I've installed an Autometer Air/Fuel ratio guage, and once the system is hot, the guage is not consistant, while traveling a constant speed. sometimes to goes quite lean, flutters between lean & rich (which iI think is normal), and sometimes it goes blank. Is this normal? Thanks


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89 RS Camaro, LO3 305 TBI
Cooling Fan Overide Switch
L69 Duel Snorkel Intake
Dynomax Ultra Flo SS Cat Back

 

Mine does it too, but ive been told by a couple people my ecm is going out, so im getting a new ecm and prom.

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1989 Firebird. Modded.
700r4-->t5 w/ram clutch
Cold air, 1.6 rockers, 21lb injectors, 3" y-pipe, random tech cat, 3" ipipe, flowmaster 80 series 3" in 3" out hand made stainless tips, Lakewood LCA's, Msd 6a, Msd coil, Wonder Bar, 180* stat,
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In Memory of #3 Dale Earnhardt

 

In 89, you start to see highway mode inacted by the ECMs. The oxygen sensor reads a narrow band right around stoich, so when the car goes into highway mode, the gauge goes low or blanks out completely because the AF ratio has gone below the minimum range. This should happen when you're cruising at steady throttle above 55mph.

So that behavior is normal. It should come back up (out of highway mode) if you let off the gas or give it some throttle or drop below 53mph.

[This message has been edited by Jza (edited September 06, 2001).]

 

From Auto meter, apparently from the top image, the movement is 'normal'

http://www.autometer.com/hp/techtips/tips.html
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[This message has been edited by deadbird (edited September 06, 2001).]

 

lol. synchronized posting and editing..

 

LoL

 

it is normal. ive got one and its supposed to do that. it wont ever stay still once the ecm is in closed loop. bouncing back between rich and lean is ok. but if you are constantly bouncing around in only the rich or only the lean lights, then you have a problem. the only thing i use this gauge for is to watch it when i hit the nitrous, you wanna make sure your light stays just in the green at WOT with NOS

 

if the a/f gauge goes into an o2 sensor, which i'm assuming it does, this is normal, because on a fuel injected car, the a/f/ ratio constantly varies to keep the cat hot enough and for proper catalyzing. o2 sensor voltages constantly vary once the sensor heats up. this is what is referred to as "closed loop" operation. "open loop" is before the o2 sensor is hot enough and the a/f ratio is determined by the ECT.

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'84 Berlinetta, LG4, 700R-4, starwars interior, no major mods yet