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found a great article explaining why so many MTX-L units fail
How to id the sensor
Even with a LSU 4.2, the controller makes a big difference. Bosch sensors are not easy to fail even with a LSU 4.2, if controlled appropriately. Especially, LSU 4.9 is designed for more than 10 year life because it has to, for the vehicle life. It should not fail in short time, like a couple of years. Many OEM cars have been running with LSU 4.9 for years. Why so many aftermarket wideband systems have failed LSU sensors? Because many of them don't have a good heating control strategy. The number 1 failure mode of a LSU sensor is being heated up too fast or too earlier
The major difference between LSU 4.9 and 4.2 is that LSU 4.9 uses the reference pumping-current, while LSU 4.2 uses the reference air. What does this mean? Let's read this true story from the auto industries: when Bosch first designed a wideband oxygen sensor, a reference air cell was used to provide a reference of stoic AFR. The technology was to keep the pumping cell balanced with the reference air cell, by pumping the oxygen out of the pumping cell. The pumping current was the indication of the actual AFR in the exhaust gas. The bigger the pumping current, the more the oxygen in the exhaust, and vice versa. Therefore the reference air was vital to the accuracy of the sensor, because it was THE reference. It worked well in the lab, but not so good in the real life, because the environment around the sensor on a car was much worse. The reference air cell was susceptible to be contaminated by the exhaust gas, and / or other surrounding pollutions. Once the reference air was contaminated, the whole characteristics of the sensor were shifted to the low side. It was called "Characteristic Shifted Down", or CSD, in the industries. This was the biggest problem of LSU 4.2 that was used in some early OEM applications. And it caused the big quality issue to Bosch. To fix this problem, Bosch redesigned the LSU sensor, and came up with LSU 4.9 version. LSU 4.9 sensor completely got rid of the reference air. Instead, it used a reference pumping current which was equivalent to the stoic reference air, but without having any physical air in the cell. So the technology became: the actual pumping current was compared to the reference pumping current to maintain the balance. The actual pumping current was still the indication of the actaul AFR, but the reference was a calibrated electrical signal, and stayed same all the time, all the situations.
This is the fundamental difference between the LSU 4.2 and LSU 4.9.
LSU 4.9 gets rid of the reference air, and therefore gets rid of the biggest failure mode. As a result, LSU 4.9 has a long life and can maintain the accuracy throughout the life. Only since then, Bosch LSU sensors have been used widely in the auto industries.
Nowadays, all OEMs who use Bosch O2 sensors are using LSU 4.9. GM, Ford, and Chrysler all use LSU 4.9 now. If you check out the O2 sensors on your recently bought vehicles, cars/SUVs/Pickups, (since 2007 or later), on the exhaust manifolds, you will find out that they are all exclusively LSU 4.9. No more 4.2 sensors can you find on OEM vehicles.
Most aftermarket wideband controllers are still using LSU 4.2, mainly for low cost reasons. Bosch sells the LSU 4.2 to the aftermarket at a much lower price than LSU 4.9. Plus, many of those companies do not want to or are not able to adapt the new LSU 4.9 sensors. There is a big mis-understanding that LSU 4.9 is only for diesel engines, because it can measure very lean AFRs. That's not true. There is a diesel version of LSU 4.9, called LSU4.9D, mainly because of fuel and temperature difference. LSU 4.9 has been widely used with the gasoline engines. In fact, it is the most popular gasoline engine O2 sensor now, not only because it measures wide range of AFR, but also because it has the very good reliability, and high accuracy.
There are a few wideband controller companies in the aftermarket using LSU 4.9. But that does not mean all controllers using LSU 4.9 are equal. Even with the same LSU 4.9 sensor, the controller can make a big difference. Some wideband controllers are designed for AFR display only, and they are named as "wideband AFR gauges" instead of controllers. You can imagine that those wideband gauges do not have good accuracy and fast response rate because they are not designed for those purposes. Those gauges are more for good looking than for engine tuning purposes. For engine controls, the accuracy and response rate are the most critical characteristics of a wideband controller. One way to tell whether a wideband controller is good or not, is to see whether it can be used as a feedback device for the ECU. A feedback device must provide a real-time signal in the fast rate and high accuracy, even under dynamic situations. The requirements for a feedback device are much, much more than those for a gauge.
