Volvo

Have Volvo questions? Ask a Volvo mechanic for answers ASAP

Ask an Expert,
Get an Answer ASAP!

MAF sensor problem on C70 2004 2.4T, car now start but does…

Customer Question
MAF sensor problem on...

MAF sensor problem on C70 2004 2.4T, car now start but does not run properly, new BOSCH MAF fitted, no change. Nearby repairman say MAF reads 1000 kg/s (more than 10 times too much).

Mechanic's Assistant: Does the engine stall right after starting? And what about hesitation or jerking during acceleration?

Car was working with problems for 50 miles, then stoped on motorway, and no more starting. Then two days of sun and car started again. It does handle idle or few meters, no hesitation, no jerking.

Mechanic's Assistant: Are you fixing your C70 yourself? What have you tried so far?

Three repairman did not find the problem, no ODBC2 code. I can do some stuff, I did change the MAF myself, and tried new camshaft and cranckshaft sensor (but did not change anything so have put back the old ones).

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

No, I can pay for good advise...

Submitted: 21 days ago.Category: Volvo
Show More
Show Less
Ask Your Own Volvo Question
Customer reply replied 21 days ago
I also cleaned the main battery ground point (under battery) but no change.
Answered in 18 minutes by:
5/29/2018
Volvo Mechanic: Danny, ASE Certified Technician replied 21 days ago
Danny
Danny, ASE Certified Technician
Category: Volvo
Satisfied Customers: 4,474
Experience: ASE Master Technician with L1 advanced engine performance, VW Certified, former US Army mechanic
Verified

Do you have a scan tool capable of reading real time sensor values? I'd like you to verify that mass airflow sensor volume for me. I don't think it's possible to read 1000 grams per second, for one it would through a fault for implausible signal, and it'd probably then ignore that reading, for two....yeah I just don't think it's possible for it to read that high, that indicates a potential wiring issue. I can walk you through testing it.

https://www.amazon.com/Scanner-OBDATOR-Wireless-Diagnostic-Android/dp/B074DX2N2Z/ref=sr_1_10?s=automotive&ie=UTF8&qid=1527623024&sr=1-10&keywords=obdii+elm327

These are nifty devices, you use a free app from the app store and you can then get me the MAF readings and other values I'll need to diagnose the problem. Otherwise, if you have a scan tool let me know. We need to verify that maf reading, then unplug the maf completely and see if a reading shows up on the computer then, and let me know what it is at idle, and at 2000 RPM with the vehicle stationary. See if the terminals in the maf connector are splayed, they should be nice and tight, if the prongs are spread open for each wire, it could be causing high resistance and causing this.

Ask Your Own Volvo Question
Customer reply replied 21 days ago
Already changed the MAF sensor, a repairman came with two different computers able to read real time sensor, one read before the change and one read after the change - exactly the same reading with the two computers.
Before buying the new BOSCH MAF (with BOSCH security seal), I even tried another second hand MAF (second hand from a working car) which was reading exactely the same crasy flow.
I have myself a small and cheap ODBII reader, but I cannot access real time data. It does not seem any of the MAF are faulty, and the contact/connector look perfect, 12 volts arrive on battery pin. Read of sensor looks like 11 volts instead of what should be arround 2 volts... I was suspecting a ground problem, that is why I cleaned the main battery ground point - no change...
Customer reply replied 21 days ago
If one unplug the MAF meter, the engine stops immediately.
Volvo Mechanic: Danny, ASE Certified Technician replied 21 days ago

I understand that they read it, but here's the thing, they weren't good enough to fix it, so I can't rely on what they told you. We need to actually vertify and test things. When you remove the maf connector, often it should default and insert what the engine SHOULD be seeing for airflow at that rpm and temperature, generally when you disconnect a maf and it dies, it means the Maf is actually good. The MAF is the main sensor used for fueling, the fuel injector pulsewidth is directly calculated from it, your injectors would be stuck open all the time at 1000 kg/sec you'd be trying to fuel something like 10 kg sec of fuel. It doesn't make any sense, in 18 years of experience I've NEVER seen it, it indicates a faulty ECM if that's the case, but I need to know numbers, and not just the MAF, other numbers too.

Are you sure your meter can't read live values? What's the model number of that meter you have? It's pretty standard. If not you'll need to buy that bluetooth dongle.

Ask Your Own Volvo Question
Customer reply replied 21 days ago
I was there for one of the measurement, the computer clearly displayed unbelievable value, I know you cannot get that amount of air through that tube, and without any abnormal noise - just at idle (measurement reduce a bit at high RPM). My ODBII is too old and too cheap ($15 few years ago), it would take time to get another one. Anyway it is in accordance with what the voltmeter gives: 10 Volts on the sensor pin (whatever RPM) instead of arround 2 volts (other pins: stable 5 volts, battery and ground, one unconnected). I have just checked and the engine does start with unplugged MAF, engine just stops when you unplug MAF sensor while already running.
Also I think it is important that the car refuse to even start for few days (no a single explosion), it took few very warm days to get it to start (nothing touched in the car during those few days), and now it starts no problem.
Volvo Mechanic: Danny, ASE Certified Technician replied 21 days ago

Right it's not just about only that though, it's also about what happens to other values. I need to see how they react to each other. For example you mention temperature, quite possibly the coolant temp sensor could be at play.

