Hi everyone, I am in search of a good used or source for rebuild service for my MAF. My car only runs with it disconnected. At idle it was reading 90+kg/h, dumping fuel.
Thanks,
Steve
Thanks,
Steve
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Thank you
MAF Sensor
- Thread starter Wagoneer300te
- Start date
I have a NOS in box Bosch MAF that I am willing to sell for 1500 euro because I have two good used MAF’s as spare for myself.
PM me if you are interested.
PM me if you are interested.
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Is this the part you have, because the part number you are who showing is for this .This is 0986 280 121. Thanks
View attachment 99694
View attachment 99694
That is the correct Bosch part number for the M119 MAF.
If there are enough demand, I will be able to design an electronic interface to convert the MAF used in Mercedes after 1996 for 500e. I will need to work with a 500e owner for fine tuning. All MAF share similar conversion curves but the offset and the gradient of the curve need to be matched. For my E320, 1994-5, I have optimized the interface design to use newer MAFs.
jftu105
jftu105
An MAF is made of a tube structure and a sensing unit (hot film sensor and electronic amplifier circuit). The sensing unit of another MAF can be removed and refit to the tube structure of the original. The MAF for E320, 1994-5 has a larger tube diameter (and longer) and the sensing unit is also a bit different in the fitment, not to mention different electronic connectors.
In my refitting of newer MAF to E320, 1994-5, if the MAF is for E320 1996-7, it is perfect fit in tube sizes except the connector and the conversion curve. My interface takes care of the conversion. I also sourced a few MAFs from C classes and a 500E (after 2000). They all have a shorter and smaller tube, but the sensing units are basically the same with slight differences in the conversion curve.
The interface circuit I designed has two pots for fine tuning. One adjusts the offset and one adjusts for the gain. Fine tuning can be done easily with Hfmscan. Without it, the O2 sensor signal should be used.
Typically, the newer sensing unit starts at 1V when the flowrate is zero, while the old MAF starts at about 0.4V with zero flowrate. The newer MAF sensing unit typically has a lower gain. I usually need to increase the gain by 10% to ensure proper measurement from idling to high speed cruising. After adjustment, Hfmscan confirms that the engine is running with lambda within +-5%, which is perfect.
Without proper adjustment, the engine could start and then die right off. If the adjustment is close but not fine tuned, the engine could run rich or lean.
Finally, the 500E of 1995 or older probably use the same sensing unit of E320, 1994-95. In that case, you only need to swap the sensing unit and reuse the original tube structure.
jftu105
In my refitting of newer MAF to E320, 1994-5, if the MAF is for E320 1996-7, it is perfect fit in tube sizes except the connector and the conversion curve. My interface takes care of the conversion. I also sourced a few MAFs from C classes and a 500E (after 2000). They all have a shorter and smaller tube, but the sensing units are basically the same with slight differences in the conversion curve.
The interface circuit I designed has two pots for fine tuning. One adjusts the offset and one adjusts for the gain. Fine tuning can be done easily with Hfmscan. Without it, the O2 sensor signal should be used.
Typically, the newer sensing unit starts at 1V when the flowrate is zero, while the old MAF starts at about 0.4V with zero flowrate. The newer MAF sensing unit typically has a lower gain. I usually need to increase the gain by 10% to ensure proper measurement from idling to high speed cruising. After adjustment, Hfmscan confirms that the engine is running with lambda within +-5%, which is perfect.
Without proper adjustment, the engine could start and then die right off. If the adjustment is close but not fine tuned, the engine could run rich or lean.
Finally, the 500E of 1995 or older probably use the same sensing unit of E320, 1994-95. In that case, you only need to swap the sensing unit and reuse the original tube structure.
jftu105
The M119 / E500E use a completely different MAF that is unique to the M119.97x engine series with LH-SFI; not used with *any* other Mercedes engine. It is aluminum bodied and has a hot wire element. AFAIK it is not the same dimensions as either the flow meters used in either HFM or ME injection.
Also, the top & bottom diameters are different. And, I don't know if the sensing portion can be easily removed and retrofitted from the later setup. I tried taking one apart but it appeared to be glued together, after removing the screws it didn't budge. I didn't use force to try and separate it so I'm not certain what is holding the sending assembly to the tube.
