Results 1 to 10 of 10

Thread: THOR MAF values (how to test)

  1. #1
    Join Date
    Oct 2010
    Location
    Carindale, Brisbane, Qld
    Posts
    652
    Total Downloaded
    0

    THOR MAF values (how to test)

    I tested my collection of MAFs today. I was surprised at the different values they returned.

    I have seen so many posts about engine power and hunting and idling problems. Often it is MAF related and it is an expensive item to replace with an OEM part which forces people to grab a cheaper alternative, which causes further problems. The issue with MAFS is that it is not a binary on/off works/broken situation. Rather it can work fine, not throw a code and return bad values which affects fuelling, performance and efficiency. This is especially true for LPG vehicles which can (if imperfectly tuned or setup) have the tendency to backfire through the intake and damage the MAF.

    I hereby pull together the values you are looking for to test a THOR MAF. Tests are done in neutral, engine hot all loads off. Most values are in kg/hr, but ODBII scanners (like Android's Tourque) measures in grams per second. I include both.

    At Idle...................... 20 kg/hr (5.5 g/s) ± 3 kg\hr (8.3 g/s) (^)
    At 2500 rpm............... 61 kg/hr (16/9 g/s) ± 3 kg\hr (8.3 g/s) (^)
    At 3000 rpm............... 90-100 kg/hr (25-27.8 g/s) (*)

    Bibliography:
    (^) - RAVE & MAF Values
    (*) - P38A P38 4.0 HSE MAF SENSOR DATA Is it working? Whats wrong? Please help. - Page 2 - Land Rover Zone
    Attached Images Attached Images
    Now: 2005 L322 Vogue 4.4 M62TU (Black)
    Before: 2000 P38A HSE 4.6 - stately capability | 2008 Kluger KX-S | 2004 Forester | 2000 Yamaha XJR1300 | 1993 VR Calais | 1974 HQ Statesman - 308 V8 | HT | HK

  2. #2
    Join Date
    May 2010
    Location
    Mindarie, Western Australia
    Posts
    1,141
    Total Downloaded
    0
    The car seems to be running fine, but this could mean time for another toy,an android device and an OBD 11 scanner to check the values. My car is like its owner and loves a drink . I don't like the look of the Mac versions.

    Just out of curiosity, I normally get around 13.5l/100k on the highway at up to 100kph but once I get over 110kph it increases dramatically up towards 16l/100k. Maybe a MAF sensor? Or is this a normal consumption value?
    Gary

  3. #3
    Join Date
    Aug 2007
    Location
    Brisbane
    Posts
    3,215
    Total Downloaded
    0
    Those consumption figures seem within the range. Also depends on the length of the trip, weight carried etc. Weight (bull bars/sump guards/winches) is a significant issue. It's one of the reasons car makers are ditching a full size spare in favour of a spraycan... in some vehicles, the weight of as full size spare can add 0.3L/100km. Aircon on a hot day is worth about 0.5-0.7L/100km. Once you get over 110kmh indeed over 80kmh, the drag coefficient rears its ugly head... double the speed, four times the drag... so the drag at 120kmh is X4 the drag at 60kmh...
    AT/MT tyres also chew more energy than H/T tyres and can marginally increase fuel consumption...

    Have you tried resetting the Adaptive Values for the EFI system? If you have a Faultmate/Nanocom it's an easy task. Sometimes it assists in reducing fuel consumption.
    MY99 RR P38 HSE 4.6 (Thor) gone (to Tasmania)
    2020 Subaru Impreza S ('SWMBO's Express' )
    2023 Ineos Grenadier Trialmaster (diesel)

  4. #4
    Join Date
    May 2010
    Location
    Mindarie, Western Australia
    Posts
    1,141
    Total Downloaded
    0
    Hoges, I've got the faultmate nano. It tells me what the problems are and allows me to clear them but does not allow you to adjust any values. It will be interesting to see what the MAF values are though.

  5. #5
    Join Date
    May 2008
    Location
    Canberra
    Posts
    1,834
    Total Downloaded
    0
    Quote Originally Posted by mtb_gary View Post
    Hoges, I've got the faultmate nano. It tells me what the problems are and allows me to clear them but does not allow you to adjust any values. It will be interesting to see what the MAF values are though.
    With the FultMate, you can reset the adaptive values through the "Other" menu under the respective Petrol EMS option (GEMS or Motronic). While you are using the FaultMate, give the transmission ECU a reset too (on post 99).
    My toys, projects and write-ups at PaulP38a.com

  6. #6
    Join Date
    Oct 2010
    Location
    Carindale, Brisbane, Qld
    Posts
    652
    Total Downloaded
    0
    The MAF numbers I pulled together in post 1 have a minor error. I hereby correct my maths. Since my numbers from that post have been copied and pasted a number of times to other threads, I will updates those threads with a link to this post.