You can buy that ELM327 for $15 dollars, you need to do so. I need to see how the ratings react, it's not about a voltmeter, a the voltmeter isn't specific enough. It's about how other numbers react WHEN certain things are done. What's the short term fuel trims, what's the long term fuel trims, when the values are plugged in by the ECM, do the fuel trims settle down, what do the oxygen sensor values look like, what's the ignition timing. You CANNOT diagnose this with a voltmeter. Amazon prime carries those Elm327 devices you could have one maybe even still today if you get on and order it now or in the morning.

I understand you don't want to bother, trust me 15 customers a day try to do this, but here's the thing, it's not a carburated 74 with points ignition, you cannot diagnose this concern with a voltmeter. Well you could, but its going to cost you a ton of time and money in parts you throw at it. We don't buy scan tools for fun. My BMW and Porsche tool was 25 grand, you think I'd buy that if it wasn't absolutely necessary?

If your meter is reading 10v, but yet the commputer says 1000 grams per second then that would likely mean your engine control module is faulty, but I'm not going to have you find a used module then spend 200 dollars having it programmed to the immobilizer without first seeing the numbers myself and seeing if they look plausible. You simply need the right tool for the job, and in this case that's an EXTREMELY inexpensive bluetooth device and a free app.

Sometimes, a sensor will rea correctly the majority of the time, and the signal will drop out for a fraction of a second, a digitial meter can't catch that, real time values being graphed CAN.

Ask Your Own Volvo Question
Customer reply replied 21 days ago
OK, i will order a new ODBII reader, but living in the UK it will take a bit longer. I cannot get that brand here (unless waiting for more than a week), any advise from such a list: https://www.ebay.co.uk/sch/i.html?_from=R40&_nkw=Car+Wifi++OBDII++OBDATOR&_sacat=0&LH_PrefLoc=1 ?
If not I will just get one looking at descriptions...
Volvo Mechanic: Danny, ASE Certified Technician replied 20 days ago

I just went to Amazon.co.uk and typed in Elm327 and there's a TON of them available on prime, you don't need that exact one I showed you. Find the cheapest elm327 bluetooth adapter available on prime and order it on Amazon so you'll have it quick.

Ask Your Own Volvo Question
Customer reply replied 19 days ago
OK, got one, tried the first Android app advised with the product, just shows me the codes; tried the second app proposed, do not connect (whatever option). Which app do you suggest in "you use a free app from the app store"?
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a volvo mechanicLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Danny Your Own Question
Danny
Danny
Danny, ASE Certified Technician
Category: Volvo
Satisfied Customers: 4,474
4,474 Satisfied Customers
Experience: ASE Master Technician with L1 advanced engine performance, VW Certified, former US Army mechanic

Danny is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

The nearest Volvo dealer is 160 miles away. Best $15 bucks I have spent in a long time!

Paul MCorpus Christi, TX

I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry.

Stephanie PElm City, NC

used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future.

David L.Richmond, TX

9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much.

PhilMarysville, CA

Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible.

CharlesWalnut Creek, CA

As a single woman, I really appreciate an excellent and affordable opinion.
Thank you Geordie, I will not hesitate to contact justanswer in the future!

SueCharleston, WV

Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff.

JimCastleberry, FL

< Previous | Next >

Meet the Experts:

Enes

Enes

VOLVO Master Technician

4,911 satisfied customers

18+YEARS WITH VOLVO AS THE MASTER VOLVO MECHANIC&Ase

Andy

Andy

Volvo Expert Technician

3,740 satisfied customers

One of only a handful of ACTUAL Volvo dealership technicians on JA, ASE Master Certified with L1

volvoexpert1

volvoexpert1

ASE Certified Technician

1,001 satisfied customers

Volvo Master Technician with 15 years excusively with Volvos. Also ASE L1certified for over 10 years.

dramey

dramey

ASE Certified Technician

669 satisfied customers

have worked on volvo's for 4 years and am a ase master mechanic. current shop foreman

Chris (aka-Moose)

Chris (aka-Moose)