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Hot film or hot wire, the sensing concept is the same. The implementations could be different. Once it becomes the signal to the ECM, it is a dc signal, proportional to the flow rate. The connector appear to be the same as the older E320, 1994-1995. The pin connections typically are:
1: flowrate signal output
2: 12V, battery voltage
3: not connected
4: Chassis ground
5: Signal ground
The chassis ground and the signal ground are separated by 10 ohm (basically the same) to break up ground loops.
You can make a wire bundle to jump the connection so that you can measure the voltage to see if the pinouts are the same. Starts with engine not running to confirm the battery and ground connections. You should be getting 0.3-0.4 volt at the signal when the engine is not running.
1: flowrate signal output
2: 12V, battery voltage
3: not connected
4: Chassis ground
5: Signal ground
The chassis ground and the signal ground are separated by 10 ohm (basically the same) to break up ground loops.
You can make a wire bundle to jump the connection so that you can measure the voltage to see if the pinouts are the same. Starts with engine not running to confirm the battery and ground connections. You should be getting 0.3-0.4 volt at the signal when the engine is not running.
By the way, the sensing unit is sealed to the tube structure with an o-ring. It could be tight. If you are going to take it apart, do it with a bad one. After loosening the screws, you need to wiggle hard and it would come apart. It could be quite tight.
The newer MAF put the air temperature sensor in the MAF sensing unit.
jftu105
The newer MAF put the air temperature sensor in the MAF sensing unit.
jftu105
On the M119 MAF, all five wires are used; four are signals to the LH module, the fifth is chassis ground. See attached photo with the schematic / wiring diagram.
LH pin 17 = Air mass signal
LH pin 23 = Air mass sensor voltage supply
LH pin 34 = Air mass sensor ground
LH pin 37 = Cleaning signal for air mass sensor
LH module pinouts: http://www.w124performance.com/docs/mb/M119/M119_LH_pinouts.pdf
LH pin 17 = Air mass signal
LH pin 23 = Air mass sensor voltage supply
LH pin 34 = Air mass sensor ground
LH pin 37 = Cleaning signal for air mass sensor
LH module pinouts: http://www.w124performance.com/docs/mb/M119/M119_LH_pinouts.pdf
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So, this MAF for 500e is based on the hot wire. Compared with hot film, a hot wire sensor needs a burn-off cycle to keep the wire clean for accurate measurements. The hot wire-based sensor is more fragile and this is the reason newer MAFs are based on hot film. Therefore, one wire is used to send high current for burning purposes.
The other four wires are similar. Therefore, it is clear to me that the MAF for 500e can be upgraded to newer MAF with hot film. The burn-off wire can be left without connected. It does not hurt anything. The rest four signals are similar to those of E320, 1994-5. The battery supply voltage, the signal output, the Chassis ground and the signal ground.
I think that this is worth doing if the MAF costs 1500 euro.
jftu105
The other four wires are similar. Therefore, it is clear to me that the MAF for 500e can be upgraded to newer MAF with hot film. The burn-off wire can be left without connected. It does not hurt anything. The rest four signals are similar to those of E320, 1994-5. The battery supply voltage, the signal output, the Chassis ground and the signal ground.
I think that this is worth doing if the MAF costs 1500 euro.
jftu105
The burn-off signal wire, if disconnected, would trigger a fault code and also turn on the CEL. Easy enough to pull the CEL bulb, but some folks may not want to do that (or, may cause issues for emissions testing).
The M119 MAF is NLA, so eventually there might be a need for a conversion, if Bosch (or anyone else) doesn't start rebuilding them again. At the moment the main issue is if the HFM sensor assembly can be physically adapted to the M119 aluminum housing/tube.
M104 photos below... the tube design isn't even remotely similar to M119. The W124 M104 MAF appears to be similar (physically) to the W210/etc M104 and M112. Note there are 2 screws where the sensor part is easily removed from the housing. The LH MAF's are NOTHING like this.
M119 MAF sensor block is a large trapezoidal affair. Photo below showing the inside is from a failed unit that melted the plastic.
That entire section would have to be removed and replaced with an alternative item, and since it matches the curve of the aluminum housing, I don't think it would be trivial. Probably would be easier to use the late-style unit complete, but then there are dimensional issues...
That entire section would have to be removed and replaced with an alternative item, and since it matches the curve of the aluminum housing, I don't think it would be trivial. Probably would be easier to use the late-style unit complete, but then there are dimensional issues...
