AEM Wideband Gauge with Failsafe Installation on 2005 GMC Savannah 5.3 with a custom turbo system.
Recently we had the pleasure of testing out AEM’s new UEGO Wideband Failsafe gauge. Uniquely enough our vice president had a turbo’d van that was in desperate need of a wideband gauge and this not only offered a sollution to our problem but more importantly offered a way for the car to act on a potentially harmful AFR scenario by lowering boost automatically.
The Wideband FAILSAFE Gauge is a Universal Exhaust Gas Oxygen (UEGO—“you-way-go”) controller with an internal boost sensor, an internal data logger and a full color Organic Light Emitting Diode (OLED) display. It includes technology to activate a failsafe strategy in the event AFR falls outside of a user-defined operating window. If the AFR falls outside of the set operating window, the Wideband FAILSAFE Gauge triggers a user defined output function that can save an engine from catastrophic damage.
WHY YOU WANT ONE
This product is a must have for all tuned performance engines, either forced induction or naturally aspirated, fuel injected or carbureted. Any high performance vehicle owners who want a highly accurate AFR tuning tool with logging and a protection strategy that can save an engine from catastrophic failure will want this FAILSAFE device.
WHAT IT DOES
After the engine is tuned and a safe operating window of AFR is established, the Wideband FAILSAFE Gauge continually monitors AFR and boost or vacuum to make sure that AFR does not fall out of the defined operating window at a given boost or vacuum level. If the Wideband Failsafe detects an out of range AFR reading, the gauge triggers a low side output (ground signal with a 1.5 amp draw max) that can save your engine from catastrophic damage.
The contents of the AEM Wideband Failsafe Gauge are as follows: assorted wiring, o2 sensor, gauge, install manual, spare gauge faces, stainless steel o2 sensor bung, vacuum tee, zip ties, and a usb extension cable.
We started the install by utilizing a boost control solenoid as the failsafe unit for the system. The reason we chose this method is because it was the simplest and most effective way to use the failsafe on our particular stock ecu/ems vehicle.
The solenoid acts as a boost controller bypass. When the failsafe parameters are met, the AEM gauge outputs a ground for the solenoid. This opens the pathway through the solenoid and bypasses the boost controller. This will lower boost back down to a safe and manageable wastegate spring pressure. (installation photo shown below)
Wiring to the solenoid is very straightforward. Blue wire from the gauge (failsafe ground output) was run from the interior of the car, through a suitable grommet in the firewall and connects to one wire at the solenoid (polarity does not matter). The other side of the solenoid wiring goes to the positive terminal of the battery which in this case we used an “add-a-circuit” fuse holder on the horn fuse in the engine bay with a 3 amp fuse for the solenoid itself.
The next step of the installation was adding the wideband o2 sensor to the exhaust stream. Our vehicle already had an unused bung in the ideal location (about 18” from the turbo exhaust housing at a 20deg angle upwards). So we simply just had to thread the sensor in. (shown below) wiring was run through the same grommet used in the installation of the failsafe wiring and then to the gauge location near the instrument cluster on the steering column.
The following photo shows the wiring route through the tunnel with the engine cover off - which later passes through a grommet on the firewall/tunnel and into the cabin.
Wires were then run through the dash and up to the steering column where they end at the gauge location. At this time the main wiring for the gauge and also the included vacuum line were run up from under the dash to the gauge location. The vacuum line was then tapped into the source vacuum for the boost controller at the intake manifold.
Gauge installation was next. Plugged it in and installed.