is this a bad maf wiring fault ? ecu ? any help, thank much

piconewtrain · Post by **piconewtrain** » Tue Jun 19, 2018 1:38 am

Can anybody provide me maf sensor wiring diagram please ! volvo s40 1.6d edrive 59 plate
troubles : sluggish at the low rpm lacking power . fuel consuming .
engine hunting at 1900 rpm it was at 3000 rpm ..when it is hunting . every thing changes , fuel pressure , maf , egr ,everything fluctuating ...i found out that when the maf sensor air comes in around 35kg/h at idle [ it is actually when egr closed off maf value is 35kg/h ] it will not hunting . and now at idle maf sensor air value is around 20kg/h
history with this car new dpf installed and egr as well .
No code on dashboard
i am confusing on maf sensor wiring . it s a 4 wire maf . key on engine off , i took the connector off the maf sensor ,it is reading as follow : 0 v , 5v ,0 v ,12v. and now put back . 0v, 3v, 0v, 6.5v.... i thought that 12v, it is a constant 12v it shoudnt change , am i right ? or is that 12v it is a signal as well ?? i checked the wiring it fine no broken or split .
any wiring diagram,input ,suggest ,help . really appreciated . thank

Tronic · Post by **Tronic** » Wed Jun 20, 2018 12:44 pm

H piconewtrain!

Nasty fault!

Could you please tell me if you had your DMM's black lead to battery minus in both measurements.

Regards

Bjorn

piconewtrain · Post by **piconewtrain** » Wed Jun 20, 2018 9:23 pm

Hi what a surprise a Volvo er , thank you very much any way .
These measurements I took , I indeed placed the black lead on the negative .
I am afriad it is going to be ecu fault . I hope just wiring problem . 4 wire maf sensor . Should be two signals( 5v) one ground and one 12v this one shouldn't change much because it s a supply . In my case only one signals 5v and one ground available . Any one has the wiring to ecu ?? Thanks ..

Tronic · Post by **Tronic** » Thu Jun 21, 2018 8:20 am

Hi Piconewtrain!

Volvo’er!

I am indeed from Sweden, but really, no Volvo fan.

That was a creepy one! Yes, both power feeds, 5 and 12 volts, should be stiff.

There is no way you could have a voltage drop of 6 volts measured at the MAF connector, connected to MAF, unless there is a measurement error, wiring problem or a bad connection somewhere between 30 and the MAF. The thing here is that the 5 volts drops to 3 with the MAF connected, thinking of the MAF’s current draw, see below (2). If it were only for the 2 volts drop on the 5 volt supply, absolutely yes, I would also start to think about a faulty ECM if all other measurements was done in order to eliminate such things as bad power to the ECM, wiring and a few other things.

1. There must be an enormous current draw by the MAF to create a voltage drop of 6 volts in the wiring and in that case the wire would get hot and melt, but hopefully fuse F35/10A would blow.

2. Since both 5 and 12 volt drops I think there is a common fault. I would check the main relay which feeds 12 volt to the ECM. If you have voltage drop across relay K46 that feeds the ECM, both 5 and 12 volt will drop. So, why would also the 5 volt feed drop? When the power (12V) to the ECM drops below a certain value, the ECM’s internal 5 volt supply cannot manage to regulate the 5 volt feed.

3. As you see in the wiring diagram (sorry, our Volvo Vida is unfortunately down at the moment but hope this one is okay) the 12 volt goes from 30 to F9, main relay K46, F36 and finally to ECM pin 24 and 7. If you look at the wiring diagram you can see that there are 4 actuators – as well as your MAF, ECM and some other things - that will be affected if the voltage drops across the main relay and since they draw a fair amount of current, the 12 volt will drop and your engine will go crazy. One thing more, have you checked if both battery pole terminals are in good connection with the battery and that was also the reason I asked about where you had your black test lead? Sorry, had to ask…

Why the voltage drops when you connect your MAF is a mystery though...

Well, that was lots of theory, but I think it is a good start or I have missed something.

Regards

Bjorn

piconewtrain · Post by **piconewtrain** » Thu Jun 21, 2018 5:25 pm

hi . That is a lot of info. It is mystery indeed voltage drop on feed and signal At sametime .. any way the diagram you posted . Is it right for the car ? Is it possible 12v also comes from ecu .,? And one thing missing here is the other 5v . 4wire maf sensor built with intake air temperature Should have 5v 5v and ground and 12 v. But in my case only one 5v available . So ... that is direct pointing to ecu isn't it ? '... I think I might open up that bunch of electrical wire and trace it up to ecu .. if I cant find diagram ... thanks

Martinjensen · Post by **Martinjensen** » Fri Jun 22, 2018 5:37 am

Hello Piconewtrain.

If you could PM me the VIN i will look in Volvo Vida for the wiring diagram.

Regards Martin

Tronic · Post by **Tronic** » Fri Jun 22, 2018 9:59 am

Hi Piconewtrain!

Best thing is to get right wiring digram which Martinjensen kindly offer, the one I posted was from Autodata and both were just about the same for the D4164T and D4162T 1,6D DRIVEe engine. Non of them feed the the 12 volts to the MAF from the ECM, it goes from 30 (battery +) through the main relay K46 to F35 in one engine and on the other F32. Power to the ECM uses F36 in both.

Piconewtrain, I may have the wrong engine since you did not specify what year model, but safest is to wait for Martinjensens Volvo Vida diagram. When you get that one your problem will most probably be solved by a few measurements.

I am still pointing to, if not Autodata serves me wrong wiring diagram, a bad connection between 30 and the MAF or/and ECM.

Our Volvo Vida is up again. We had problem with the Bluetooth driver for the TDK stick in W10 which sadly happen quiet often and we have not yet got any working solution for this from Volvo Cars in Gothenburg... If anyone has a solution for this I would be more than happy if you could share it with me, but please, via PM since I do not want to clutter Piconewtrain's thread.

Regards
Bjorn

volrem · Post by **volrem** » Fri Jun 22, 2018 10:01 am

This MAF doesn't have 5V feed from ECM. It uses only 12V from fusebox. Ground is from ECM, MAF signal is digital and fourth wire is for air temp.

Tronic · Post by **Tronic** » Fri Jun 22, 2018 12:05 pm

Volrem, thank you for clarifying!

Well, then the 12 volts drop is what to be worried about and in worst case - again if my diagram serves me right information - it could as well affect the power feed to the ECM, it all depends upon where you have a bad connection in the chain.

We will wait until Martinjensen gets back with right wiring diagram, no need to guess. Sorry for the earlier huge text mass that may have messed things up...

Regards
Bjorn

Martinjensen · Post by **Martinjensen** » Fri Jun 22, 2018 2:28 pm

Diagram and ECU Pinout information sent.

It is exactly as Volrem said:

This MAF doesn't have 5V feed from ECM. It uses only 12V from fusebox. Ground is from ECM, MAF signal is digital and fourth wire is for air temp.

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