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MY V8 RUNNING RUFF plus a wierd air flow problem???

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Ja1983:
replace with some nice big SU`s.... whoe need sfuel economy?! :lol:

with the compression been a little skewe wiff (10.3 > 11 BAR) does the missing correspond with the hi/lo cylinder...  ie, could there be a slack valve seal or maybe something which could be throwing the lambda off?

..i know very little about V8`s and ecu`s seem to be very troublesome, hence the opening line, maybe a bit of a bad connection on the Air flow meter, that is disturbed when you opened the airbox?

hope you solve it soon! :D

Range Rover Blues:
It was the earlier flapper type EFi that gained a bad reputation, the hot wire is a far more robust system with some degree of sensor redundancy, plus simple plug in diganostic, not that it always tells you what's going on.

Rossko:

--- Quote from: "Range Rover Blues" ---Anyway, I thought the MAF sensor looked odd, till you pointed out it's from a GEMS stystem.  Have you tried putting the correct one back in?
--- End quote ---


There's a big hint for you there.  If this engine is running a 14CUX ECU, as a 3.9 should, you should have either a 3AM or 5AM boxy looking airflow meter.  That is the same as a 4.2 - but quite different to a 4.6 one, which is what you appear to have fitted in the video!

I don't think you can directly swap 3AM and 5AM units, although they both look alike and both work with a 14CUX - the 14CUX comes in different versions to suit.

disco-v8:

--- Quote from: "Rossko" ---
--- Quote from: "Range Rover Blues" ---Anyway, I thought the MAF sensor looked odd, till you pointed out it's from a GEMS stystem.  Have you tried putting the correct one back in?
--- End quote ---


There's a big hint for you there.  If this engine is running a 14CUX ECU, as a 3.9 should, you should have either a 3AM or 5AM boxy looking airflow meter.  That is the same as a 4.2 - but quite different to a 4.6 one, which is what you appear to have fitted in the video!

I don't think you can directly swap 3AM and 5AM units, although they both look alike and both work with a 14CUX - the 14CUX comes in different versions to suit.
--- End quote ---



sorry will have to totaly disagree with you on that one, the gems 20AM AFM is a comon swop for big V8's as the air flow is ment to be something like 20% better as it has a larger through, the air flow meter sorts all the tricky stuff out and send the same sort of reading back to the ECU, then the ECU decieds what to do.......
the only difference is that the 3/5AM AFM have 4 wires and the 20AM has only 3..... but the extra wire is for a built in adjuster pot to calibrate the CO at idle on the 3/5AM which is built into the AFM , but the 20AM doesnt have this so you have to wire it up your self and calibrate it to 1.8V for a CAT and 1.5V for none CAT...... i used the old pot out of my old AFM and wired it up that way....

jaysastud:
not sure if it helps,everyone is looking at the technical stuff!but i hve had probs a litle like this before on sports cars,the prob was the air flow goes up and so should the fuel,but ive had the problemht the fuel pump isnt good enough to cope,all goes odd,ecu cant cope and it all just goes belly up!basically too much air and not enough fuel.not sure if that helps as havent checked the vidsas pc gone all odd,but it may be about the same problem?if not no idea sorry!

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