    At Idle...................... 20 kg/hr (5.5 grams/sec) +/- 3 kg\hr (0.8 g/s) (^)
    At 2500 rpm............... 61 kg/hr (16.9 grams/sec) +/- 3 kg\hr (0.8 g/s) (^)
    At 3000 rpm............... 90-100 kg/hr (25-27.8 grams/sec) (*)

    Bibliography:
    (^) - RAVE & MAF Values
    (*) - P38A P38 4.0 HSE MAF SENSOR DATA Is it working? Whats wrong? Please help. - Page 2 - Land Rover Zone
    Now: 2005 L322 Vogue 4.4 M62TU (Black)
    Before: 2000 P38A HSE 4.6 - stately capability | 2008 Kluger KX-S | 2004 Forester | 2000 Yamaha XJR1300 | 1993 VR Calais | 1974 HQ Statesman - 308 V8 | HT | HK

  7. #7
    Join Date
    Feb 2013
    Location
    Gosford, NSW, Australia
    Posts
    2,556
    Total Downloaded
    0
    Mate

    Thanks for the corrections, I have only ever used the Kg/ht figures so I didn't hit any issues and those figures match the other posts i have read

    Steve

  8. #8
    Join Date
    Jun 2010
    Location
    Buderim
    Posts
    255
    Total Downloaded
    0
    Gary, your consumption figures are fine. Your MAF will be fine if the nano shows close to 20 at idle.
    Dont reset your your adaptions until you record them. Your fuel trims are your friends so look at them carefully. I assume you can record the data stream in video capture mode.
    Your BBS tool should report 3 fuel trims:Fuel Trim(short term fuel trim), Multi Trim and Idle Trim(long term trims)
    If when idling after warmup the Bank 1 and 2 idle trims and are .9 to 1.1, the MAF is about 20 and the oxy sensors are cycling at a regular frequency on both sides between 0.3 and .8 volts then all is good with your fuelling. The FuelTrim value should cycle at at similarly frequency to the oxy sensors around .98 to 1.02. The Multi Trims should be also in the range .9 to 1.1. The oxy sensor actual values are not so important as long as they cycle high/low at a regular frequency in closed loop(0.4 to 0.75 is Ok)Ideally all fuel trims should be very close to 1 - 0.98 to 1.02 is excellent.

    If an oxy sensor value is stuck high or low and the long term trims on Bank 1 or 2 are around .8 or 1.2 then you have a fuelling issue. This is an adaption command that is drifting towards setting a code.

    The Bosch system is very powerful yet simple. There are adaptions for idle and at load. The BBS tools are the best to latch onto the data streams correctly. Ive tried several cheap chinese jobs and the $10 bluetooth OBD transmitters with android apps and they report incorrect data for fuelling on these cars.

    So first, examine your data stream.If you have already reset, you need to go for a drive with highway/ city mix then look at your trims for any outliers.

    Hope this helps - but my fuel economy is the same as yours.

    BTW does everyone have intake air temps at least 10-15 degrees above ambient in cruise? Ive now rigged up a pipe to take air from the bumper/ headlight intersection and can reduce it to ambient plus 5 at cruise, although idling at the lights see it move quickly to 45 degrees. You need to remove a piece of the rubber seal at the bumper/headlight intersection - the total pressure is very high there at cruise.

  9. #9
    Join Date
    Aug 2012
    Location
    North Loburn, New Zealand
    Posts
    807
    Total Downloaded
    0
    I towed with my 02 4.6 for 14 hours last week, had 2 ton of boat and gear on the back and was up and down for half the trip, fairly steep. Returned 18L/100km, and was pleased with that and that the replacement transmission I put in held up - it was so comfortable too.

    I replaced the MAF with not OEM but one others use regularly...can't remember the name. I think I will get an OEM one and keep the other as a spare.

  10. #10
    Join Date
    Oct 2015
    Location
    Turkey
    Posts
    11
    Total Downloaded
    0
    Quote Originally Posted by glenhendry View Post
    I tested my collection of MAFs today. I was surprised at the different values they returned.

    I have seen so many posts about engine power and hunting and idling problems. Often it is MAF related and it is an expensive item to replace with an OEM part which forces people to grab a cheaper alternative, which causes further problems. The issue with MAFS is that it is not a binary on/off works/broken situation. Rather it can work fine, not throw a code and return bad values which affects fuelling, performance and efficiency. This is especially true for LPG vehicles which can (if imperfectly tuned or setup) have the tendency to backfire through the intake and damage the MAF.

    I hereby pull together the values you are looking for to test a THOR MAF. Tests are done in neutral, engine hot all loads off. Most values are in kg/hr, but ODBII scanners (like Android's Tourque) measures in grams per second. I include both.

    At Idle...................... 20 kg/hr (5.5 g/s) ± 3 kg\hr (8.3 g/s) (^)
    At 2500 rpm............... 61 kg/hr (16/9 g/s) ± 3 kg\hr (8.3 g/s) (^)
    At 3000 rpm............... 90-100 kg/hr (25-27.8 g/s) (*)

    Bibliography:
    (^) - RAVE & MAF Values
    (*) - P38A P38 4.0 HSE MAF SENSOR DATA Is it working? Whats wrong? Please help. - Page 2 - Land Rover Zone
    This definetely helped a lot.
    I have been tracking a over-fuel problem which causes gasoline to mix in to the oil.
    Now I see that my MAF reads %15-20 more than it should.
    I only got P1175 which is not even listed on RAVE
    All the injectors tested ok.
    Now I am replacing MAF with a BOSCH one.
    Hopefully this is it.

    Thank you again for the figures.

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!