I recently bought an AEM wideband for the LeMons car (1966 Volvo Amazon, 2 liter carbureted 4 cylinder) and after installing it, the gauge started reading what seemed like good readings, but after a minute or so of idling it pegged on the lean side and stayed there. I contacted AEM and they sent me a replacement oxygen sensor, which I installed, and the same thing happened- start the engine, get readings, then after a few minutes the gauge pegs lean.
I did the "brake kleen and rag" test and confirmed the sensor is bad. AEM has offered to send me one more sensor, but I'm just trying to figure out if there's something in my setup that's a problem. The bung is welded into the X pipe, where the 2 pipes from the exhaust manifold come together, about 3' downstream of the cylinder head. I bought another bung and am going to try welding it in a bit further upstream, in one of the pipes. I can't think what in the X pipe could be a problem though.
Thoughts?
Are you letting it sit with key on power before cold starting? Innovate's heater strategy doesn't like that and it kills sensors as well, where other controllers are fine. If you can only have the wideband on while the engine is running it could help. OR try a genuine Bosch sensor from a different source?
In reply to Paul_VR6 (Forum Supporter) :
The heater comes on as soon as the gauge comes on. AEM specifically says do not run the engine without the gauge powered up, but doesn't seem to care if the gauge is on with the engine off. To do the brake kleen test you remove the sensor from the bung and power the gauge with the engine off, with the sensor in free air, then apply a rag soaked with brake kleen, and the gauge should read full rich. This is AERs own test procedure.
AEM customer rep also told me they use only Bosch sensors.
Gauge/controller on and engine off and cold started is probably the #1 cause of sensor failure on the Innovate. If I wire them to only turn on with the fuel pump they last. Not sure if AER uses the Bosch chip or a proprietary heater circuit. I have never heard of them either..
Paul_VR6 (Forum Supporter) said:
Gauge/controller on and engine off and cold started is probably the #1 cause of sensor failure on the Innovate. If I wire them to only turn on with the fuel pump they last. Not sure if AER uses the Bosch chip or a proprietary heater circuit. I have never heard of them either..
Helps if I get the name right. It's AEM.
https://www.youtube.com/watch?v=rmnxKLjM25g
https://www.aemelectronics.com/products/gauges/wideband-uego-air-fuel-gauges/digital-wideband-uego-afr-gauge/digital-wideband-uego-afr-gauge
I run the AEM, and the heater circuit starts as soon as the gauge has power. At least how I have mine wired it does.
Seems to me that if sensor 2 failed that quickly, there may be a board problem. Since you know cold cracking is a problem, it's quite unusual to repeat that so quickly.
(and its not a great thing that cold cracking is such a common problem- we rarely broke sensors that I bought over 20 years ago when testing at -20F, so for these boards to be that bad....)
alfadriver said:
Seems to me that if sensor 2 failed that quickly, there may be a board problem. Since you know cold cracking is a problem, it's quite unusual to repeat that so quickly.
(and its not a great thing that cold cracking is such a common problem- we rarely broke sensors that I bought over 20 years ago when testing at -20F, so for these boards to be that bad....)
Do you mean a board problem in the gauge, or in the sensor?
In reply to volvoclearinghouse :
Gauge. Getting two bad sensors that quickly would be very unusual.
Trent
PowerDork
2/28/23 1:51 p.m.
You aren't running leaded race gas are you?
When I have to tune a race car on the dyno, I bring two or three sensors along since it kills them pretty quickly.
Thanks for the feedback. I've emailed AEM and offered to send the gauge back for them to check.
Trent said:
You aren't running leaded race gas are you?
When I have to tune a race car on the dyno, I bring two or three sensors along since it kills them pretty quickly.
Nope. Regular old 93 octane pump gas. I pulled the sensor and it's clean- not any carbon on it nor any physical damage.
From AEM:
"We unfortunately no longer have a repair/service team to inspect your current gauge if you were to send it in.
Although it typically is not a gauge issue, I’d be happy to set up the warranty claim to send you a new gauge and a new sensor. Both will be tested before shipping.
If you are okay with proceeding with a replacement gauge/sensor, please provide proof of destruction on your existing gauge/sensor so we may process replacements. See attached images for an example"
That's crazy. Cheaper for them to just mail out new gauges. Geesh.