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The burn-off wire can be connected to a power resistor to burn it for nothing so that it won't trigger the engine check light. If you send me a bad MAF, I can study how to do the conversion. Mechanically, some fittings can be made to fit a different sensing unit and the original tube can be reused. An MAF is a fairly simple device. Back in 60s and 70s, it is a space-age technology and some Ph.D. theses were on its modeling or use for turbulence measurement. Today, it is a commodity.
jftu105
jftu105
I have a MAF sensor for a Ferrari 465GT that seems to share the same values as the failed MAF on my E420 it was 80 dollars from AP electronics . The difference is the plug which is rectangular not round, is it worth trying a conversion ?
I am surprised that an MAF for Ferrari only costs $80. The conversion requires the information about pinouts. In my current design of the conversion interface, there are several voltage regulators to provide a +5V to the new MAF used in later year MB, to provide a bias adjustment for conversion, and to provide a -5V for the op-amp. There could be a built-in temperature sensors too, which can be passed through directly. The conversion interface can adjust nearly all conversion curves but the key is have a feedback for fine tuning. I have Hfmscan for this purpose.
For E420, it would be much easier to acquire a used MB MAF for the purpose of conversion.
jftu105
For E420, it would be much easier to acquire a used MB MAF for the purpose of conversion.
jftu105
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I bought 2 and i did use one on the 465.and I will attempt to use the other on my E420
I had my BMW E34 M5's MAF rebuilt by Injection labs in Colorado. I called them and they told me they could also rebuild the MAF on my '93 500SL.
May be worth a try?
May be worth a try?
I downloaded Hfmscan and I'm waiting for some interface cables to make everything work, Do we know what a baseline for the E500 should be or am I looking for a reference voltage?Do you have access to a scanner that will show live data from the LH module, so you can see the airflow readings in kg/hr? That would prove if your modified Ferrari MAF is providing incorrect readings.
Did you get any bad mafs to experiment with? Was your interface able to work with 500e?
There are rebuilt MAFs for sale in Aliexpress. I ordered one for M120 engine to test. Never received, money back from Mastercard however. Now I have a bad MAF in 119. 500 SE-92. I wonder if the demand of the Mafs is so poor, that there is no rebuild service in Europe. Or perhaps the needed testing equipment is too expensive.
If the car drives normally with MAF unplugged, but runs poorly with MAF connected, it's pretty likely the MAF is defective. Viewing the live data will confirm it 100% though.
I assume your upper engine wiring harness has been replaced, and is not original from the early 90's?
I assume your upper engine wiring harness has been replaced, and is not original from the early 90's?
The general tendency is to use-trash-buy new, so I'm afraid that we may see less and less rebuild facilities in the future. But in the pile of bookmarks with service workshops I have one which claims to repair and rebuild majority of the electronic automotive stuff, including air flow meters: BBA Reman . Not sure they will be able to fix yours, but a question does not cost anything
. Surprisingly, they have an office in Poland, so if you need I may give them a call and ask for more details.
Bookmarked, thank you!
I own 95 SL500, bought for parts while back. Prior owner spent thousands with different shops trying to "fix" the car, was not running well at all. Id did have new wiring harness, and rebuilt MAF (Bosch), looked brand new. The same MAF as in the picture on post #4... I spent quite a bit of time tracing the issues, replacing the vacuum lines, testing all ignition components (which most of then were also replaced by prior owner) to the best that I could... At the end the faulty part was that very shiny Bosch rebuilt MAF. Ended up using a used junk yard find, and that was that, it's been couple of years now, still good!I rebuilt the wiring harness for a while ago. The original was a mess!
I was positively surprised, the shorts did not burn LH-computer or the car did not catch a fire!
Same problem with my SL600 and all early 90:s Mercs as well known.
The Soya based wiring insulation
I indeed kept that Bosch unit, just as a core for possible future rebuild... Someone posted a year ago that Autozone supposedly accepted these Bosch MAF units and send them out for rebuild, but could never find the follow up to that old thread.
Thanks for heads up, saved that link to BBA too, UK company I see...The general tendency is to use-trash-buy new, so I'm afraid that we may see less and less rebuild facilities in the future. But in the pile of bookmarks with service workshops I have one which claims to repair and rebuild majority of the electronic automotive stuff, including air flow meters: BBA Reman . Not sure they will be able to fix yours, but a question does not cost anything
Regards,
D
Not MB, but Porsche 928 MAF but I find this page to be rather informative for the hot MAF details, behavior, testing, etc: MAF repair And the actual element looks nearly identical to M119/LH combo (also uses LH in these 928 cars, as well as the 722.3 transmissions...)
