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+--- Thread: Wanted: pinout diagram and graph of OM603 MAF sensor (/showthread.php?tid=3509)
Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-05-2012
I have pulled the air intake system, including MAF sensor, from a 1987 300SDL (OM603), on the theory that maybe I can utilize this MAF sensor in my 300D for vane control.
In order to rig a controller for the vanes on the turbo, I need to know the pinout and cfm-to-voltage or cfm-to-pulse width graph, whatever it is, for the MAF sensor.
The MAF sensor's MB part number is 000 542 92 14 and the black plastic box into which the four-prong connector plugs is Bosch 0 281 002 024.
Thanks,
Philip
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - aaa - 04-06-2012
What if it's just a potentiometer? There's a spring-loaded flap in there and that's it. Would be easy to just look for varying resistance on the pins.
Why MAF vs using rpm input instead?
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-06-2012
Who says I will be using *just* the MAF as input ;-} ?
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-06-2012
I now have the pinout; you're right, it does appear to be a simple potentiometer. Can anyone give me a clue how many ohms equates to how many cubic feet or kilograms per minute?
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - raysorenson - 04-10-2012
If your pump has a rack position sensor you could use that as a load input.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - willbhere4u - 04-10-2012
I would get a hot wire air flow sensor
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-10-2012
@raysorenson: Thanks for the tip about using rack position sensor as a load input.
(04-10-2012, 08:24 PM)willbhere4u I would get a hot wire air flow sensor
I am of the religion that anything with transistors in my engine compartment is Evil.
Also I'm a little worried about what will happen if I inject methanol, propane, or some such upstream of a hot wire sensor.
But actually, I do have one, from a ...mm, I forget what. Some kind of Mercedes around 3 or 4 liters. Can't lay hands on it right now though, to give you a part number. It's *somewhere* in that jumbled jungle called my garage.
Tight control of the vane geometry under all conditions of load, without bowing to the many curses of Modernity, is my quest my glorious quest...
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - aaa - 04-11-2012
Do you think an exhaust backpressure sensor could play a part?
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - raysorenson - 04-11-2012
Have you considered using one of the megasquirts to control the turbo? They look promising for VNT control, especially if you know how to tweak firmware.
Using airflow to measure load will be a little different on a diesel compared to a gasser. Gassers must keep the air/fuel ratio within a certain range making it easy to assume that if you have X airflow, you must have Y fuel which means Z load. Diesels, being lean burn engines, have a more disconnected relationship between load and airflow. I'm not sure you would have satisfactory results using airflow as the sole or primary load input.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - lgreeley83 - 04-11-2012
I like this thread. Good shit.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-11-2012
(04-11-2012, 05:03 AM)aaa Do you think an exhaust backpressure sensor could play a part?
But of course...
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - olefejer - 04-11-2012
(04-06-2012, 09:26 AM)JustPassinThru Who says I will be using *just* the MAF as input ;-} ?
Hi just want to give you some ideas, by showing the code i have used to control both my HE351VE and now my HE341.
The code is implementet in my gearboxcontroller for the 722.6
I simply have a vacuum valve stock from OM606 constant power max boost = PWM = 100%
No power vanes totally open PWM = 0%
MAF sensor from OM606 has a 0 - 5V output but no idea what the different values correspond to ?
