Reply With QuoteThat could be a good suggestion.Originally Posted by sierrafery
YarnMaster
Can't you borrow a MAF from somebody who doesnt have problems though? the fact that it's made by VDO but not labelled as Genuine is not a 100% guarantee that it's perfect, the genuine parts are made by the manufacturer(in this case VDO) to meet very strict requirements and high standards imposed by the customer(in this case L.R.) which have to pass restrictive bench tests(these are the most expensives), those parts which failed the high standard tests but still within generaly accepted limitst or the same parts made by the same manufaturer but without taking so much care for the details or without using high spec materials are named OEM(as they are made by the original equipment's manufacturer), so a kinda aftermarket parts made by a reliable manufacturer(cheaper),... then there are "OEM quality" aftermarkets made by manufacturers with good reputation and known brand approx at the same price as OEMs ,,, and the last option are aftermarkets made by chinese or no-name builders which are the cheapest and a lottery, my father used to work for Lucas Automotive before he retired many years ago and that's how i know.... sellers are often naming "genuine" some OEM parts especially on ebay but that's not always true. The best example which is visible with naked eye is to buy a Genuine L.R. labelled drive belt and a OEM one and compare
anyway, IMO there's no reason for a well working MAF to exceed the max admitted reading unless the real air flow is so high which should bring same high boost with it too, better than clamp the output you should try to put a voltage stabiliser on the supply to keep it 12V steady cos it's possible that the alternator output to be higher at those high revs and maybe that would make it overread... the nanocom voltage reading is extracted from other source than the MAF supply which is from the engine bay fusebox almost directly from alternator and can be higher then the output is higher too, or bring a wire into the cabin from fuse F2 and let a voltmeter connected to it to see the MAF supply when it cuts out
Discovery Td5 (2000), manual, tuned
Wizard
That could be a good suggestion.
Master
In my case its not a faulty MAF.. I have a biggish turbo and its sucking a whole lot of air. I am going to try and voltage clamp it again and see how that turns out.
Wizard
My problem is similar to yours. My MAF is not faulty, that is why i was going to clamp the voltage as well.
Do you think it will make much difference to the fuel mixture? Or is that more based on boost pressure from the MAP sensor? The MAF obviously makes a difference to the way the car runs at part throttle, not sure how much difference it will make at full throttle with max air flow?
For example if we clamp the voltage at 5V and effectively the flow of air could equal 7V (for argument sake) what effect would that have on engine performance and calculations?
If it was naturally aspirated i'd guess it would mean the fuel ratio might be incorrect and the engine would run lean. (More air per fuel) But for a turbo engine i'm guessing the volume of air being sucked into the engine is more determined by the boost pressure and air temp. (Both measured by the MAP sensor as far as i'm aware)
So while i believe the MAF is important, what effect would it make at full throttle and full boost if the voltage was clamped? As this is where i have the issue.
If the MAF was maxing out at half throttle and half boost i can imagine the solution would have to be different.
Master
I haven't noticed much difference in fuel usage yet.. With the MAF connected and the new tune apart from the air cutting I get a nasty 1st to 2nd gear change, I think its the MAF confusing the auto. Disconnected it's all good apart from the 30sec delay on start up. I don't think the MAF on the td5 has anything to do with fuel ratio but i do remember reading it can effect the shift patterns and fuel consumption at altitude but I am probably wrong.
I have order a few 4.7V diodes to try so i'll report back over the break.
YarnMaster
1. Ther MAF's own electronic is limiting the output to 5V but above 4.8V it exceeds the 680 reading for the ECU and it cuts out, i'm still not convinced that your MAF is good untill you dont try with a new genuine one or borrow one from a non-problematic car, IMO excessive reading of a 100% good MAF can be caused only by too high feed or too high air flow/sucction which we spoke why can happen
2. IMO with clamped MAF there will be no controll of excessive air flow so no certainity that the turbo is not overspeeding
Discovery Td5 (2000), manual, tuned
Master
My friends at Ritter let me try 2 or 3 new ones before i gave in... its not my MAF.
Td5 was designed with a 2052 turbo... i am running a 2260 turbo.. = lots of air.
YarnMaster
So what i said is valid in your case = excessive suction, all my statements are for normal turbo setup not such ''agressive'' tuning, even a boost box can make the MAF exceed it's readings cos all the system/management was calibrated for factory setup
Discovery Td5 (2000), manual, tuned
Wizard
If it was self limited to 5VDDC what would you expect Nanocom to read above 680? My Nanocom reads up to approx 650-670 (There is a delay in the reading display), then surges, then Nanocom reads 0 and the car takes off as if it had no problem.
I understand your point but I do not feel my MAF is 'faulty' perhaps it is 'not to factory specification'
If I had another to test with I would, it is a fair bit of money to spend just to prove the failure. Especially considering my MAF is not even 6 months old.
Master
Jazzman.. I am in Burwood, Vic.. come past one night I have a few MAFs we could test.
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