lamda voltages WOT
19 October 2003, 12:58 AM
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what sort of voltage would u class as to low
as to say that the engine is running to lean?
i noticed tonite that mine was about 796mv while on WOT in 5th gear, i backed of as this is the lowest i have ever seen, my boost preasure had increased to 1.3 bar :s
dawse re-adjusted to about 1.2 bar and the voltage went to about 855mv
what is classed as to much?
i rember andrew c telling me in a email after i installed the scoobymonitor that it should be about 850mv, but how far acn u push it?
as to say that the engine is running to lean?
i noticed tonite that mine was about 796mv while on WOT in 5th gear, i backed of as this is the lowest i have ever seen, my boost preasure had increased to 1.3 bar :s
dawse re-adjusted to about 1.2 bar and the voltage went to about 855mv
what is classed as to much?
i rember andrew c telling me in a email after i installed the scoobymonitor that it should be about 850mv, but how far acn u push it?
19 October 2003, 03:05 PM
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Stockers are above 0.90 volts. As John said, MAF or lamda, maybe fauly injector(s) or a faulty fuel pump.
Cars that are mapped, get readings of around 0.88/0.89volts. Mappers lean out the mix a little for better performance. Your readings are way too low. Get it checked ASAP and do not give the car any stick whatsoever.
Cheers,
George.
[Edited by WREXY - 10/19/2003 3:07:50 PM]
Cars that are mapped, get readings of around 0.88/0.89volts. Mappers lean out the mix a little for better performance. Your readings are way too low. Get it checked ASAP and do not give the car any stick whatsoever.
Cheers,
George.
[Edited by WREXY - 10/19/2003 3:07:50 PM]
19 October 2003, 04:51 PM
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actualy, just wondering, if the mixture is to lean shouldnt there be sum king od A/F correction going on?
ive never ever seen the a/f correction move, or is this for sumthing else?
ive never ever seen the a/f correction move, or is this for sumthing else?
19 October 2003, 04:56 PM
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Comments on Air Fuel Correction
When the fuelling is under closed loop control by the lambda sensor(s), this refers to the amount of fuel added or subtracted from the value retrieved from the fuel map. -5% would mean that the ecu is fuelling 5% less than the map says in order to achieve the ideal air/fuel ratio. Under high loads, the ECU switches off closed loop control, and uses values from the map. At this point, you will see AFC drop to 0%. This is why it is important that fuelling mapping is accurate (or at least rich) at high loads - the ECU does not compensate for errors here.
When the fuelling is under closed loop control by the lambda sensor(s), this refers to the amount of fuel added or subtracted from the value retrieved from the fuel map. -5% would mean that the ecu is fuelling 5% less than the map says in order to achieve the ideal air/fuel ratio. Under high loads, the ECU switches off closed loop control, and uses values from the map. At this point, you will see AFC drop to 0%. This is why it is important that fuelling mapping is accurate (or at least rich) at high loads - the ECU does not compensate for errors here.
it does move about on closed loop running
my injector duty cycles are at 90% would a uprated fuel pump be of any benifit?
1st things 1st tho, i will give a spare maf a try and see if theres any diffrence
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19 October 2003, 05:25 PM
#8
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I constantly see 0.940-0.980 on my afr all confirmed by Delta Dash too
Previously I was seeing very low readings (long thread on here about it) turned out it was a lambda on its way out, so I bought a cheapie from halfords for 25 quid, been working great ever since
But now my MAF has started showing slightly lower than normal voltages on Delta Dash, so a new MAF sensor is on order too
Previously I was seeing very low readings (long thread on here about it) turned out it was a lambda on its way out, so I bought a cheapie from halfords for 25 quid, been working great ever since
But now my MAF has started showing slightly lower than normal voltages on Delta Dash, so a new MAF sensor is on order too
19 October 2003, 07:12 PM
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i have just picked up a spare MAF from a mate, ill try it tomorow to see if theres any diffrence
heres hopeing its just the lambda
i belive the 97/98 maf is the full blown "£300 nicker to fix" version?
heres hopeing its just the lambda
i belive the 97/98 maf is the full blown "£300 nicker to fix" version?
19 October 2003, 07:36 PM
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found this on the ecutek site
there saying that values over 700 are ok?
anybody got any other views?
Front & Rear O2 Sensors
These parameters report the output voltage of the O2 sensors. Early vehicles tend to have a single 'Front O2 Sensor', whereas newer vehicles have both a 'Front A/F Sensor' and a 'Rear O2 Sensor'. These sensors do not report an accurate air/fuel ratio, but instead provide a rich/lean signal to the ECU. Their output voltages switches sharply as the AFR crosses the stoichiometric ratio. Values of approx 0 to 0.9 Volts are normal. 0 being lean, 0.9 being very rich. The sensor voltage will oscillate between these extremes when under closed loop control. Under high loads, the voltage should never drop below 0.7 Volts. If it does, this means that the fuel mixture is too lean when on boost. Quite possibly there is a fault with the air flow sensor.
