I have the autometer version and it fluctuates insanly. Is this just the way it is with the high samping rate? Its annoying. Do all of them do this?

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The A/F mixture ratio gauge should have a power, ground, and + and - O2 sensor inputs. The - O2 sensor input must be connected to the O2 sensor ground at the ECM, or noise will cause the O2 meter to give incorrect readings. If there is only one ground wire on the gauge (no O2 sensor - wire), then hook the gauge ground wire to the O2 sensor ground wire at the ECM. When the engine is cold, the voltage should be steady at around 0.450 volts (around 14.7:1 ratio) & oscillate between 0 & 1.0 volts, when the ECM has gone into the closed loop mode of operation.

Tim

 

I have a K&N A/F meter and had the same problem. What i did was to have a welder weld a bung just past the "Y" pipe and install a new GM one wire 02 sensor. I connected the gauge ground wire to the 02 sensor useing a large clip and connected the other wire to 12v. The meter lights settled down but were still pretty fast. I removed the GM one wire 02 sensor and installed a used Boush sensor (replaced under warranty) from a BMW dealer. This sensor was replaced because it was slow but sure worked nice on my A/F meter. The only problem is that the 02 sensor is mounted a little to far away and takes a awaile to get going. A heated sensor would work great but cost big bucks. Just my .02

-Auggie-

 

could this a/f meter be grounded to the car?? I'm running a carb now, no ecm, but the 02 sensor is still in the headers.

 

What wire on the ECM should i get the ground from?

Thanks

Tim

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Like i said i grounded my monitor right to the body of the 02 sensor.

-Auggie-

 

I'm not sure of the pin number in an '89 TPI setup, but here's the '87 & '90 - '92 TPI setup pin numbers - the pin numbers may be the same as the '87 setup & the wire colors should be the same in any case:

'87:
O2 positive wire: Connector C2, Pin D7, purple
O2 ground wire: Connector C2, Pin D6, tan

'90 - '92:
O2 positive wire: Pin E14, purple
O2 ground wire: Pin E15, tan

Tim

 

165 ECM O2 wires..

D6 (O2 GND)
D7 (O2 Signal)

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-=Jeff=-
89 Corvette Coupe White with Black Grand Sport Stripe
-=ICON Motorsports=-
Check out my mods on My '89 Vette

 

If I'm not mistaken, it is supposed to fluctuate, if it doesn't there is something wrong. The computer, during closed loop, is adjusting the a/f ratio to try and keep the O2 reading at .45V. The reading is very hard to keep constant, so the computer tries to keep the average reading around .45V. As long as the average reading from the gage is in the orange zone, don't worry about it fluctuating. I have one on my 85 Camaro and it is always bouncing between the lean and rich zones. Mine also has a tendency to go off the scale on the lean side but that's another problem.

-Dave

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Better to keep one's mouth closed and be thought a fool, than to open
it and remove all doubt.(Mark Twain)
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I have sorted out the ground and such. My issue was that it fluctuates a lot more than i anticipated. Mine also shows extremely lean when i am coasting... is that normal?

 

When coasting that's very normal.

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92 Z28 L98 350
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Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires.

Best ET 13.5@105 mph

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

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