Even with a LSU 4.2, the controller makes a big difference. Bosch sensors are not easy to fail even with a LSU 4.2, if controlled appropriately. Especially, LSU 4.9 is designed for more than 10 year life because it has to, for the vehicle life. It should not fail in short time, like a couple of years. Many OEM cars have been running with LSU 4.9 for years. Why so many aftermarket wideband systems have failed LSU sensors? Because many of them don't have a good heating control strategy. The number 1 failure mode of a LSU sensor is being heated up too fast or too earlier. O2 sensors are made of ceramic materials, which can be damaged by severe thermal shocks, like condensations, liquid residuals, or just high heating power when it's still cold. A very careful heating strategy to detect the dew point and a close-loop sensor temperature control are vital for the life of the sensors. That's why the LSU sensor must be controlled in the context of engine controls. You may say, only those know engine controls can design a good wideband controller.
my first MTX-l sensor failed after less than 2 years of daily driving on a dyno tuned all motor b series, in proper location with proper wiring by the manual.
second one failed on the 3rd start of a fresh turbo build before I even set up crome to tune it lol
car didn't even warm up...
the ebay MTX-L kits almost all come with LSU 4.2 beware buyers that's why they are so cheap compared to everywhere else. most likely overstock.
and trying to get innovate to own up and at least admit that its partially sensor fault and partially controller fault is near impossible. because if they admit it they would have to replace a lot of sensors. and probably go bankrupt...
they could offer to replace the 4.2 sensors at discounted price but I think that's too much to ask lol.
I'm personally pretty disappointed with the MTX-L kit. but seems like other innovate widebands are more reliable
now I have another brand new kit with 4.2 sensor and its almost certain death within short time so I don't even want to open it and waste my money since I know its gonna go out shortly after
had to spend another 80 bucks in addition to the price of the kit to order LSU 4.9 and hope that it lasts longer than 2 years
OP, How far mounted is the O2 wb sensor is from the turbo? Was it covered with black soot?
I have found that most blown sensors are due to placement position. (too far) They should be placed 5-8'' from exhaust turbine to keep them cleaned. Now if you have a high powered engine having to run sustained WOT then you move it down.
Also, I see many guys having the power turned on the WB sensor before a start.
Like when someone trying to ''tune'' cold start. Cold start are tough on a pre heated sensor by thermo shock loading it with unburned fuel from the first engine revolutions. E85 apply here.
It was in downpipe.
Wherever the bung was
Of course its gonna be covered in black soot first start.
How am i supposed to tune if i cant use the sensor on untuned motor lol
From that article it seems like 4.2 lsu is poorly designed and it goes out alot otherwise there would be no reason for making 4.9lsu
It was in downpipe.
Wherever the bung was
Of course its gonna be covered in black soot first start.
How am i supposed to tune if i cant use the sensor on untuned motor lol
From that article it seems like 4.2 lsu is poorly designed and it goes out a lot otherwise there would be no reason for making 4.9lsu
Wow, I asked you a simple question and your best answer was wherever the bung was. lol
Anyways, yes the lsu4.9 is better.
Man, reading this thread I'm glad I didn't go with the Innovate setup after all. ~90k on my PLX/4.2 at the moment and it's still going. I recently swapped it out with a known good one for a couple of days as a sanity check, no changes so I put it back in. It has survived my attempts at lean burn, many engine off warmups to log cold starts, etc, in the time I've had it.
4.2s weren't really a bad design, just based on technology of the day. There are millions of them out there living out their lives in production cars. Many have failed, many haven't.
