Screwy MTXL or???

[Roadrunner]

So I have noticed recently that my MTX-L wideband has been displaying a bit weird and wanted peoples thoughts on if its the unit or something else engine related.

When driving home last weekend I noticed the display was pegged at 22.4 all the time. Idle, cruise, acceleration - always at 22.4.
I don't trust this reading, as I imagine at 22.4 the car would barely idle let alone run, but the car runs perfect like always. No audible pinging or spluttering etc. But after a fair while of driving, it slowly displays in the normalish ranges, but sometimes doesn't display full lean on overrun (like the injectors aren't cutting out)

Last night went for a drive. Car runs like a dream but, AFR pegged at 22.4 until:
at 15km of driving I start getting a cruising reading around 18.0 without change at full throttle or zero throttle (no overrun?? just swings between 18.1 and 19.5).
at 20km cruising is now in the normal 15.0 range and going down to around 11-12.0 under hard throttle (displaying like normal) except when I let off throttle (over run/injector cut off) it doesn't display full lean/injector cutoff, or it takes about 4-5seconds for it to display full lean (normally goes full lean instantly).
I also notice just the subtlest single hesitation just as it eventually goes full lean/overun.
On the way home after dinner, displays perfectly normal ranges (though the overrun lag still persists and sometimes doesn't display full lean at all during zero throttle over 1500rpm. It will display in the 13.5 range.)

Searching seems to suggest that the 22.4 all the time reading is a bad sensor, but this was a new sensor last year when the ECU was installed. (the MTXL unit is second hand though) so I'd like to think this isn't a faulty sensor already. No error codes.

I have had a few people tell me that they can see spluttering exhaustsometimes coming out on deceleration (engine braking down a long hill) so I'm wondering if the reading (22.4) is actually correct at the sensor and this is causing the ecu to dump fuel, making the engine run fine albeit a bit rich??

Would an exhaust leak or something else cause this reading at the sensor?

Car is going in for a service next week but I've looked over and the only thing I can see is a bit of exhaust soot on the engine block near the dip stick.


Don't know if this is new or not or if this is even big enough to cause false readings.

If the sensor (or MTXL controller) was faulty does this sound like normal behaviour?

Thoughts?

[NitroDann]

It could be a leak.

[Roadrunner]

That's what I was thinking as it seems to get better the further I drive (heating up closing the leak?) or the heater element in the sensor/controller not working properly, again fixed by driving further heating it up. But I'd have thought a faulty heater circuit would throw an error on the Mtxl display.

[Dan]

This seems obvious but you didn't mention doing it, have you do a free air calibration of the sensor since you started having troubles?

I've had an innovate device not hold calibration. I was advised from a pretty knowledgeable tuner that they can sometimes go out of calibration or 'lose' their fuel setting so he advised me to should connect it to a PC and use LM Programmer to set the fuel setting to gasoline, after I did that I've had no more problems

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[smy0003]

Calibration?
Leak?
Grounding issue?

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[rascal]

I vote for needs calibration also.

My MTX-L has show same symptoms as this a couple of times in the last 4 years I've had it.
Each time a free air calibration has fixed it.
Its an easy 5 min job, so def worth trying even if it doesnt end up being this..

[Nevyn72]

Car is going in for a service next week but I've looked over and the only thing I can see is a bit of exhaust soot on the engine block near the dip stick.

Don't know if this is new or not or if this is even big enough to cause false readings.

It may not be related but needs to be addressed...... The SE is notorious for self-loosening exhaust studs and nuts.
If left the manifold will warp and need to machined flat again.

[Roadrunner]

Ok so performed a free air calibration (yes I am aware I should have done this to begin with but I didn't think the symptoms fitted).

The controller/gauge is stuffed.

Disconnected the sensor cable, turned to ignition. It did the normal procedure.
Connected the sensor, did the htr part then it started powering off then on again repeatedly.
Turned it off. Restarted calibration procedure again.
This time got to htr and then CAL then randomly restarted again doing the start up full sweep etc a few times. then showed 22.4.

Though hmm, no that's not right lets do this one more time.
This time doesn't even get to CAL part, just randomly reboots, flashes e9 (low power) and then goes full freak out only showing the first number 8.

Now the gauge is completely dead. No display, won't turn on at all.

I'll post a video when it finishes uploading to YouTube.

[NitroDann]

Or install fault.

[Dan]

Or install fault.

Yep.

So now with the sensor disconnected and power applied it doesn't even show the 'E2' error?

Innovate's are pretty sensitive to voltage, since it showed a low voltage error have you tried starting the car with the sensor disconnected to see if it's a problem with voltage from the battery?

If it still doesn't show anything I'd probably pull it out of it's mounting and connect it directly to 12v power to see if there might be a problem in the wiring.

[Roadrunner]

Well this is embarrassing lol

Went back to the car to give it one more go.
Still nothing but noticed my boost gauge isn't doing its startup sweep either.
Check the fuse. Blown.

Replace the fuse and the mtxl comes but but freaking out again.
Wiggle the power cable and it works! I held the cable at the right angle for long enough for it to do a calibration just in case.
Bit more sloothing, Turns out the solder join from the gauge was cracked and making intermittent contact. Gentle pull and the cables came straight out of the heat shrink.

Stripped and resoldering now but looks promising.

[Dan]

Good to hear

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[Roadrunner]

For what it's worth, here's the video of what I was seeing.

You can understand why I was freaking out lol

http://youtu.be/H6Sx4j01SLg

All good now. Calibration done, just got to put the sensor back in and take it for a drive and see if that's sorted my original issue

[Roadrunner]

Hmm no luck.

After I re-installed the sensor etc. Kicked the car over idled instantly after warm up at 11.3. Fine.
Revved a little, bounced around but instantly dropped back to 11.3 Thought I'd won. gauge reaction time was super quick.

Well no.
Took it for a test drive this afternoon. Start the car: 18.something
As it idles progressively gets leaner till its showing 22.4 constantly.
Cars running fine. no odd sounds.
Drive up and down the street for a while and then it comes alive. Reading 13 something under acceleration and 15odd on cruise but still not going full lean on overrun.
Cruise around a bit more, starts creeping up to 18ish on cruise. Pull over. Restart the car just for the hell of it. It's idling up around 19-21. As I start to drive goes full 22.4 and stays there all the way home.

Ideas?
The only thing I can add is under deceleration/engine braking there is just the faintest of random pulsing hesitations.

[smy0003]

Try changing the ground to the ecu ground near the TB. It's the recommended ground, and it's a 5min job to extend the wire.

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