on a normal run so we have to hitch the trailer up find a hill avoid traffic etc and re-test

Hello Again, for those of you that have been following this thread, this is what we have done using the advice given.

Clean Oil from ECU Plugs

Remove turbo/intercooler pipes and check for de-lamination

Renew wastegate Modulator valve and vacuum pipes

Clean MAP, MAF

Replace Air, Fuel, Oil Filters + oil

Replace Injector Harness

Check NO Black smoke on acceleration

We have cured the Surging Problem when towing uphill with trailer (original Fault)

And it pulls better than before.

I have attached screen shop showing new and old data, ( couldn't attach full spread sheet ?)

I don’t think the numbers are much better than before the fault
These are the Maximums when towing uphill ( about 2.5 ton)



Apologies to Sierrafery as he did ask if the ECU was re-mapped it wasn’t but when we changed the injector harness, we found a Chip Express Box wired into the harness. We disconnected it and the Discovery was quite slow on acceleration. Reconnected the box which was on its middle setting and the increase in acceleration was quite substantial. So the chip Express makes a huge difference when connected. The spread sheet attached is with the box attached and working.

Thanks.

Hi, tighten the wastegate rod to 11 threads left from the locknut cos the boost is still low while the sucction at 573 is close to normal ...if it goes to overboost go back one thread but if it doesnt go to at least 230 MAP it's possible that the turbo cartridge is worn or something...read again post 20