Technician

550 satisfied customers

16 years of experience

Tim Mohr

Tim Mohr

ASE MASTER TECH

521 satisfied customers

30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL

Jim B

Jim B

ASE Certified Technician

504 satisfied customers

40 years Import and domestic AAA Approved Shop owner 30 yrs

< Previous | Next >

Related Volvo Questions
Alarm screen "Charging failure service urgent". Car did not
Alarm screen "Charging failure service urgent". Car did not die. Had it delivered to dealer who replaced alternator and bearings. Had the same alarm screen after the work. Dealer pulled "Radiator tamp… read more
HondaPlatinum
HondaPlatinum
High School or GED
148 satisfied customers
Volvo S60 2.5T AWD: climate control problem - heat works 50%
climate control problem - heat works 50% of time. when not heating, I can shut off the engine, restart and it heats up fine. sometimes heat temp is too hot, temp fix of restarting is same. adjusting t… read more
Andy
Andy
Volvo Expert Technician
Vocational, Technical or Trade Scho
3,740 satisfied customers
major oil leak on passenger side of 98 v70, 20 valve engine.
major oil leak on passenger side of 98 v70, 20 valve engine. can't tell where it's coming from. not drain plug or oil pan bolts. leaks faster when running. how do i remove cover of timing chain. we ju… read more
Andy
Andy
Volvo Expert Technician
Vocational, Technical or Trade Scho
3,740 satisfied customers
Volvo V70 2008. I just checked the tyres, oil and coolant
Volvo V70 2008. I just checked the tyres, oil and coolant prior to a trip tomorrow. Then when I try and start it nothing seems to work and all sorts of warnings are coming up. Can't operate the parkin… read more
Enes
Enes
VOLVO Master Technician
Vocational, Technical or Trade Scho
4,911 satisfied customers
The oil and water is mixing together inside of The coolant
The oil and water is mixing together inside of The coolant tank but it's not inside the oil part and the head gasket is not blown … read more
Dan
Dan
Dealership Technician
Associate Degree
2,056 satisfied customers
Overheating problems, everything is fine with coolant and no
overheating problems , everything is fine with coolant and no leaks. Fan comes on TOO LATE and engine feels too hot and unbearable when hood is popped open… read more
Expert
Expert
30 satisfied customers
Overheating. No leaks and coolant is fine. 2002 volvo s80.
overheating JA: Have you checked the coolant? Have you checked for a leak in the cooling system? Customer: no leaks and coolant is fine JA: What is the model/year of your Volvo? Customer: 2002 volvo s… read more
Pete
Pete
Independent Auto Technician
Vocational, Technical or Trade Scho
138 satisfied customers
Drove car without coolant and it started smoking. Replaced
Drove car without coolant and it started smoking. Replaced coolant, but now car won't start and oil light is on.… read more
kalamykid
kalamykid
Pactor automotive
Vocational, Technical or Trade Scho
97 satisfied customers
No heat. Coolant level is ok thermostat seems to be working
coolant level is ok thermostat seems to be working the temp gage is operating ok … read more
Pete
Pete
Independent Auto Technician
Vocational, Technical or Trade Scho
138 satisfied customers
After testing the coolant pressure for leaks, there is
After testing the coolant pressure for leaks, there is air/coolant coming from the oil pan gasket in the middle facing the firewall. … read more
Chris (aka-Moose)
Chris (aka-Moose)
Technician
Vocational, Technical or Trade School
550 satisfied customers
Coolant is flowing out of the bottom of the engine
coolant is flowing out of the bottom of the engine compartment near where the radiator must be f … read more
sprinkles08
sprinkles08
Technician
High School or GED
11 satisfied customers
Just had the red triangle, low coolant, stop engine safely
Just had the red triangle, low coolant, stop engine safely today … read more
Gunvir Singh
Gunvir Singh
1,949 satisfied customers
I think the water pump on my Volvo V40 is shot. How can I best diagnose the possibility &a
I think the water pump on my Volvo V40 is shot. How can I best diagnose the possibility & try to replace it myself; or what will be the cost for having it done professionally?… read more
Andy
Andy
Volvo Expert Technician
Vocational, Technical or Trade Scho
3,740 satisfied customers
i have a 2002 Volvo S80 where is the Radiator Cap. I have a
i have a 2002 Volvo S80 where is the Radiator Cap. I have a small leak and need to put solvent in radiator.… read more
Enes
Enes
VOLVO Master Technician
Vocational, Technical or Trade Scho
4,911 satisfied customers
Volvo XC90 2.5T: 2004 xc90 2.5t blowing large amount of white
2004 xc90 2.5t blowing large amount of white smoke, doesn't smell like coolant, losing oil… read more
Enes
Enes
VOLVO Master Technician
Vocational, Technical or Trade Scho
4,911 satisfied customers
Volvo XC90 2.5T: I own a 2006 XC90 with the 2.5T engine and
I own a 2006 XC90 with the 2.5T engine and with 115K kilometers on it. The Crankcase Ventilation Hose broke at the top, next to the engine oil filler cap because it was brittle. I took the XC90 to the… read more
Edward Clayton
Edward Clayton
Associate Degree
1,033 satisfied customers
I am getting the message coolant level low. Stop engine. Can
I am getting the message coolant level low. Stop engine. Can I add coolant myself? if so, what do I buy? Is it safe to drive w/out adding the coolant?… read more
Tim West
Tim West
Service Manager
Computer/ Automotive certifications
16 satisfied customers
my cooling fan makes a loud weird noise
my cooling fan makes a loud weird noise… read more
supermechanic
supermechanic
Service consultant
Vocational, Technical or Trade Scho
10 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x