The 4.9 is way better for sure though. Fast, reliable, and predictable. Fast enough to pick out individual misfires at 11.5k-12k (YMMV depending on logging capability). The ultra-expensive NTKs at work are slowly being replaced with 4.9s as we figure out how to keep them alive with our particular controllers (not the sensors' fault). They survive multiple engines with extended periods of high EGT and some occasionally nasty combustion events.
manual says its compatible with both if I remember correctly
at least for MTX-L I don't think others are compatible with both
I went to pick some at puck and pull but motherfrs cut every single one.
******** take the headers off and cut the widebands off with them...
I could have got some for cheap for now but they re either bent or wires cut... theres a lot of lsu 4.2 sensors there
Double check that. You may be able to do a firmware update with the Innovate, I have no idea. You will at least have to repin as the two have different connector shells and different pin arrangements within those shells (Pins are 180* WRT the clip, shell is similar shape but not compatible). The first pic I found via Google, from AEM:
well damng I learnd another something new today...
I couldn't figure out what this thing was and if I had to transfer it with the plug I guess I would have to since it contains the calibration. (I'm not sure if 4.9lsu has the calibration resistor as well or not.
but according to that guy innovative defecated on that calibration resistor and did their own thing...
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The sensor itself is what receives the calibration, by the factory, at the time of manufacture. If you look closely at the first picture in post 23, you'll note a sort of rectangular lump protruding back from the connector on the sensor side. This is what's inside that lump:
Like all other wideband sensors which are specified for an OEM application, that lump contains a calibration resistor. At the time of manufacture, Bosch / NGK / whomever expose the sensor to a reference gas, and then laser-etch the calibration resistor (which is printed on a circuit board) to a value which corresponds to the observed offset of the sensor. This calibration is read by the ECU (or wideband controller) on its own wire. In the diagram below, it is the green wire labeled RCAL:
Thus, all AEM and 14point7 need to do is emulate the behavior of an OEM ECU in this regard. Read the calibration resistor, and adjust your internal software offset accordingly. If you swap the wideband sensor in an OEM application, you don't need to re-calibrate anything- the ECU just reads the new calibration resistor value. Same thing here.
Innovate has got us all convinced that controllers "need" to be uniquely calibrated to specific sensors. Well, they sort of have a point, at least in their design. Innovate recognizes that electronic devices change in performance as they age, especially when they're bathed in a stream of hot exhaust gas all the time. In their literature, they cite this Bosch technical document which gives a tolerance spec for that particular sensor of ± .15 AFR at 11.76:1 (± 0.01 at 0.8λ), degrading all the way to ± .59 AFR at 11.76:1 (± 0.04 at 0.8λ) after 2,000 hours, and cite even worse numbers on the lean side. So, they've decided that to differentiate themselves in the market, they will completely ignore the factory calibration resistor and instead allow the user to uniquely calibrate the sensor as it ages. As a result, you must calibrate new sensors with the Innovate controllers, as they lack the ability to read the factory calibration resistor on the sensor.
TL;DR:
With the 14point7 and AEM systems, the controller itself is not factory calibrated at all. It reads and automatically adjusts to the calibration value of whatever sensor is plugged into it. Thus, you can swap sensors at will without having to manually re-calibrate anything.
Just thought I would chime in here and add some things. If you have any questions let me know and I will post the answers.
O2 sensor placement is very critical to the life and performance of a sensor. Like someone mentioned before having the sensor very close to the turbine outlet is the best however the heat generated from doing this will kill a sensor. That is why AEM designed and produce their Finned standoff design when they produced their 4-channel wideband to both protect the sensor from overheating and to move most of the sensor out of the path of the exhaust to prevent restrictions.
Another thing is the angle of which the sensor is installed itself. There is a very specific angle that you have to have the sensor installed at or you will get a premature failure. If you look at any factory exhaust it will always be within this range when installed.
Another thing to mention is the sensor element itself. Lets see if I can explain this for everyone to understand. The sensor element on the Bosch units both 4.2 and 4.9 is made up of a bunch of tiny holes that sense the exhaust gas. So lets just say its like a sifter.
