Ohm specs for 355 Motronic 5.2 MAF sensor?

I would like to know too...

 

That $20 book may have the answers you are looking for.

http://www.amazon.com/Bosch-Fuel-Injection-Engine-Management/dp/0837603005
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The voltage for the fuel injectors passes through the 348 MAFs. Lower the MAF resistance and the 348's fuel injectors receive higher voltage (which means that they open wider so you'll run richer).

The 348's ECUs control how long the 348 fuel injectors are open, but the MAFs control how wide open they go.

It's effective, but it's an analog solution that harkens back into the 1980's.

That being said, you could still probably rig a circuit to raise or lower the voltage to the fuel injectors on 355's to get the same effect, easily...without a lot of drama.

No need to go through the 355's MAF to do so, either...going straight to the fuel injectors would work better and easier, in fact. You just need a higher input voltage and an adjustable resistor...commonly available.

 

Sounds like a good plan.

On the 348, each MAF has two entirely different circuits:
1 circuit measures airflow/temp in the engine air intake
the other circuit influences the voltage that opens the fuel injectors


I'd think that you'd want to know if the 355 single MAF has both of the above circuits, and if so, would want to calibrate both of them independently.

 

Basically, It doesnt matter because the computer trims to the 02 sensor(s), not the amount of air.

I can't explain why replacing one afm with an identical part number would increase performance. There are other substitutions that increase hp, but I've never experienced any change with apple apple substitution.


Jay

 

O2 sensors are ignored at full throttle.

 

How much misinformation can a person absorb?

The fuel quantity is a function of injector duration, ie time, not by how wide open they go. Please try to avoid confusion by giving proper explanations, they are plainly written in the w'shop manuals.

 

The information that I gave above is accurate, as shown in Ferrari's 348 fuel injection schematic, workshop manual, and Motronic 2.7 programming code.

The whole reason that adjusting the resistance on the M2.7 MAF modifies CO is that resistance controls the voltage delivered to each fuel injector. In turn, the voltage controls the speed and depth of each fuel injector opening. This is why the Ferrari 348 Workshop Manual refers to the MAF resistance as the CO adjustment screw.

On the other hand, the programming and fuel maps inside each Motronic ECU control how long each injector is open.

 

I had no doubt that you would argue about this!

The ECU/chip/fuel map switches the ground signal to the injectors, the duration of that ground determines the time of injector opening, voltage to the injectors is not flucuated as you could lead others to believe. Time of opening is influenced by air flow (measured va the MAF),coolant temp, engine speed, throttle opening (I think that's all I recall from my Bosch training)

 

It's true that the ECU/chip/fuel map controls how long the injectors are open, but you are forgetting that the CO screw on the MAFs actually has a real function (that being: controlling the actual voltage that reaches the injectors).

Voltage is just as critical to the injectors as timing.

In fact, the ECU/chip/fuel maps adjust to longer timing durations for the injectors if your system voltages are low (e.g. low battery, alternator not fully charging, etc.).

 

So you believe that the MAF reading directly influences the voltage to the injectors? You believe that miniscule voltage adjustments are being made at the injectors which limit the range of opening of the pintle in the injector?

By your reasoning, one could control say...the fuel door release flap, by applying a smaller voltage? Seems to me that when sufficient voltage appears, the solenoid operates. Full stroke, period. Please explain how one can expect an injector to operate differently, X volts operates it, period. X being around 5.0v.

 

Hello F355spider, here is a link of a suplier of MAF sensor.
There is a list of others cars that could have same sensors
Hope it could help.
Nico

http://cnhchcar.en.alibaba.com/product/200017256/200556043/air_flow_sensor/air_flow_sensor_0280_213_012_.html

Detailed Product Description


Relative Number: 0280 213 012

It fits: 0 986 280 110

OEM Number: 154916

88 27 429

91 13 846

30539175

3517569

8602793

HONGCHUANG NUMBER: A45-13000

Suit For: FERRARI/SAAB/SCANIA/VOLVO

Ftts the following models:

FERRA 456 GT 5.5 (F116) 01.93

SAAB 9000 2.3-16 Turbo 09.90-08.93

SAAB 9000 Hatchback 2.3-16 Aero CS 02.93-12.98

SAAB 9000 Hatchback 2.3-16 Turbo 09.90-12.98

VOLVO 740 Kombi (745) 2.3 Turbo 08.89-07.90

VOLVO 960 (964) 2.0 08.90-09.93

VOLVO 960 (964) 2.9 08.90-07.94

VOLVO 960 II (964) 2.9 07.94-12.96

VOLVO 960 Kombi (965) 2.0 08.90-09.93

VOLVO 960 Kombi (965) 2.9 08.90-07.94
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That's incorrect.

What do you think the factory-adjustable MAF resistance does to the Ferrari fuel injection circuit?!

 

I have a datasheet of the MAF we have in the 5.2 F355. I can confirm that it is not adjustable and that there is no resistance measurement which is possible to diagnose it. PM me if you want a copy in pdf format.
You can have an idea of how far you are from calibration if you look at the "Long Term Fuel Trimming" parameters using an OBD2 reader.
This parameter is learnt by the Motronic when your engine runs in closed loop. It tells, based on O2 sensor reading, how far the Motronic needs to correct the map which are stored in its memory. Even if the O2 sensors are not used at WOT, the "Long Term Fuel Trimming" still corrects fuel injection based of what was learnt while in closed loop mode.
If your MAF is out of calibration, the Motronic will see it because it will have to correct the base-map looking at the O2 sensors, and you will see a similar drift of both banks. On the contrary, if you have a failed pressure regulator or bad injectors on one bank, the LTFT parameter will drift on only one side of the engine.
This self-compensation capability of the 5.2 explains that, except if you are far from the original tuning (more than 20% on LTFT), there will be no extra power changing a slightly bad MAF or slighly bad FPR.

 

A much more eloquent and informed response to the original question. Thank you for posting accurate information which no doubt will fall on some deaf ears.
Thanks.

 

Different systems. Accurate for Motronic 5.2, not accurate for Motronic 2.7 (e.g. 1995 355's).

M5.2's have no CO screw on the one MAF. In contrast, M2.7's have CO adjustment screws on both MAFs.

 

Sorry more misinformation, only the 2.7 used on the 348 has a CO adjustment the 2.7 355 does not. Thanks Bowbell and Eric355 for correctly
telling us what my Bosch Manuals state.