Anyone installed the AEM Digital AFR gauge in a 930?
 

Hi Everyone,
I recently purchase the AEM Digital AFR gauge from the Pelican Parts forum. I unwrapped the packaging and noticed the cable that connects to the O2 sensor and goes to the gauge is 12 feet long. Is that enough length? I plan to run the cable from the engine bay through the shifter tunnel to an area near the ashtray.
I know the common logic is to add a stub to the existing cable, but coming from a EE background, 12 feet is about the longest distance recommended when running with voltages in the 5 volt range.

So, bottom line is anyone running the AEM gauge/wiring scheme with any issues?

Thanks in advance,

I run two of them, one for each bank. The wiring supplied with the kit was not long enough for my setup. I simply added more wire, soldered it, and called it a day. Both gauges work very well and I have no issues.

Oh great, you're an EE and recommend staying no more than 12ft? Mine is at 18ft (added 6ft) to make it around engine compartment.

Is the accuracy compromised??

Well, from a "retired" EE, it depends...;)

If the line is 5 Volt TTL, 10 ft is the recommended max distance. 12 volt direct current is a bit safer. As long as the sensor and gauge are calibrated with that length it uses, it should be safe. If you look at the chart provided with the kit, it deals in "tenths" of volts. Excessive cable length could quite possibly cause of tenth of a volt loss. So beware.

Update:
I spoke with AEM Technical Support on Monday and they suggested not to add an additional length of cable to the existing cable. While the length I wanted, 16.5ft., was pushing it, they suggested fabbing a new cable. He provided the part numbers for the pins for the connectors in the thread I started on the AEM Products BBS.
AEM Cable harness Thread

If you wish to purchase a cable, Bisimoto is going to be offering these cables for a nominal fee. I also wish to thank Bisimoto for his outstanding support in the products he sells. Much appreciated.

So if I get you right, AEM doesn't see a problem with voltage drop and thus calibration with an extra 4+ feet? I can understand their direction not to add/splice in the extra length, but with good soldering skills I don't see the issue. Maybe just use a heavier gauge wire, keep the V drop to a minimum?

If I recall I spliced in some extra length on my Innovate installation. Seems to work, who knows if it's accurate, I haven't blown any holes in my pistons yet, so assume all is well.

If you read the thread on the AEM BBS about lengthening the cable, he replied "theoretically no". The problem with soldering or crimping an additional stub in is that the joint(s) is more resistive than a solid copper strand(s), no matter how good the joint is.

So the only effect is; any voltage drop due to the additional length is going to be interpreted on the rich side of Lambda. No holing pistons from that, anyway.

Thanks Dave, we need resident EE's to keep us straight. To be honest, I can't remember if the lead was long enough with my Innovate or not, or if maybe it was the electronic boost gauge wire(s) from the sender that I had to lengthen. Either way it's good to know which side of the AFR calibration that extra resistance will impact. Correct, a single run of wire is much better than splicing for the reasons you outlined.
My daddy done taught me to solder and a bunch of stuff about electricity and electronics, but just rudimentary scratching the surface. A couple of college courses and intuitive understanding is about as far as I go in this arena. Give me a VOM and I=E/R and I'm good to go!!

Mark,
Our dads must have been a lot alike. My dad got me into electronics much the same way. Things just got a little out of control when I started tearing the stereo and tv apart to see how they worked. :)

Since most of are running high 11's or low 12's AFR anyway, not much of a problem. But if someone is targeting Lambda while cruising, keep in mind the gauge could be a tenth lower than what is actually at the sensor.

I am running one one one of my race cars and bought one for the Slantnose. I extended the wires on mine, when I called AEM about doing this 4 years ago, they told me to go ahead, so I did.

Dave, thanks for the legwork on this! Did AEM mention the magnitude of error we could get on a per length basis? I need like maybe one extra foot to get past the turbo outlet.

Dave, BTW, I just redid mine to get out of the shift tunnel. There is way too much crap packed in there. I drilled two 1" holes and grommeted them, so I can fit all of my electric wiring through the passenger side. Holes are in the kick panel behind the passenger seat.

Hi Patrick. No, there was no mention of signal loss on a per foot basis. Are you planning to mount the sensor between the turbo outlet and the muffler input?
For sensor longevity, I would recommend placing the sensor further downstream, but not too far where ambient air from reversion could cause false readings.

Dave, the old location on my BAE setup was in the line before the turbo, and it only read the left bank of cylinders. As I have rerouted the wiring, it may reach the new location without lengthening. I am going to try and get the sensor about a foot downstream of the turbine outlet. If I have to lengthen it, I will increase the wire sizes to cut the voltage drop.

I'm no EE, but I extended mine. When I called AEM about having to lengthen the wire, the tech told me to make sure and add the extension on the gauge side, and not the sensor side. So, I ran the the cable that came in the kit, from the sensor to just inside the cab, cut the gauge plug off, and soldered a 4-5 foot extension on. It all seams to work fine. To be honest, I'm not sure how "dead-nuts" accurate it is. I have a Zork tube, and I've read on here that Zork tubes don't help O2 sensors give 100% accurate readings. I added the gauge after I had the motor rebuilt. The shop tuned the AFR's before they gave it back to me, and the readings I do get from the gauge are well within range of what their supposed to be.

Thanks, Dave, for the kind words, and support. Your custom cable is coming soon, and goodluck on your project!