These parameters report the output voltage of the O2 sensors. Early vehicles tend to have a single 'Front O2 Sensor', whereas newer vehicles have both a 'Front A/F Sensor' and a 'Rear O2 Sensor'. These sensors do not report an accurate air/fuel ratio, but instead provide a rich/lean signal to the ECU. Their output voltages switches sharply as the AFR crosses the stoichiometric ratio. Values of approx 0 to 0.9 Volts are normal. 0 being lean, 0.9 being very rich. The sensor voltage will oscillate between these extremes when under closed loop control. Under high loads, the voltage should never drop below 0.7 Volts. If it does, this means that the fuel mixture is too lean when on boost. Quite possibly there is a fault with the air flow sensor.
anybody got any other views?
19 October 2003, 09:09 PM
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As WREXY said. 700mV will blow up your engine if that is a reading from a healthy lambda sensor on full boost (on part throttle part boost maybe). For a normally aspirated car it might be OK, but probably still a bit lean, depending on placement of the sensor. On a Scooby 700 is dangerous or a faulty lambda.
[Edited by john banks - 10/19/2003 9:10:08 PM]
[Edited by john banks - 10/19/2003 9:10:08 PM]
19 October 2003, 11:23 PM
#12
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The cheap Halfords sensor reads differently to the oem one so your 0.98 volts may well be indicating something different in afr terms, on wot, the lambda sensor output should exceed 0.9 volts for safe fueling, its difficult to tell what is ok or not ok as these sensors become tired and their output drops with age. get it checked by someone with a good wideband setup if you are not sure.
cheers
bob
cheers
bob
20 October 2003, 08:09 AM
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Micky,
Have you got an induction kit? This can make the MAF read slightly lean.
I think I actually said:
.
Weren't your injectors over 90% at 1.2bar?
Andrew...
Have you got an induction kit? This can make the MAF read slightly lean.
I think I actually said:
AFR will up and down whilst the ECU is closed loop, under full throttle should be 860->900mV
Weren't your injectors over 90% at 1.2bar?
Andrew...
20 October 2003, 06:20 PM
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they were 90% when i first fitted the monitor and have never changed
never saw anything more then 90%
i tried to fit this spare MAF from a mate jst b4 and it doesnt fit
, aperently its from a 97uk model
its 2 small
the sticker on it is the purple one, the one i have on the car had a orange serial sticker and is physicaly bigger in size
i removed and and looked inside and the arangement of the wires and such is also diffrent, same basic design but layed out ina diffrent manner
MAF was clean inside but the "plate" type thing at the back after the "bulb filiment" type thing was very very dirty
i dippeda cotten bud in tar and glue remover and cleaned the plate thing, i got a lot of sirt off, i had a quick wipe of the bulb filement thing but had to hurry up as it was getting dark and i need the car for niteshift tonite
refitted it and started the car
the idle is a lot more smooth, the AFC is a lot more stable @ idle
wheres b4 it just seamed to be jumping about random style now it actualy goes up and down in increments, like +1 +2 +3 +3 +2 +1, which i asume is correct
i didt want to test the car in full wot @ high revs cos its raining and the rpads were busy, i will try on my way to work tonite when its deserted
i plan to remove the MAF again on saturday or simmiler (when i have plenty of light) and clean it up properly
anybody know if the P1 MAF is the bigger (orange) size?, i asume its the same as a STI?
never saw anything more then 90%
i tried to fit this spare MAF from a mate jst b4 and it doesnt fit
, aperently its from a 97uk model
its 2 small
the sticker on it is the purple one, the one i have on the car had a orange serial sticker and is physicaly bigger in size
i removed and and looked inside and the arangement of the wires and such is also diffrent, same basic design but layed out ina diffrent manner
MAF was clean inside but the "plate" type thing at the back after the "bulb filiment" type thing was very very dirty
i dippeda cotten bud in tar and glue remover and cleaned the plate thing, i got a lot of sirt off, i had a quick wipe of the bulb filement thing but had to hurry up as it was getting dark and i need the car for niteshift tonite
refitted it and started the car
the idle is a lot more smooth, the AFC is a lot more stable @ idle
wheres b4 it just seamed to be jumping about random style now it actualy goes up and down in increments, like +1 +2 +3 +3 +2 +1, which i asume is correct
i didt want to test the car in full wot @ high revs cos its raining and the rpads were busy, i will try on my way to work tonite when its deserted
i plan to remove the MAF again on saturday or simmiler (when i have plenty of light) and clean it up properly
anybody know if the P1 MAF is the bigger (orange) size?, i asume its the same as a STI?
20 October 2003, 10:21 PM
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The P1, STI and UK MAFs are all identical. Part number is 22794AA010 METER CP-AIR FLOW. The MAF must come from either a MY99 or MY00. The other model's MAF sensors are different.
Cheers,
George.
Cheers,
George.