//----VGT Turbo---------------------------------------------------------------------------------------------
egp_raw_avg = analogRead(8);
egp_raw = (egp_raw_avg + egp_raw * 10) / 11; //filter, spikes are supressed
egp_raw = constrain(egp_raw, var_53-15, 1024); // limits range of sensor values to between 0 - 3,5 bar the 307 is = atmosfaric pressure on this sensor
egp = map(egp_raw, var_53-15, 1024, 0, var_54); // map the 0 - 1024 input to 0 - 350 milibar
if(egp > egp_max) {egp_max = egp;} //Constantly keep track of max pressure
//Controlling Delta pressure between EGP and Boost, And Max boost regarding TPS we dont want the EGP to go to higt widthout also Boost rising
if( TPS > 0 && TPS < 10 ) {max_dif_pressure = 20; } // Close vanes at idel to make less noise 20 = 0,2 bar = 3 Psi
if( TPS > 10 && TPS < 50 ) {max_dif_pressure = 10; } // Fuel usage 1 prioty
if( TPS > 49 && TPS < 60 ) {max_dif_pressure = 15; } // Power 1 prioty
if( TPS > 59 ) {max_dif_pressure = 20; } // Never over 35
//Differential EGP - BOOST pressure to high wastegate starts open or VNT opens
boost_reg = 255 - (((egp - ( max_dif_pressure + boost ))) * delta_p_sloope) ;
//Depending on settings var_56 i have different ways to limit boost
if(var_56 == 0){
if (boost > var_25) {boost_reg = boost_reg - (boost - var_25) * 10 ; }
}
if(var_56 == 1){
if (egp > var_25) {boost_reg = boost_reg - (egp - var_25) * 10 ; } //var_25 = max_boost 254 -(100-90)*10 = boostreg = 150
}
if(var_56 == 2){
if (boost > var_25) {boost_reg = 255 - (boost - var_25) * 10 ; }
}
if(var_56 == 3){
if (egp > var_25) {boost_reg = 255 - (egp - var_25) * 10 ; }
}
//----VGT Turbo END
if (boost_reg > 255) {boost_reg =255;}
if (boost_reg < 1) {boost_reg =0;}
//Controlling the vacuum valve on the Turbo
analogWrite(10,boost_reg); //This makes the PWM signal out to pin 10 OF my Shield.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-11-2012
Thanks. On a related note, does anyone know of a turbo shop in the Seattle area which has a flow bench? I'm interested in obtaining flow data for both this air intake system and some intercoolers, and possibly also intake manifolds.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - aaa - 04-11-2012
I'd just get an aftermarket MAF with a manual/chart of what airflows it reads. The wire ones seem to be dependent on intake diameter though.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - aaa - 04-23-2012
I stumbled across something close to what you want in the FSM:
http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Engine/602_603/07.1-1120.pdf
Quote:Testing airflow sensor potentiometer
(B2/1)
Engine off. Detach connector (arrow) from
airflow sensor. Multimeter button Q. Measure resistance between jacks 1 and 3 on airflow sensor.
Readout:
airflow sensor plate in idle position = approx. 50-200 Q
airflow sensor plate fully deflected = approx. 560-1100 Q
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - yankneck696 - 04-23-2012
MAF, MAP, TPS, EGP & EGT all compiled should be able to control it well... Too bad that the last time I talked any machine language was to a Wang 2200 with a 9 1/2" disk drive, cassette drive & PUNCH CARDS....
Ed
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-24-2012
(04-23-2012, 04:37 PM)aaa I stumbled across something close to what you want in the FSM:
http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Engine/602_603/07.1-1120.pdf
Quote:Testing airflow sensor potentiometer
(B2/1)
Engine off. Detach connector (arrow) from
airflow sensor. Multimeter button Q. Measure resistance between jacks 1 and 3 on airflow sensor.
Readout:
airflow sensor plate in idle position = approx. 50-200 Q
airflow sensor plate fully deflected = approx. 560-1100 Q
It's a start! And the ohm readings for the intake air temperature sensor are on page 17...
What was the max rpm at which the OM603 was governed?
Does anyone have a Volumetric Efficiency figure for the OM603?
Should be able to roughly extrapolate airflow versus ohms from those two figures, and thus get the controller initially set close enough to dial it in precisely, from there, by actual field trials using the good ol' butt dyno...
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - sassparilla_kid - 04-24-2012
I'm trying to gather what all you are planning on using to control the vnt, I understand MAF, and possibly rack position? Is there anything else? The comment on your last post about intake air temperature sensor makes me think you may also be using this, possibly since temperature affects air density? Maybe I am just over thinking because it is almost 3 in the morning haha
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-24-2012
Heh...my local turbo guru's tell me I'm overthinking it too. But what these fellows are accustomed to bringing to life are 500-1000 hp Corvettes, Chargers, Mustangs et cetera,...they call an 880 rwhp Charger a "daily driver"...and, to them, a mere 200-250 hp old Mercedes diesel seems like a rather quaint folly. So far, though, as long as I can whip cash out, they're willing to humor me.
