Hello everyone. I have been having some reliability problems with my wideband oxygen sensors. I have an Innovate Motorsports MTX-L AFR gauge and a Bosch 3737 wideband sensor.

I've read on a few different forums that Innovate Motorsports has some problems with accurately controlling the temperature of the sensor and often overheats them, which is what kills them.

However, after reading through some documentation from Innovate, I have discovered that after 1300*F EGT, the gauge cannot control the heater circuit accurately.

So I'm wondering if my problem with going through sensors is from the gauge itself eating them up or if my EGT is too high at times. I don't have EGR, which I believe is used to reduce combustion temps. Maybe that is contributing to the problem.

Is there a way that I can cool down the sensor a little bit?

Also, are narrowband oxygen sensors prone to the over heating issue that occurs with the wideband? What would happen with an overheated narrowband?

Thanks.

 

I run an Innovate and have not had that problem. I do have a buddy with a Calloway C4 that has the same setup. He had to make a shield to protect the outside of 02 sensor for it to function properly.

 

..... Where in the exhaust is your WB O2S located ? ... it should be in the collector , or as far away from the cyl head as possible ... Wide Band sensors don't like to see exhaust temps over 900* ... my Hooker headers had the bung in the #7 tube about one foot from the head and the O2S was always overheating on my Innovate LM2 ... once I moved it to the collector all was fine ... I also discovered that with Innovate products you should hard wire the unit and NOT use the cig lighter plug for power ... too much RFI at the connection that interferes with the operation of the unit ...........

 

It is in the collector. I've had it all over really. I've had it in the collector at different locations, and down near the back of the transmission. Still same problem. Don't know why it keeps happening but it does display E8 after it malfunctions.

Typically what will happen is it will be working normally, and out of nowhere it will read max lean (22.4:1) for like 20 seconds. Then it will read 14.7:1 for 20 seconds without fluctuating around 14.7:1 like it should. And lastly, it will go to about 8:1 for another 20 seconds. This happens in that exact order, and then sometimes it will continue reading actual AFR, other times it will display E8. I know this is a false reading because the engine still responds normally when this happens.

I've been through about 5 sensors in about a year. I had initially suspected something was wrong with the engine, like a misfire, possible head gasket leak. But over the course of the last year I have completely redone the ignition system a few times, and changed the head gaskets 3 times. The engine performs way too good now for me to suspect any problems, and the dyno also showed it was healthy.

That leads me to suspect that the EGT is high. I have continued doing some research and a lot of people are saying that Innovate is not as good quality as I initially thought it was.

Also, my gauge is wired off of the accessory power wire inside the drivers side dash. The pink wire with white tracer. And I think I have it grounded to one of the main ground wires inside the car. The one that grounds on the rail on the drivers side. I have a couple other things also connected to those wires, and I haven't experienced any problems with those.

 

Just a side note-
The 02 sensor should NOT have power applied unless the engine is physically running or the sensor will overheat and damage itself.
If you have it wired on 'Accessory' and spend a lot of time listening to the radio or whatever with the engine off, that could be a potential issue.

 

Good point. If the 02 sensor is hot when the engine is not running, when the motor is finally started, the condensation that has formed inside the primaries will hit the hot sensor and can kill it.

 

Is there some way I can control this so that the AFR gauge only comes on when the engine is running?

 

You may be able to wire an O2 heater circuit relay that only gets energized when there is engine oil pressure or wire it in parallel with the fuel pump relay?

 

Wow that is a great idea! If I hook it to the wire for the fuel pump, the one after the splice for the relay and oil pressure switch, would the 2 seconds of priming for the fuel pump hurt the gauge or sensor?

 

I doubt 2 seconds would be long enough to get it hot enough to be an issue. Besides, you would be normally starting the car at that point anyway.

 

Awesome. I'm going to rewire it tomorrow.

Also I am going to install the adapter that Innovate offers. I think it is called the HBX-1.