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Mass air flow sensor failure
#1

For the last couple of weeks I have been dealing with some drivability issues. The car kept surging when I was off or partially off the gas pedal. Initially I thought it was a vacuum leak. However a vacuum check confirmed there to be no leaks, but the problem persisted and got worse and the fuel consumption nosedived.



Error codes indicated that the car was running to rich. My PM has determined that the MAF sensor has failed. Cleaning it had no impact on the problem. He disconnected the MAF and the cars runs significantly better than before. It appears as if there are no MAF sensors to be had in the US at the moment and only a handful in Germany according to Porsche and a new one from Germany will cost north of $700.00. My PM will take a harder look at procuring one next week, but I am wondering about the wisdom of using one from a salvaged car, assuming there are any to be found in a salvage yard. Your thoughts are appreciated.
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#2

I have good ones-used but tested
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#3

The unit is pretty much the same as a bunch of common Bosch equipped Saabs, Volvos, Audis, etc except for the egg crate flow straighteners in place of the typical screen. I have run with a Volvo MAF with no ill effects. The Audi RS2 (Porsche tuned) uses the same MAF also but these are also hard to find.



There is data out there showing the RS2 MAF has the same output curve as the Audi 200 MAF but a little less flow due to the screen on the latter.



http://www.s2central.net/ds_G70.html



If you are in a hurry to get back on the road try an Audi 200, Volvo 960 V6 MAF or the similar unit from the old Saab 9000 and run it while you get your 968 MAF rebuilt by Injection Labs here in beautiful Boulder Colorado. Or swap the sensors between the common housing and the uncommon 968 / RS2 housing and go drive.



Cheers,

-Joel.
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#4

Douglas Valley breakers in the UK are worth trying for smaller items to ship to the USA.
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#5

I have had good luck using CRC MAF sensor cleaner for the hot wire MAF sensors like the type on our cars. The way these sensor work is a computerized control of temperature of the "HOT" wire hanging in the middle of the air flow through the intake tube. As air passes by the wire, the air cools the wire and the computer responds by adding amperage to the wire to keep the wire at a calibrated temperature, this in turn is translated into a data input of "The Mass of Air" coming into the engine, along with throttle angle opening, engine rpm, coolant temperature, air temperature, etc. the computer pulses the injectors to provide an optimum fuel/air ratio- Stociometric 14.6 to 1 (if memory serves me correctly). When dirt, smut, etc gets on the wire, along with the heat of the wire, the wire becomes insulated (puts a parka on the wire) and the wire can no longer accurately sense the incoming air flow. If you add a K&N type (oil impregnated fabric) filter to the mix, you are just speeding up the "shellacing" of the MAF sensor. Now that K&N doesn't seem so great. DO NOT USE CARBURETOR SPRAY ON THE MAF SENSOR. The carb spray cleans the sensor really well, but the delivery tempurature of the carb spray makes a meat locker feel like the Bahamas, inturn de-calibrating that calibrated hot wire sensor. This $8 per can spray can make that 3.0L purr. I would at least try this prior to $ up for a new MAF. My 2 cents worth, if I share it 50 times it's a buck. If you mad it to this point you deserved the nap caused by this post. Cheers
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#6

I've used the CRC MAF cleaner as preventative maintenance on all my cars. Can't say I've ever noticed any difference in the way any of them ran afterward, but I figure it's a good habit to get into. I hope it helps the OP's problem.
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#7

I concur on the MAF cleaning.



Also here is a thread where alternative MAFs are discussed for the Audi ur S4/S6/200 and some part number clues for replacements:



http://forums.quattroworld.com/s4s6/threads/2560.phtml
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#8

This place will also rebuild it for you, there in CO. http://www.injectionlabs.com/home.html
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Current:
2016 Cayman S
Former:
94 968 Cab 6 Spd. Black/Cashmere D1R SC
86.5 928 Garnet Red Metallic
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#9

I love the preventive concept, live by it and wish all followed suit. Many do not and end up getting a cleaning to restore performance. +1 for everyone in the preventive frame of mind.
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#10

I've got a number of pieces of the egg crate straightener at the MAF inlet that are broken off. Is there anyway to just replace this part? Does it even make any difference?
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#11

The <acronym title='mass air flow'>MAF</acronym> was cleaned, actually wasn't all that dirty. The problem is that there is no signal from the <acronym title='mass air flow'>MAF</acronym> to engine management computer whci suggests that it has failed in some manner.
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#12

Replacement <acronym title='mass air flow'>MAF</acronym> installed today and the call really runs much better. The replacement was a used one from RS Barn. I've been driving the car without a functioning <acronym title='mass air flow'>MAF</acronym> for about a week and a half. What a pig, it consumed a vast amount of fuel, no grunt off the line and a huge flat spot in the power curve. But it is back in good form.
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#13

Anybody know if a MAF from a F-355 Ferrari can be used on a 968?  Rolleyes

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#14

The same one mentioned above for the Volvo V6 is the same as a 355 the only difference is the mesh grill instead of the egg crate in the 968 one.


You are quite safe using the cheap one off eBay for $50
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#15

I didn't buy the cheap one.  B)

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#16

We had the cheap one on a dyno today and ran them both one after the other


The cheap one had a better curve than the original figure that one out


50 dollars better that close to 1000 dollars and it does not have a Porsche or Bosch label on it
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#17

I'm confused ( sadly that happens with greater frequency nowadays ) - so this inexpensive and readily available MAF which fits and works perfectly in our cars is for which year(s) and models Volvos ?

The difference in the mesh grill vs egg crate probably makes little or no difference in a stock or a chipped / air box modded car , but I have doubts it'll run as well in the supercharged 968s given the extensive, highly customized tuning where maybe the slightest difference in air flow could have a material impact on function ? Not sure and maybe it would be perfectly fine but for now just wondering about which specific Volvo MAF we're talking about ?.
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#18

It's for the 2.9l V6 940 also the Ferrari 355


Bosch part number 0280213012

http://www.amazon.com/Sensor-Meter-Volvo...B00RPI4H1S


$79!
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#19

<sub>I like Wildcat's solution. Can I install the $2,000 Ferrari MAF to replace the $1,000 Porsche part. Hidden bling
Smile</sub>

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#20

This gives me hope - not necessarily because of the price difference ( that's just a great bonus ) but because there are some replacement parts out there as alternatives to various essential 968 parts which at one point or another will become NLA.
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