My plan is to craft-up an Arduino-type controller at first. With exactly the inputs yankneck lists, plus boost of course, maybe rack sensor and rpm also, implementing something along the lines of olefejer's algorithm above --I am after perfection, both while accelerating *and* decelerating. But then, after I get it dialed-in, my aim is to duplicate the functions of the electronic controller with as close to purely mechanical controls as practical.
I did have differential calculus under my belt already when I graduated high school in 1972, and am from an earlier life an accomplished database programmer --I've written entire library tracking and hotel reservation systems, single-handedly--, so there's nothing here mathematically or computerese-wise beyond my ken. But it's just hand-waving up til now, and is going to take shape *very* slowly. I don't expect to be space-cowboy'ing Toyotas and older Beemers until September at the earliest. Too many other non-car commitments. Cash is running low at the moment, too...
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - raysorenson - 04-24-2012
A 6.4l powerstroke can make 40 psi at 30% load and 100% load. That's not keyboard tuning. I can hop in one of the many so equipped trucks on the lot right now and observe load vs boost in the shop's datalogger and see it. There is a massive disconnect between airflow and load in a VGT/VNT equipped turbodiesel.
I don't see how using airflow as a primary load input will accomplish anything other than putting the turbo in a feedback loop.
I'm giving advice as someone who is involved in a small and simple engine control project myself: K.I.S.S. Keep It Simple, Stupid. Figure out how much fuel you've got then ballpark how much boost you'll need. Then log data and play around with boost until you're in a good range of fuel/boost ratio. Get elaborate after you're on the road with a working prototype.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 04-24-2012
(04-24-2012, 12:10 PM)raysorenson ...A 6.4l powerstroke can make 40 psi at 30% load and 100% load...There is a massive disconnect between airflow and load in a VGT/VNT equipped turbodiesel...Get elaborate after you're on the road with a working prototype.
That's the same thinking as I get from the turbo shop. But, for a combination of reasons, I don't plan to take boost much above one bar. Just, I want that one bar, and the fuel to go with it, available in a lower part of the rpm range than the stock system delivers it. Fueling will be only about twice stock. At this relatively small power level, control finesse will have to substitute for brute force. Thus my interest in MAF, especially in the scenario where the car is coasting, decelerating, coming up to a stoplight, and the light suddenly turns green and I decide I need to floor it. Since it takes about 10 nuts and screws to take off and put on this air intake, might as well engineer-in the capability to use MAF, whilst it's conveniently off the car.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - aaa - 04-24-2012
I thought you were just interested for research purposes. I don't see how it would help as a direct input. Logging the results and using them to improve a a map based off more useful inputs is what sounded handy to me.
Control finesse = pedal position input. Seems to be the thing most directly related to desired acceleration.
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - Hario' - 05-03-2012
I now have the pinout; you're right, it does appear to be a simple potentiometer. Can anyone give me a clue how many ohms equates to how many cubic feet or kilograms per minute?
I'm just browsing but.. MAP only reads air pressure above absolute zero, by cross referencing against air temperture, the ECU calculates air density, nothing do to with air volume?
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - raysorenson - 05-03-2012
(05-03-2012, 03:06 AM)Hario Can anyone give me a clue how many ohms equates to how many cubic feet or kilograms per minute?
Vane air flow sensors measure velocity not mass so you won't be able to get a KG/min measurement without cross referencing air temp. CFM is only a measure of velocity. You could push the door open with a blowtorch but there would be very little mass flow rate compared air pushing the door open the same amount at ambient temps.
Quote:I'm just browsing but.. MAP only reads air pressure above absolute zero, by cross referencing against air temperture, the ECU calculates air density, nothing do to with air volume?
Corrrect. To make the leap from density to mass flow the ECU must cross the density calculation with volumetric efficiency at the current RPM.
I'm beginning to feel like I'm in a gasburner forum
RE: Wanted: pinout diagram and graph of OM603 MAF sensor - JustPassinThru - 05-03-2012
Aha: found the VE chart et cetera, at www.w124performance.com. I gather that max governed rpm is 5250, and VE at 5250 is 70%, at 1900 is 95%. You devils are going to make me do all the work, aren't you