Reply With QuoteFrom memory O2s should fluctuate between 0.1 and 1.0.
Checked for vacuum leak around intake?
Does it do same with MAF disconnected?
Ignition coils?
Master
Hi all, my Discovery 2 V8 has a small stumble when the auto downshifts from third to second using about half throttle, my fuel usage is around 27-30 litres per hundred. Maf seems to be working the TPS is reading okay the 02 sensors appear to be working (unsure how to read properly they are getting voltage on the nanocom and torque app).
It has 285/75/16 4.11 diff gears and 163000 kms on it with extractors. I have had v8 discos with big tyres before so i know fuel usage is always going to be heavy but just cruising around it seems on the heavier side of normal.
I'm thinking the stumble might have something to do with it.
The head gaskets have been replaced before. the Nanocom is reading the temp okay so i presume the ecu isn't getting cold start signal all the time. It doesn't use any coolant or oil, I'm not getting any error codes showing either. Under heavy acceleration (foot to the floor from 0-110 kms/hr) the tachometer lightly fluctuates. I am out of ideas.
Cheers Nigel
Master
From memory O2s should fluctuate between 0.1 and 1.0.
Checked for vacuum leak around intake?
Does it do same with MAF disconnected?
Ignition coils?
OldBushie
SupporterI am getting about 20l per 100klm out of my V8 D2a towing a 1.5 boat that acts like a parachute when i am towing it so your fuel usage is really heavy even with the big tyres, I am running 245/70/16 Micky Thompson ATZ P3's.
Are you watching the tacho to make sure that the auto is actually locking up?
You only get one shot at life, Aim well
2004 D2 "S" V8 auto, with a few Mods gone
2007 79 Series Landcruiser V8 Ute, With a few Mods.
4.6m Quintrex boat
20' Jayco Expanda caravan gone
Master
The auto is definitely locking up in 3rd and 4th as it should. The fuel pressure regulator is ticking at idle not sure if that is normal. I haven't found a vacuum leak at this stage. I have been spraying easy start around the manifold when running with no noticeable change.
Master
When you disconnect the maf when it's running it will stall.
Master
ForumSage
SubscriberMate where are you hearing this sound. There is not pressure regulator under the bonnet in a D2 V8. Fuel pressure is dictated by the pump in the tank from memory. If you are hearing ticking it might be an exhaust manifold gasket that's blown out (easy fix) and while that will muck up what the 02 Sensors see downstream of the MAF in my experience that would not account for your horrendously high fuel consumption. Mine is half of yours with 4.6, heavy truck, lifted and 31 inch Duratracs.Originally Posted by nigelbuilding1984
Cheers
Master
The lambda A and B output at idle varies from 0.95 to 1.05 unsure of what this reading means.
ForumSage
SubscriberAt a guess the MAF is stuffed if hesitation on downshift. Is it missing? A bit hard to tell cause the V8's are so forgiving but old coil packs can cause miss under load and poor economy. You might have a couple of things needing attention.
Cheers
Master
It is on the passenger side of the engine and has a 5-6 mm vacuum hose that runs to it with a plug on it. The vacuum hose then runs out and to the rear of the manifold out of sight. It sits underneath the idle air control pipe. I'm not sure if it is the pressure regulator it just similar like one. Definitely not exhaust leak as when you crimp the vacuum hose the ticking will stop.
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