When you run rich or have contaminants in your gas. Whether it be oil from the turbo system you just installed or simply leaded fuel these holes will start to get plugged up and cause the sensor to fail prematurely. Yes the sensor will last 10 years on a factory car because that vehicle is always running in an optimal tune with O2 placement where it needs to be. Your car although you may think runs fat dumb and happy may be killing the sensor and you dont know it.
Everything you said about the sensor resistor is true. AEM uses the calibration in the sensor itself for readings however in their new X-Series wideband you can choose between the normal resistor style and also do a free air calibration. Now remember when doing a free air calibration the sensor must be removed from the exhaust and in fresh air environment without lingering exhaust or chemical fumes. I can go into the benfits of both of these types of calibrations if you would like
to show if your car is running at optimal tune.
and no again because a lot of stock cars are running far from optimal tune due to lack of maintenance.
what you posted is correct but that's only one part of the failures
this post is about the other issues related to the actual design of the sensor and controller. and the first article actually explains a lot of the causes for failures that follow incorrectly programmed controller that doesn't do the job of running the sensor properly which seems to be improved with 4.9lsu but still not fully functional because the controller is not integrated into ecu
I'm reading more about this and more I read more I see that the cheapo aftermarket wideband kits are not made to last.. sometimes you get lucky tho
I started this thread to share what I found while I was trying to figure out why sensors keep going out on mtx-l its allover the internet. and I found what I'm looking for and shared here as well...
sorry my previous post came out a bit harsh lol i hope you don't take it too seriously Rtype
what else i found
lsu 4.2 units are found in a lot of german cars especially VW and audi, sometimes Volvo with a different connector( confirmed that myself)
lsu 4.9 connectors are according to some people same as VW throttle body connector.(not confirmed yet)
For the past year I've been trying to explain to people why the LSU 4.9 is worth it, and I'm glad I found this thread! My LSU 4.2 is dead and lasted maybe 3 years with occasional leaded fuel use and lots of tuning. I'd be plenty happy with 5 years out of the 4.9.
you need a new cable if you want to use LSU 4.9 on the MTX-L but it is possible. around 100 bucks for a new cable and sensor.
I killed my MTX-L o2 sensor. 100% my fault. When i first got my car running I had a TON of parameters to set and alter with the engine off. unfortunately that cooked the O2 sensor and it's basically dead now. Jumps all over the place, freezes up at weird AFR's, and gives E8 most of the time. Too lazy to replace it since it didn't start acting up till thankfully i had my tune finished.
I should've added a simple on/off switch to the MTX-L so I could cut the power to it when the engine isn't running and ****.
well my 4.9 is coming in a few days and im gonna go and check to see if i can find a vw throttle body connector at junkyard to confirm that they are same
If they are then its free lol
And just 60 bucks for 4.9 sensor
part number 17025 for lsu 4.9
Part number 17014 for lsu 4.2
Im not a cheapass i just like recycling what i can and using the sht out of it until it dies beyond dead
also results are in for o2 sensor cleaning
Carb cleaner/ gasoline other solvent that doesnt corrode the sensor element works for light contamination like oil etc
Boosting it out lol dont have boosted car but again its same as gasoline cleaning only at full temp
Torching the sensor until red hot had no effect at all, burned off the black soot on the outer skin but i dont think it ever got to the element
And theres a slight chance of overheating and melting it since propane burns at almoat 1800 degrees way above sensor operating temp.
Also managed to burn both my hands as i was putting the torch away(dumbass , it was just like in the movies too)
Ravex3m did not take it harsh at all. I was just pointing out that there are other reasons as well for the sensor fail. Not just the one you mentioned. The heating control of the sensor is very important.
Also on a side note m4xwellmurd3r just make sure you never leave the sensor off with the engine running. This will also kill a sensor.
Hopefully you get lucky and the pins are the same, so you can just repin over to the new shell. You can also buy a plug & pin kit for <$20 so you don't have to splice. I'm not a fan of pigtails.
02-05-2016, 11:26 PM
Wideband Bosch LSU 4.2 versus 4.9
