theformula

my Intellitronix digital air/fuel ratio gauge isnt reading! Its illuminated where it says RICH LEAN but the bars dont come on. I checked everything. I re-did wiring with new wires ...Checked the ground. Spliced it into the o2 sensor wire, spliced it into the wire that goes to the ECU. Still nothing.

I'm wondering if its the Bosch 02 sensor I bought that might be bad. But how do you tell? The car would go into limp home mode with a faulty 02 sensor right? And it would run excessively rich? I verified FP at 47psi. Right where I left it.
any ideas?


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91 Formula
305 TPI 5speed
1LE/G92/WS6
Custom cold air intake w/K&N, SLP airfoil, ported plenum, TB coolant bypass,Crane AFPR (47psi),94 octane,Crane Extruded Alum. 1.6 full roller rockers, Timing set from 4*BTDC to 10*BTDC,MSD6AL, Holley 9mm Annihilator Laser shot 50 wires, Ac Delco cap,rotor and plugs, Bosch O2sensor, SLP 1 5/8 headers,SLP catback,3:73s,JET 195* fan switch, Macewen white face gauges, Intellitronix Digital Gauges

Stock throttle body, runners,intake manifold,cam, and heads.

Tim Burgess

You could check the A:F meter by connecting the positive side of a 1.5 volt cell to the input of the meter that normally connects to the O2 sensor. Connect the negative side of the cell to ground. 1.5 volts should make the bargraph read full scale (rich). Likewise, grounding the input of the meter should make the bargraph read low scale (lean). Also, you could use a 10K ohm potentiometer (from Radio Shack) across the 1.5 volt cell to vary the voltage to the meter to test the input voltage versus bargraph reading.

Here are some A:F mixture ratios that correspond to the O2 voltage outputs listed:

17:1 141 mv
16.5:1 202 mv
16:1 260 mv
15.5:1 320 mv
15:1 390 mv
14.7:1 422 mv
14.5:1 450 mv
14:1 515 mv
13.5:1 580 mv
13:1 645 mv
12.5:1 715 mv
12:1 790 mv

14.7:1 is the stoichiometric A:F ratio for gasoline.

Tim

theformula

Thanks Tim. Turns out it was a faulty gauge. Im swapping it out for the Autometer one.
Thanks