josh greene

I installed a AFR gauge the light turns on I got power but I get no readings. I hooked it up to the wire comming off the O2 sensor.
Could my O2 sensore be bad???
do I have to hook it up to the ECU wire???

Thanks

coldfire

iTrader: (1)

yeah, most likely the O2 sensor. it happened to me also. just go ahead and hook up a voltmeter to the O2 sensor while the car is running. from what i have seen, usually when the sensor is dead you will get very low voltage readings...

if you are just looking for a narrow band O2 sensor, they can be had for very cheap. i believe the Bosch one is under $30.

- Aaron

iceblue

Send the blinky light gauge back. It is not going to do you a bit of good.

Take $400 and buy a wide band if you want a AFR reading.

josh greene

the gauge was cheep I just wanted to see if i was running sickly rich. I cant afford a wideband at this time.

coldfire

iTrader: (1)

you can actually tune cruise pretty decent, if you have an actual number or voltage reading.
this is because the narrow band is still quite accurate around the 14.7 range.

anything else though it will be basically binary "lean" or "rich" relative to stoich.

and is it not possible to get a wideband kit for around $300, if you get one of the DIY ones?
i forget where they sell them...

regardless, the poster was just asking why it wasn't reading, not how accurate it would be.

J-Rat

iTrader: (2)

^^^

Agreed. THat gauge is worthless for tuning, but I have one in my car because its a great tool for tuning for cruise. Why is that? Because you an see the "dithering" (gauge sweeping back and forth rapidly), which indicates that the 02 and the ECU are working together for the cruise mode.

coldfire

iTrader: (1)

yes, assuming that you are still running the stock ECU closed loop mode you will see the oscillation. but if it IS in this mode you can't really "tune" anything, right?

i seem to think that leaving the O2 disconnected to run in open mode, and so using fuel correction with your piggyback AFC, would be better, but maybe not...depends on your exhaust system also i guess (cats or not)

- Aaron

J-Rat

iTrader: (2)

Your mixtures will still effect the ability of the ECU to go into that mode. Its a tunable feature.

HAILERS

Somewhat related: you can buy one of those 12vdc LED's at RadioShack and connect it to the green six socket CHECK CONNECTOR. The red or positive wire of the LED to the socket with the BLACK/WHITE wire and the other wire of the LED to the socket with the YELLOW wire.

Then go for a ride. The LED should light up solid red. When you are cruising at a steady speed (above about 20mph) the LED will flash at something like three or four flashes per second. Let off the throttle and the LED will go blank then come back solid red and start flashing when you start driving at a steady speed again.

Generally the closed loop only works up to about 3500 rpm in any gear.

josh greene

I have a Rtek 1.7 would that make any dif? I wouldnt think so since you can use a wideband with them, Im using it just as a safty feature to make sure see if Im running really rich(I think I am) and so just incase for some odd reason I start running really lean I can actuall see it.

HAILERS

The RTEK shouldn't make any difference. You have to be careful when connecting to the 02 sensor wire. It is a shielded wire. You only connect to the center conductor. If you get any of the shield strands mixed in with the center conductor you ground out the signal from the 02 sensor.

On a 87car the 02 signal goes to pin 2D. That is the middle plug on the ECU. Looking towards the ECU its on the bottom row, second wire over from the far right. It's supposed to be a grey wire. NOTE: the shield usually ends about six inches from the ECU plug, so maybe it's not your problem.

Hey, what you might try if you don't have a meter, is go to the engine bay, pull the 02 connector off the sensor. Now connect your wire to the connector on the sensor and the other wires to where ever they go and start the engine. You should be able to see SOMETHIHNG.

josh greene

well I didnt know that the O2 sensor wire was sheilded and I just cut it spliced it and put the wire for the AFR there... maybe thats the problem.

coldfire

iTrader: (1)

lol, bingo!

but first go test the sensor like HAILERS mentioned. if that's working fine, then properly wire that thing up. actually you should properly wire it up regardless!
but depends where you splice it from...

HAILERS: how far does the shielded wire extend to? all the way to the ECU?

- Aaron

josh greene

What are the effects of leaving the O2 sensor disconnected??? the wire comming off the o2 sensor is exposed and is cut part way through. I think its time for a new one.

HAILERS

No problem disconnecting it. It will cause the gas milage to go up a hair or two ....til you buy another. Have fun getting the old one out.

Question: do you have a digital meter? If so there's something you can do to check the 02 sensor out. It's mentioned in one of the first posts on this thread.