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Topic: MAF figures (Read 745 times) |
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pedropedro
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Posts: 677
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MAF figures
« on: May 19th, 2010, 6:32pm » |
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I have a gearbox flare problem 2-3 and it has been suggested that the MAF could be culprit. On another scorpio same model at 2000rpm maf reads 1.3 using obd2 sware . On mine it reads .7 at same rpm.
so i exchange the MAFs and the difference stays ..so in other words the maf from the scorp that read 1.3 now reads .7 at 2k rpm on my car...wouldnt that suggest ecu? so something in my car is causing the differential ,,its had a new wiring loom so thats not it. Maybe the difference isnt relevant i dont know enough about them but almost half the reading seems odd
why would there be that diferential? any thoughts appreciated
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Tompion
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1997 2.3 Ultima estate.
Posts: 2918
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Re: MAF figures
« Reply #1 on: May 20th, 2010, 12:04am » |
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Did you turn off the aircon whilst taking the readings?
I don’t know off hand which way a high resistance connection would affect the reading, but have you tried unplugging the big connector on the wing to reseat the pins?
Have you tried driving with the MAF disconnected to see if that affects the changes?
Dave
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ABS multiplug wheel sensor pins MK IV or MK 20
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pedropedro
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Posts: 677
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Re: MAF figures
« Reply #2 on: May 20th, 2010, 7:12am » |
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ah! maybe had air con on my one with low figures...will try with off tonight...doesnt have any codes in the system so assumed if maf was bad would show as a code
yes tried disconnecting maf and still get flare
yes had large connector off and cleaned all pins
tks for info john
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pedropedro
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Posts: 677
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Re: MAF figures
« Reply #4 on: May 20th, 2010, 10:00pm » |
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yes read that ...my concern was the reading at 2k rpm
one car read 1.4 mine reads .7
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scorpio_man
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Ford Kuga awd
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Re: MAF figures
« Reply #5 on: May 21st, 2010, 5:14am » |
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hi there
are you able to monitor the maf flow figure throughout the rev range?
is it climbing as the revs go up?
i've seen a faulty maf (flow figure was miles out (too high)), but there was no error code stored for it.
you stated that you had a new wiring loom. did that include wiring to the maf? if yes, then i'd check the output from the maf using a multimeter at the plug.
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Dave2302
Senior Member
2006 Mercedes S55 AMG, Retired Barefoot Waterskier
Posts: 1119
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Re: MAF figures
« Reply #6 on: May 21st, 2010, 8:52am » |
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AFAIK, the MAF wiring is in the car loom, not the engine loom, and can go bad like the engine looms do. Normally at or near the MAF plug they go bad.
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Dave "The 'ol Bear" ex Footer !
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pedropedro
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Posts: 677
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Re: MAF figures
« Reply #7 on: May 21st, 2010, 12:45pm » |
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yes can monitor maf ..yes climbs as revs go up
new loom DIDNT inc MAF wiring it was the engine loom that was changed
the wiring looks perfect around maf area
will have to look at volts coming out of maf tks john
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Mike H
Senior Member
Renault Clio
Posts: 2594
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Re: MAF figures
« Reply #8 on: May 21st, 2010, 1:44pm » |
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on May 21st, 2010, 5:14am, scorpio_man wrote:is it climbing as the revs go up?
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Would that be the wrong way round then?
Only cos on the maftest page he says for the screen shot example this is not at idle, and it was reading 0.2 something, which implies it goes down as air flow increases, not up (?)
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Mike H
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pedropedro
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Posts: 677
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Re: MAF figures
« Reply #9 on: May 21st, 2010, 1:49pm » |
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dont think so the maf output increases with increase of air flow
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Mike H
Senior Member
Renault Clio
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Re: MAF figures
« Reply #10 on: May 21st, 2010, 2:05pm » |
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Well that would allow for a bigger range! 
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Mike H
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Tompion
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1997 2.3 Ultima estate.
Posts: 2918
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Re: MAF figures
« Reply #11 on: May 23rd, 2010, 12:11am » |
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As promised in the other thread here are the readings I got from my 2.3. I found the values for the MAF fluctuated a little & quite tricky to keep the revs steady.
MAF (pounds/min)
Tickover (884rpm)
0.3 (0.46 with aircon on)
2000rpm
0.9 (1.2 with aircon on)
With an air leak (the air hose to the fuel pressure regulator disconnected):
Tickover (890rpm)
0.161 (0.287 with aircon on)
2000rpm
0.64 (0.95 with aircon on)
I took some other sensor readings:
Ambient temperature 21.5C
ECT 194 – 208F
IAT 127F
Barometric pressure 30.3
Transmission fluid 173 – 191F
TPS 16.9%
Don’t forget the TPS can affect the changes, check it with ignition on engine off the readings should increase smoothly as you press the throttle. If the reading at rest isn’t around 16% disconnect the battery for a while to let it reset.
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pedropedro
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Posts: 677
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Re: MAF figures
« Reply #12 on: May 23rd, 2010, 10:36am » |
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tks for that info...ive just run engine on ve sware and figures are same as yours..the tp is 16% at idle ..maf at idle a bit higher
with a/c on at idle .6 @ 2k rpm 1.2
I think a number of folk suggested maf could be main cause of flare 2-3, that's i was focused on that perhaps too much....it's had a replacement gearbox & flares etc ....perfect in winter mode, better with a/c on
changed ecu ......has to be the valve assy/chest in gearbox.
i had another box with same problem no one could fix..I am assuming the valves are difficult to test..will insist the gearbox people send it away for professional testing and sort this...tks for interest john
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Dave2302
Senior Member
2006 Mercedes S55 AMG, Retired Barefoot Waterskier
Posts: 1119
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Re: MAF figures
« Reply #13 on: May 23rd, 2010, 11:37am » |
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I have a known good valve chest here if it's any use to you,
Regards Dave
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Dave "The 'ol Bear" ex Footer !
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pedropedro
Full Member
Posts: 677
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Re: MAF figures
« Reply #14 on: May 23rd, 2010, 12:00pm » |
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Dave
that would be really useful ...appreciate your help
yes if I can take you up on that please...how much carriage etc?
pm me ? rgds John
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