I wonder if this place would also be an option to rebuild our Bosch units?
Regards,
D
I wonder if this place would also be an option to rebuild our Bosch units?
Regards,
D
Cardone will repair your MAF following the instructions below....
Customer Service Question from Cardone.com
Customer Service Question from Cardone.com
"Good Morning Lee, thank you for your request. I do apologize but we are currently out of stock with no E.T.A. as to when we will receive part # 74-10111. This part is however eligible for our rebuild and return program. To participate in the program you can take your core into any parts distributor that works with us, such as; Advance Auto Parts, Oreillys, Napa, Carquest, Pep Boys, and many others. The location will send your core to us, and once we receive your item there is a 3-5 business day turnaround time to complete a rebuild with an 80% chance of a rebuild. If you have any questions, feel free to contact us at 1-800-777-4780."
That website is so awesome in all its 1998-eta glory!! Btw this warning about K&Ns here and the hot-wire MAF issues (as opposed to Hot Film)
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It`s good to know, that there is at least Cardone in U.S for rebuild services. I was asking BBA, but obviously the do nothing. Not even answer for customers inquiry.
I found a cheap, untested MAF in Ebay, no warranty. That`s a lottery where I usually I have bad luck. Not arrived yet.
I found a cheap, untested MAF in Ebay, no warranty. That`s a lottery where I usually I have bad luck. Not arrived yet.
I'm curious if the M119.97x reacts the same way. The M119 LH-SFI system monitors the O2 sensor readings and adjusts adaptation. The Porch LH system is an older batch-injection design, not SFI (sequential, firing each injector separately). Which is also why the SharkTuner will not work for M119.97x.
Cheers Lee!
Thanks for the research, great info in case of rebuild is needed!
Regards,
D
Cardone was unable to rebuild my m119 MAF sensor and sent it back. No information either about what was wrong with the unit. I called to check status and was told their repair and rebuild service was closed over the holidays, during the time it was received and returned. Hopefully this is not true and the unit was actually evaluated. In the end it cost me shipping and some time. I cannot confirm that Cardone can actually rebuild these units.Cheers Lee!
Thanks for the research, great info in case of rebuild is needed!
Regards,
D
Basically, there is no way to rebuild an MAF. An MAF contains a sensing element (hot film or hot wire), an miniaturized electronic amplifier circuit, protected in silicon, and the housing/connector. There is essentially no way to fix the amplifier circuit and the sensing element is not an off shelf standard component. You simply cannot remove or replace any of those tiny electronic components and chips in the tiny amplifier circuit. The MAF cleaning spray, $7-10 a bottle, typically does not do a thing because the sensing element of MAF stays clean mostly with the clean air passing through it.
Each MAF needs to be calibrated after it is assembled. The good news is that the MAF typically is long lasting until it eventually dies due to aging and overheating. I had to replace every MAF of my [6-cylinder] W124's because MB designers decided to place it right over the exhaust manifolds. Now, I have heat shields over every MAF of my W124. The conversion box I designed (see other thread of mine on MAF conversion) is used to convert a newer MAF element and put it in a housing for W124. The newer MAF is more robust compared with the original ones used in W124, but electronically they are not compatible with W124. The conversion box, theoretically, can convert any MAF after a proper calibration process.
The conclusion: rebuilding an MAF is simply not feasible unless they replace the sensing/amplifier unit entirely. You can do that yourself by loosening two screws if you can find a correct sensing/amplifier unit.
jftu105
Each MAF needs to be calibrated after it is assembled. The good news is that the MAF typically is long lasting until it eventually dies due to aging and overheating. I had to replace every MAF of my [6-cylinder] W124's because MB designers decided to place it right over the exhaust manifolds. Now, I have heat shields over every MAF of my W124. The conversion box I designed (see other thread of mine on MAF conversion) is used to convert a newer MAF element and put it in a housing for W124. The newer MAF is more robust compared with the original ones used in W124, but electronically they are not compatible with W124. The conversion box, theoretically, can convert any MAF after a proper calibration process.
The conclusion: rebuilding an MAF is simply not feasible unless they replace the sensing/amplifier unit entirely. You can do that yourself by loosening two screws if you can find a correct sensing/amplifier unit.
jftu105
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