Mass Air Flow Sensor

Discussion in 'Discovery' started by kmatt, Jan 29, 2010.

  1. kmatt

    kmatt Member

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    Hello,

    I have a 2001 Discovery II and I need to replace my Mass Air Flow sensor due to failing inspection for OBD codes P0171, and P0174. Can anyone tell me how much I should expect to pay for the part and if I take it to the dealer for replacement, what the cost should run.

    Thanks.
     
  2. joey

    joey Custom Rover Accessories Staff Member

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  3. kmatt

    kmatt Member

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    Thanks, Joey, I really appreciate the info. I have never been under the hood of a vehicle other than checking the oil level and adding windshield washer fluid. So, I am a little nervous when it comes to replacing things.

    kmatt
     
  4. beemer

    beemer Full Access Member

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    Will the MASS meters clean up if you used a MASS meter cleaner then flushed it real good let dry a couple days in a warm place? Just thinking here for the spare 95 MASS unit I have.
    I changed the 1.86 volt output to 1.80 per RPI specs for their Tornado chip I run and I installed. This spare MASS meter ran great for 5 miles then became sloppy rich idle with fault code 12 a MASS meter code. I was thinking about flushing it before taking it apart as the gasket would be destroyed just to get at the hot wire and the second wire.
     
  5. joey

    joey Custom Rover Accessories Staff Member

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    You can clean with cleaner (drying time is about 10 minutes max) if you use MAF cleaner as it is a non-residue cleaner.

    Normally what happens from what I have read is it wears out the small part of the wire, I read somewhere that someone with more knowledge then me, opened it up and adjusted the wire and sensor to be like new.
     
  6. Disco Mike

    Disco Mike Full Access Member

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    Before you throw a MAF at it, how is the engine starting lately, does your exhaust smell different and has the tranny been feeling funning when shifting into 3rd. or 4th. gears?
    There are a few other things that can cause the 171 and 174 and not be a MAF, like a leak in the air filter box, MAF o-ring and other vacuum leaks.
    If it is needed, buy only a new, in a Rover box, Bosch MAF, don't buy a generic Bosh MAF or after market replacement will often not run without throwing new codes.
    In the future, inspect and replace your air filter more frequently to prevent MAF failures.
     
  7. beemer

    beemer Full Access Member

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    This is good to know thanks Joey. I'll spray it first, if still a problem i'll pull the end cover off to see the wires directly and clean them plus make a new gasket. Worth a try as I want to keep the original unit untouched for future smog tests besides this is the only unit i have that works.
    I sent a email off to Mark who designed the Tornado chip that RPI sells with questions. I was thinking about locating a 4.6 MASS meter also to reduce the restriction as the intake, heads and exhaust are free flowing vs adding a 4.6 MASS on a stock missaligned port mess of an engine is fruitless and a waste. I want the ability to play with more power plus can switch back and pass the smog tests without a problem. I runs too clean when set up for smog, mad at myself I should of installed a bigger cam. With this intake extension the gas gauge seems to be stuck or dropping slower as there is an increase in MPG and this with playing not pinching every drop. The flapper that BMW used on their MASS meters it was a wiper under the top cover that was easy to readjust, just the carbon track needed cleaning or could wear out. A simple system to readjust that works great. The 3.5 liter unit on a 2.5 liter motor then let the performance chip relearn the system made a big difference in performance plus the switch to newer style 4 hole injectors vs single pentile units. Again another brand of vehicle and easy to convert for smog testing then back again.
     
    Last edited: Feb 1, 2010
  8. Disco Mike

    Disco Mike Full Access Member

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    I don't want to step on other toes, but it is rare, no mater what cleaner or techniques is used, that a new Bosch MAF will take a cleaning without killing it.
    As for you ideas around 2 different set ups, don't waste your time trying. Our 50 year old engine can't put out much more power and with the current ECU's, they won't let you try and second guess them.
    If you want to do anything, since you sure don't need any more horse power off road, work on improving what you have.
     
  9. beemer

    beemer Full Access Member

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    Not to start a pissing war but hear goes;
    Sorry Mike I can't believe your above statements as I have hands on. I have more power and torque way more than even the 4.6 had when first installed. Your don't need more HP (?) lower your meds please as these Rovers are already under powered look at the power to weight ratio number, kind of sick my friend.
    First off at 72K the guttless 3.9 became a 4.6 for 500 plus miles of working it breaking it in. Ran better than the 3.9 yes. Next the RPI Tornado chip, this woke it up big time. Then recurved the dizzy and added a vacuum advance unit from Oz., way better than the POS from Rover. Then the intake, heads, exhaust manifolds port matched plus MagnaFlow high flow cats with Borla cat back. Another increase of performance. Then the ram cold air you can feel the difference with this as this is a 1 minute swap back and retest. Then the restriction to the hot coolant to the plenum, stupid HP sucking and detonaiton causing problem. I just finished the injector swap to more modern 4 hole Bosch disc units plus the 1 1/2" ram tube extension lift plus the .250" plenum spacer I machined. This last injector with intake extensions project made a difference as much as going from the 3.9 to a 4.6 engine another increase in the fun and run factor. This thing is fun hands down to drive, way better than the stock 4.6. I may stop by and see Mike Green In Livermore Calif. 28 miles from me and let him test drive this D1 again. he drove it with after the 4.6 install. Oh he's Rover trained plus off roads and races. Dump the clutch in 2nd if rolling from a stop in front of a cop then add throttle with normal take offs. This became a way better low end pulling motor, I bet better for off road where low end torque is needed but still hits 5,800 if I want to beat some jackazz in a LR3 which is easy to do plus fun as hell plus I can out corner them. Set up for the street action only. Yes there is a lot you can do to increase performance plus still pass smog tests, it seems 30 years in service hasn't opened your mind to beyond what you have been trained by Rover, kind of sad. Sorry to be blunt I speak with facts. With all respect Mike i'm not belittling you, this is what I have done besides many other secrets to this 4.6 engine with results. My fear is blowing those two spider weak diffs and the 5 speed.
    Today I did a 5th gear idle down clean until only compression alone stalled the motor plus I can pull away in 3rd or 4th at 850 rpms or maintain speed in 5th at 30 mph. A very flexible motor now. I swap back to the original MASS 3.9 vs the spare altered voltage 3.9 and the 4.6 unit, reset the TPS then pass smog with ease. Home again to retune for power and fun again within 20 minutes. This I have built would make for one hell of a good low rpm torque motor for off road plus a sleeper on the street that has surprised many of vehicles out of my league. Gas mileage also increased, a win win 8 year project, With your 30 years as a service manager you should tell RPI and Rimmer Brothers that they are making too much magical HP. A 15 year D1 owner 40 years with the 215 motor. NUFF SAID.
     
    Last edited: Feb 2, 2010
  10. Disco Mike

    Disco Mike Full Access Member

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    So what does your long reply have to do with cleaning a new style Bosch MAF .
    Yes, I hear you built a 3.9 and got more power, that's good but this has nothing to do with this thread.
     

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