In reply to volvoclearinghouse :
Didn't you just get it? Should be covered since it's been failing sensors like that.
We have had good luck with the AEM in general, at least as far as sensor life goes. Analog voltage offset is another topic though. Glad they're taking care of you.
For evidence of the gauge destruction, I sent them thus:
Cinder block.
I got the new gauge and new sensor in the mail about a month ago; I had the car sidelined for some other things and so just recently got them put in.
No difference. I start the car, the gauge goes through its initialization sequence, then starts reading, and the gauge eventually pegs out at "--" on the lean side and won't change.
I'm really frustrated at this point. I've been through 2 gauges, 3 sensors, several emails with AEM, and it just won't work. I even tried welding in a new bung, closer to the engine, and it did the same thing. The new bung is only about 20" downstream of the exhaust output of the head, on one of the pipes. The sensor is pointing straight down in this installation.
AEM doesn't know what's going on, but they've basically pulled the plug at this point. I followed the directions, and I'm not exactly an inexperienced wrench-turner. I electrically isolated the gauge on it's own dedicated circuit to the battery. What the berkeley is going on with this thing? I drove the car yesterday, and it runs fine, accelerates well, seems to have good power, doesn't overheat, and isn't smoking.
I'm pissed. I'm out $200, and I don't have a functioning gauge. Really berkeleying irritating.
In reply to volvoclearinghouse :
If the car runs well, and has no obvious hesitations or whatnot, then the sensor is delivering bad information for sure- so just focus on it.
Hopefully, some AEM experts will walk through what's going on- but it almost sounds like the wiring from the gage to the sensor is bad. Hopefully, something simple like the heater is the problem.
alfadriver said:
In reply to volvoclearinghouse :
If the car runs well, and has no obvious hesitations or whatnot, then the sensor is delivering bad information for sure- so just focus on it.
Hopefully, some AEM experts will walk through what's going on- but it almost sounds like the wiring from the gage to the sensor is bad. Hopefully, something simple like the heater is the problem.
The new gauge came with a new wiring harness, so to be on the safe side, and since I was running the O2 sensor to a new bung anyway, I used the new wiring harness, too.
Is the heater controlled by the gauge?
Isn't it possible to use different scales with the AEM based on fuel type? If so, do you have the wrong fuel type selected?
Is it possible it actually is that lean at idle?
volvoclearinghouse said:
alfadriver said:
In reply to volvoclearinghouse :
If the car runs well, and has no obvious hesitations or whatnot, then the sensor is delivering bad information for sure- so just focus on it.
Hopefully, some AEM experts will walk through what's going on- but it almost sounds like the wiring from the gage to the sensor is bad. Hopefully, something simple like the heater is the problem.
The new gauge came with a new wiring harness, so to be on the safe side, and since I was running the O2 sensor to a new bung anyway, I used the new wiring harness, too.
Is the heater controlled by the gauge?
Unless there's another box in the system, yes the gage controls everything.
wvumtnbkr said:
Isn't it possible to use different scales with the AEM based on fuel type? If so, do you have the wrong fuel type selected?
Is it possible it actually is that lean at idle?
I checked all the settings on both gauges. Both were set correctly.
It's showing lean under all conditions, and off-the-scale lean, which would be over 18:1. I drove the car 8 miles yesterday, the gauge pegged at "--" the whole time. Car ran fine.
At idle I tried putting the chokes on, and even with the engine coughing black smoke, it still read off-the-scale lean.
@alfadriver: no other boxes, just the gauge, the power wiring harness, and the sensor harness.
In reply to volvoclearinghouse :
So just to clarify, did they send everything including a new sensor, or just the gage? (the gage does everything important, BTW, which is what I would expect)
Which is a way of asking- where did the sensor come from?
I'm going to assume that your engine/exhaust system is solidly grounded to the chassis via a good wire- but that should not really be needed for modern set ups- the heater goes totally through the controller- which you have mentioned is wired as directed.
The reason I bring up the heater is that the output is as if the sensor is totally dead- which 99% of the time can be focused on the heater. It's possible that other lines are broken which will also give you a fault like that. One thing you can do (maybe again) is to check continuity from the sensor connector to the gage connector- since it's a simple harness, the wire colors should be identical on one end and the other. Sadly, doing the same with the sensor isn't something that can be done.
