MAF voltage too low

Brian Owner/Technician Iowa Posted   Latest  
Unsolved
Driveability
2006 Volvo XC70 2.5L (59 B5254T2) 5-spd (AW50/51 AWD) — YV4SZ592161219386

I have a 2006 Volvo that at an idle can only get the MAF to 1.37 volts at idle at operating temp. It does change as should with engine speed. No drivability issue only check engine light. Sets codes 121B and 120D. Verified no air leaks by smoking intake and using bullseye no charge air leaks. The fault will not set immediately it takes 4-5 drives. Replaced multiple MAF sensors did have a couple failed ones. Even using OEM Volvo voltage is too low. All passages in oil separator clear. Power and grounds to sensor are good. Verified no restriction in charge air cooler by running MAF directly to Throttle body same voltage. Has anyone had similar issues? It seems the MAF sensor is not capable of the correct voltage. Car has 225K on it. Runs great. 

Did I miss something? Thanks!

0
Larry Owner/Technician
California
Larry
 

Check your throttle angle. Dirty throttle body will set maf codes… (nice, huh?)

0
Ð Awarded
Brian Owner/Technician
Iowa
Brian
 

Yes Thanks did that also. I failed to inform you of that one.

0
Ð Awarded
Juan Diagnostician
California
Juan
 

I had a similar issue a while ago and my fix was the OE maf from the dealership y tried 3 different brands and code come back

0
Ð Awarded
Glenn Owner/Technician
Texas
Glenn
 

Make sure of no air inlet restrictions, I've seen trash bags sucked into inlets before. If the owner is using a K&N high flow filter, suspect oil film on the MAF hot wires. Clean with MAF cleaner of brake spray DO NOT use carb spray. Use only a dry air filter on these. Make sure throttle body is clean. Other item listed is possible corroded contacts for the MAF or damaged MAF.

0
Ð Awarded
Larry Owner/Technician
California
Larry
 

Have you cleared the adaption by disconnecting ecm and then turning key to pos 2 and letting it sit for minute or so? (or using everybodys favorite software ViDA?

0
Ð Awarded
Marlon Owner/Technician
California
Marlon
 

Check crankcase pressure. Sounds like pcv oil separator under intake is plugged. Should be 1-2 inches h20 of vacuum at idle. Also make sure to clean manifold vacuum banjo bolt or replace .

+2
Ð Awarded
Agree
Darren Mechanic
Wisconsin
Darren
 

What is gps at idle?

0
Ð Awarded
Steven Mechanic
Washington
Steven
 

How are you determining that 1.37 volts is too low? Is the fault setting at idle or cruise? I suggest a volumetric efficiency test, and check the fuel trims at idle and cruise. That could help in determining if it is a problem at idle or not.

+1
Ð Awarded
Agree
Robert Owner/Technician
Massachusetts
Robert
 

if you have a good scan tool there should be a mass air flow correction pid and crankcase pressure/ vacuum affects this pid as it will try to correct the problem much like fuel trim, I have also seen many throttle bodies cause a rolling idle, wiring can be an issue as well as only using an OE maf sensor, real important on Volvo, do you check crankcase pressure through the dipstick tube running…

0
Ð Awarded
Tony Owner/Technician
Missouri
Tony
   

This is a Ford era Volvo. I don't know anything about your vehicle but certain Ford powertrain platforms, particularly ones with conical air filters, suffered problems with non-OEM design or even poorly copied aftermarket replacement filters. It had to do with laminar flow and was critical to that design otherwise breathing measurements would be off and cause codes.

0
Ð Awarded
Adam Technician
Minnesota
Adam
 

I realize Volvo shows 1.7V for the engine idle spec, but i have found that to be out of line compared to known goods. Your 1.3-1.4V sounds just about right. There is already lots of good advice here, I will add two things that are less common but will cause MAF codes…bad throttle body (not just dirty) or issues with the wiring to the potentiometers in the throttle. Regards,

+1
Ð Awarded
Interesting
Paul Technical Support Specialist
Colorado
Paul
 

What are you using to flash the new throttle bodies? Vida?

0
Ð Awarded
Larry Owner/Technician
California
Larry
 

Hey Brian, Did you ever resolve this?

0
Ð Awarded