21 October 2003, 07:43 AM
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i have a MY 97 WRX and my maf is not the same as my mates uk car, he bought a spare as he had problems, his uk car was a simmiler year, hence why i have one available to play with, i am aware that the early cars are diffrent,
the maf on my car is the same design, just bigger in circumfrance, and has a orange serial sticker instead of purple, alsi the layout of the internals is diffrent and mine is collour orange inside, his is all black
the smaller unit will not fit my airbox, and i suspect my inlet pipe (never tried the pipe) i am asuming that the higher powerd models got a larger intake (seams plauseble)
another question, lambda voltages, do they increase smoothly or jump?
i always see the same values eg jumping from say 796 to 815 to 836 to 855, it never increases smoothly, should it?
i will try and get sum pics of the 2 Mafs when i wake up (i have just finnished niteshift and im fux0red)
the maf on my car is the same design, just bigger in circumfrance, and has a orange serial sticker instead of purple, alsi the layout of the internals is diffrent and mine is collour orange inside, his is all black
the smaller unit will not fit my airbox, and i suspect my inlet pipe (never tried the pipe) i am asuming that the higher powerd models got a larger intake (seams plauseble)
another question, lambda voltages, do they increase smoothly or jump?
i always see the same values eg jumping from say 796 to 815 to 836 to 855, it never increases smoothly, should it?
i will try and get sum pics of the 2 Mafs when i wake up (i have just finnished niteshift and im fux0red)
22 October 2003, 08:02 AM
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do u know much about the readings from the lambda sensor with regards to the select monitor port?
my readings dont increase or for the matter, decrease smoothly, they jump in steps, the steps are conistent in that i see the same figures every single time as it increases
should it register like this or should it increase progressivly
ie 612 613 614
my readings dont increase or for the matter, decrease smoothly, they jump in steps, the steps are conistent in that i see the same figures every single time as it increases
should it register like this or should it increase progressivly
ie 612 613 614
22 October 2003, 10:36 AM
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Micky,
The lambda figures from the Select port from an ADC (within the ECU) of the actual voltage so it will be stepped and the steps will be of nearly equal size.
The value from the ECU is in the range 0-255 representing 0-5.05volts (on the cars I have measured with a DVM anyway), when the monitor converts this back to a voltage it gives steps of 19-20mV.
You can see by this that the monitor will always read a little low as the ECUs representation of the actual voltage is rounded down, eg display 855mV may be as much as 874mV on a DVM.
Andrew...
The lambda figures from the Select port from an ADC (within the ECU) of the actual voltage so it will be stepped and the steps will be of nearly equal size.
The value from the ECU is in the range 0-255 representing 0-5.05volts (on the cars I have measured with a DVM anyway), when the monitor converts this back to a voltage it gives steps of 19-20mV.
You can see by this that the monitor will always read a little low as the ECUs representation of the actual voltage is rounded down, eg display 855mV may be as much as 874mV on a DVM.
Andrew...
22 October 2003, 02:58 PM
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This is how mine read with Delta Dash. This is with a JB Tek 3.
Revs O2 readings
4171 0.855
4335 0.865
4486 0.875
4653 0.875
4808 0.875
4928 0.885
5109 0.875
5226 0.875
5400 0.88
5527 0.885
5682 0.885
5778 0.89
5919 0.885
6053 0.885
6173 0.885
6281 0.88
6410 0.885
6510 0.88
6631 0.88
6751 0.875
6862 0.875
6399 0.795
Cheers,
George.
[Edited by WREXY - 10/22/2003 3:01:38 PM]
Revs O2 readings
4171 0.855
4335 0.865
4486 0.875
4653 0.875
4808 0.875
4928 0.885
5109 0.875
5226 0.875
5400 0.88
5527 0.885
5682 0.885
5778 0.89
5919 0.885
6053 0.885
6173 0.885
6281 0.88
6410 0.885
6510 0.88
6631 0.88
6751 0.875
6862 0.875
6399 0.795
Cheers,
George.
[Edited by WREXY - 10/22/2003 3:01:38 PM]
22 October 2003, 05:12 PM
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when i fitted the scooby monitor the car was hitting 1.35 bar boost as a spike, and then holding 1.1 bar
i fitted a dawse device and set the boost @ 1.2
so technicaly i am running a touch less boost then before, although its actualy holding a touch more, if u know what i mean, i will try a lambda sensor before i splash out on a MAF as it should be a touch cheaper on the wallet.
i fitted a dawse device and set the boost @ 1.2
so technicaly i am running a touch less boost then before, although its actualy holding a touch more, if u know what i mean, i will try a lambda sensor before i splash out on a MAF as it should be a touch cheaper on the wallet.
22 October 2003, 09:48 PM
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AndrewC
cheers thats what i was thinking, as im pretty sure it may actualy go above 855, i just thought the stepping might indicate a problem with the lambda sensor, if its supposed to do that then thats one less idea to bounce around my head, i have another idea for a test
to turn the boost right down and see what the display reads while under boosted
cheers thats what i was thinking, as im pretty sure it may actualy go above 855, i just thought the stepping might indicate a problem with the lambda sensor, if its supposed to do that then thats one less idea to bounce around my head, i have another idea for a test
to turn the boost right down and see what the display reads while under boosted
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