A/F Meter by Dawes Devices

A Dawes Devices four-color LED A/F indicator is custom-installed within the 93 Gen-2 dash cluster, in the blank space normally used by the automatic transmission indicator, just below the fuel gauge. It is used to monitor "upper-range" or the rich-end of the A/F scale. Voltage readings from the 4-wire (heated) Oxygen sensor are most meaningful only during Wide Open Throttle (WOT) (when the ECM is in open-loop mode. 

Darren Dawes has developed a unique WOT approach. Rather than constantly flashing multiple LED bars, as most digital A/F indicators show across the entire A/F scale, (from 0.01 to 1.00 O2 sensor volts,) the Dawes meter concentrates its resolution at the critical upper-voltage or RICH end of the A/F spectrum for monitoring WOT operation. 

To better understand how the Dawes meter works, see the chart below (note that O2 sensor output voltage is dependent on exhaust gas temperature). Just remember: TOO LEAN is MEAN, FUEL is POWER. Running an turbocharged engine at Wide Open Throttle and getting NO Dawes LED's to light (or the RED LED) is very bad news.

A properly tuned turbo engine should make its best power with either the GREEN or YELLOW LED on at WOT using the Dawes A/F indicator. You can essentially ignore the Dawes A/F Meter at  any throttle opening other than WOT.

(Note: The fourth RED-LED is not shown lighted in the photo below. The camera exposure caught three of the four LED's pulsing in rapid transition.)  See Analog Air/Fuel Ratio Gauge below:

LED Color BLUE GREEN YELLOW RED NO LED on Sensor vDC 1.00 to 0.98  0.98 to 0.94 0.94 to 0.90 0.90 to 0.78 less than 0.78 ~~A/F Ratio 11.5 to 11.7 11.7 to 11.9 11.9 to 12.1 12.1 to 12.9 greater than 12.1 WOT Relative too RICH <<<<< >>>>> too LEAN very bad news!

 

Auxiliary Gauges by Westach.com

Tachometer	Pyrometer (Exhaust Gas Temperature)
Lower gauges replace useless cup holder/ashtray and include tachometer (0-7000 rpm; left). The Westach tachometer (Left) features an adjustable calibration potentiometer and was dialed-in with a Mopar DRB scanner; accuracy was verified on the DynoJet dynomometer. On the right is a dual-combination vacuum-boost (30-0-20) meter with integral Pyrometer Exhaust Gas Temperature  (400 - 1800 degess F). In my opinion, the EGT is the single most important gauge you can install on a turbocharged engine. Don't boost without one!	The EGT thermocouple probe is installed upstream of the turbo in the exhaust manifold.  How a Pyrometer Operates: A pyrometer is an Exhaust Gas Temperature (EGT) gauge that allows you to read an immediate change in exhaust temp by receiving a signal from a probe (thermocouple) that is inserted into the exhaust manifold. The monitoring of temperature alerts the driver of a problem well before you would receive an indication a cylinder head water temp gauge. A high exhaust temp reading can be a result of: Improper fuel octane or lean fuel conditions. The #1 enemy of superchargers or turbochargers is excessive heat. Bad fuel or water in the fuel, either of which will result in engine detonation. Worn, defective or clogged injectors, cylinder or piston cracks, intake or valve problems. Pyrometer Terminology PYROMETER GAUGE HEAD - the instrument dial or digital readout  which is typically mounted in the dash. Various ranges are available with a 400-1800°F range chosen here. THERMOCOUPLE - this is a K-type thermocouple sensor probe that reads the temperature. Thermocouple generate their own signal and do not require power to operate. THERMOCOUPLING WIRE - a special wire that carries the signal from the thermocouple to the gauge.

Dual Charge Air Temp Gauges (measures intercooler efficiency)

In photo below, the top dual-gauge monitors Charge Air temperatures (both intercooler inlet and outlet temps, range from 50 to 325 degrees F) to determine intake manifold charge air cooling efficiency. By monitoring the intercooler inlet/outlet temps, one can easily spot any adverse affects, such as heat soaking and any other adverse effect on intake manifold charge air temps, such as ambient air temperature or over-boosting. The two thermistor-type, air temperature sensors are mounted in the appropriate Charge Air )intercooler) pipes.

Analog Air/Fuel Ratio Gauge

Lower analog A/F gauge is handy, as it tends to dampen (react more slowly) to the closed-loop oscillations of the ECM and (4-wire or heated) O2 sensor. The analog A/F gauge also acts over the full O2 sensor voltage range (12:1 - 17:1 A/F ratio), whereas the Dawes LED A/F indicator is geared toward a more specific, narrow-band (11.5:1 - 12.9:1 at WOT) indication.