Kia Sedona Ex 2.9 CRDI 2006 MAFS sensor readings strange numbers!

So I have a Kia Sedona 2.9 CRDI and the last years it´s been a bit strange regarding performance on the road and also at idle. Error codes of different kind have come and gone after some repairs but p0101 and p0103 have remained. This summer I did some work on the fuel and air intake system in order to find out more. New fuel filter, cleaning and repair of the diesel injectors, removal and refitting of the air intake system from filter to intake manifold.

After this the car was like new again...for a week. Then the p0101 appeared again. Eventually I bought a new MAFS but the code returned. I cleaned the ground point at the car chassi (front left side). Next I measured the voltage, resistance and frequence on the MAFS harness with a T-pin. A bit confusing data...for me at least.
Pin 1, color brown/pinkish, should be 5V (DC) was 14 V (MAFS)
Pin 2, color black, (ground) should be max 0,05 V (analoge) was 0,08 V (MAFS)
Pin 3, color blue, should be 0-2 V (DC) at idle was 2,79 V at idle (MAFS)
Pin 4, color green, should be 0-5 V (analog) at idle was 2.028 V and 19,2 Hz (IATS)
Pin 5, color white, should be ? was 9,33 V and 2628 Hz (IATS) (I do not find info on this pin in the workshop manual)

The numbers on "should be" are from the workshop manual by Kia.

So I´m confused that the reference voltage should be 5 V and is battery positive voltage at 14,12 V. Pin 3 does not change in voltage when the rpm is changed and no voltage wave or frequency can be seen. I belived that pin 4 and 5 are the IATS signals.

Quiet often I cancel the error code (P0101) and then the car runs perfect for one or two turns. Then it gets slow again with increased fuel consumtion if we drive on. If we stop and start again the car often runs perfect again. I´m thinking some glitch or minor electrical error since the car most often runs perfect.

What do I miss here? I have started to check the cables between the MAFS harness and ECU, ground etc. Have not made it all the way though.

I use Icarsoft CR elite and a waveform multimeter with ok quality to measure data on the car.
Some indication on what could be wrong would be nice

Does the MAF PID increase with rpm on your scan tool? And does IAT show ambient temp with the engine cold?

I think the connector pin-out, and expected values, may be wrong. If it's from the P0101 pinpoint tests take a look at the engine controls wiring diagram to see what it shows. Pin 5 looks like it might be a MAF frequency signal. Could try increasing rpm to see if the frequency increases.

Well the temperature reading seem to be ok with IAT 20-25 or so degree C. The air mass flow reading is constant, last time 2 g/s when the car runs badly. Then I stop the car and start again with a reading of MAF from 10 g/s at idle and up to 180 g/s or so during a test drive.

Also the frequency at pin 5 changes with rpm correct. As you wrote the scan tool says readings are out of expected range.

Not expert at all on diesel engines but I see those maf readings too low.

Here are some PID's of my mothers Sedona (not sure whether is 2.7 or 2.9). Anyway, Maf readings are higher.

If air flow is not coming from intake manifold, then could be coming from EGR, isn't it?

Regards.

Not sure on the Diesels but I've heard that aftermarket Hyundai/Kia MAFs often don't work right out of the box. The OE is expensive but required.

I use the same brand on MAF as the original from KIA. That should no be an issue then...I think at least!

Thanks a lot for the readings! I didn´t see the attached pictures at first glance at the post...

I´ve disassembled the air intake from the air filter box and all the way through the EGR and finally as the air enters the engine. Taken a part everything, checking for broken parts, cleaning, new gaskets etc. The air intake hose between the MAF and the EGR was broken so that was one of the first things I repaired.

So when everything is working the car runs perfect, for beeing a KIA Sedona It has some 240 turbodiesel horsepowers and is quiet a big and heavy family car...in swedish proportions and not US standards! I believe you guys have bigger cars in general and we have more expensive fuel (Diesel cost about 1.75 US dollar/litre in Sweden right now and in the US about 0,6 US dollar/litre?). A highway drive with the KIA and when it´s reading OK values from the MAF the fuel consumption is about 0,75 litres/10 km. When the MAF readings are wrong the fuel consumption goes up to 1,2 or so litre/10 km. Only difference between the scenarios is a stop and start.
During a good drive the readings looks a lot like the one you posted guafa.
Thanks again for your posting!

Hi Mikael
Jag tar detta på svenska. Vad kom du fram som var fel på din Carnival? Jag har en med samma symptom.
// Jan-Åke


Translation:  I take this in Swedish. What did you find wrong with your Carnival? I have one with the same symptom.