A little MAF question
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Thread: A little MAF question

  1. #1
    Tadpole
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    Default A little MAF question

    Oscar is a 2006 Pug 307 with the RHR engine, my question for whatever reason, lets say I want to fit a gauge, is on the plug to the MAF unit which wire signals the mass air flow. My little mind has itself thinking one wire say 3 is for the intake air temperature and I think 4 is for the flow. 1 seems to be the power which must be internally reduced to the universal 5 Volt that chips require, and I think 2 would be the ground but I'm sure open to suggestions as by myself it's not easy to play with the throttle and check voltages.

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  2. #2
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    Hi jimby
    Just a generic answer as I do not know about your specific unit. The signal coming out of a MAF sensor probably needs to be 'processed' by the ECU to be useful. For instance the temperature is probably read by a NTR which has to have a voltage put across it and the current read which is then compared to a look-up table by the ECU to get a temperature 'unit' which it uses. I am not sure how that could be interperted by an external meter.
    Any readings would have to be by a high impedance meter circuit so the signal is not degraded. OR you can use a unit which plugs into the OBD port to get real time sensor information from the ECU via the 'bus'. Look on Ebay for ideas. I am not sure if your model allows this, but if it does you can see a lot of information that is being used all the time. Just the same as new cars will tell you the air temperature.
    Jaahn

  3. #3
    Fellow Frogger!
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    Quote Originally Posted by jimby View Post
    by myself it's not easy to play with the throttle and check voltages.
    Also just a general suggestion... you can buy things on ebay for back probing wiring connectors. They have a very thing probe of stiff metal, and allow DMM cables to be connected at the other end. Combine that with some long DMM leads and you can read the voltages from anywhere eg while sitting in the drivers seat.

    eg
    https://www.ebay.com.au/itm/Flexible...frcectupt=true

    You can also buy OEM workshop manuals on ebay either on DVD or for digital download. The wiring diagrams take a bit of head realignment to understand and use effectively, but every detail is there, including all the connectors, sensors, hardware, wire colors etc. They cost ~$10. I recommend buying one for every car you own.

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    Quote Originally Posted by 1972Ren View Post
    Also just a general suggestion... you can buy things on ebay for back probing wiring connectors. They have a very thing probe of stiff metal, and allow DMM cables to be connected at the other end. Combine that with some long DMM leads and you can read the voltages from anywhere eg while sitting in the drivers seat.
    https://www.ebay.com.au/itm/Flexible...frcectupt=true
    You can also buy OEM workshop manuals on ebay either on DVD or for digital download. The wiring diagrams take a bit of head realignment to understand and use effectively, but every detail is there, including all the connectors, sensors, hardware, wire colors etc. They cost ~$10. I recommend buying one for every car you own.
    Hi jimby
    Good suggestions by 172ren. If you want to read voltage then you can use long leads from the item to the other end of the car if you want. Buy them or make some. But you must use a digital multimeter (or similar) as they have a high impedance input that draws tiny current and does not upset the source voltage. You cannot use a simple analogue meter (or test lamp) for that.

    But if you do not have a digital meter then get one now as they are necessary and indispensable for trouble shooting modern cars. I always suggest a auto ranging meter of slightly more cost than the real cheapies. They are self protected against a lot of abuse and will last for a long time. Also an automotive use type meter may have a couple of useful functions rather than one mostly for electronic tinkering.
    Jaahn
    Last edited by jaahn; 20th January 2020 at 06:09 PM.

  5. #5
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    Thanks for the replies friends but I think we're all overthinking things. Anyway I've tinkered with the number 4 and it seems that it is indeed the MAF output. Really I'm wishing to adjust the output down a bit so Oscar thinks he's at a bit more altitude, you can likely figure out why but I'm reluctant to mention it, I'm new to the group and to Peugeot and I don't want to rock the boat. I'm not looking for any extra power, Oscar has ample.

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    Overcome your reluctance, jimby . If it's not for more power then it's got to be fuel economy? If so, good luck to do better than the factory.
    "The enemy of knowledge is not ignorance, it's the illusion of knowledge"
    Stephen Hawking

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    Hi jimby
    We do not care what you are doing, but are always interested in tinkering. Possibly giving answers to questions that you never asked even !

    If you fool the ECU into thinking that there is less air so it will give less fuel then because it monitors the exhaust O2, for most normal running, it will adjust the mixture to change it 'correct' again.

    Ask any questions we do like a bit of two way discussion also
    Jaahn

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    I'm aiming to have the ECU believe that the mixture of fresh clean air and poopy EGR air are proper enough not to trigger alarm bells. It's still a work in progress but at this stage I'm using a voltage divider consisting of a 10k resistor and a trimpot that I've wound 196 Ohms into, a mere 2% reduction but so far so good. This is tinkering work from blanking the EGR. I had already placed a 50% voltage divider in parallel across the EGR plug but still had the CEL pop up from time to time. Trying to adjust the MAF by more than that 2% brought up a CEL in very short time.
    Whatever I have done has improved the economy but the EGR is such a minor thing it's really only to keep things a bit cleaner internally and I can see that Oscar's oil thinks very positively about it.

  9. #9
    1000+ Posts dmccurtayne's Avatar
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    So how are you getting the egr position back to the ecu ?


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    Quote Originally Posted by dmccurtayne View Post
    So how are you getting the egr position back to the ecu ?


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    OK, what I have done in explaining type words is put a 5k resistor on pin 1 of the plug into the EGR, another 5k resistor on pin 5, then join the ends of those resistors and put that onto pin 6, that forms a voltage divider and makes the output always somewhere in operating land. Anyway I'm new to Peugeot and just going by what hunches, if I'm on the wrong track then please shoot me down. If someone can provide any info about the additive system I'm powerful interested too.
    Oh and that resistor voltage divider works a treat on the DPF sensor too, that's a real route to better economy, which actually reduces pollution if you think about it.

  11. #11
    1000+ Posts dmccurtayne's Avatar
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    What do you want to know about the additive you can just remove the bag on a bag type system if itís a white tank type you would need to lock the float up to fool it into thinking itís got fluid other than that itís a dumb system it might be easier just to tune out the egr and pef if you are convinced you donít want them


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  12. #12
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    I love a little MAF question. Here's a goodie. Prove that

    d
    dx sin x = cos x
    CEyssens likes this.

    '92 205 Mi16
    '90 Mi16x4

  13. #13
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    Ouch.


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  14. #14
    Fellow Frogger! stew's Avatar
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    RHR needs EGR. Very very complicated


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  15. #15
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    Still no CEL since that small tweak to the MAF output, I'm pretty relaxed about it now.
    I just wish I could do a long drive now as the numbers on the display are lovely now and fill me with confidence of a 1000 km plus range, which it would have had when new but not when I bought it.

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