bluegoose

Hello all,
I have a 89 firebird, with accel gen vii. I also have a air/fuel ratio gague mounted inside of car. I decided to replace the 4 wire 02 sensor because it has about 45K miles on it. Anyway I replaced the 02 sensor with an Accel Sensor (part number 77761). Now when the car is hot, the air/fuel gague is reading very lean!! I had the Accel kit installed about 2 years ago, and the old 02 sensor was an accel part. When the old 02 sensor was installed, the gague would go rich when I punched it, now it just barely moves out of lean



What would cause the gague to read very lean???

Any information on why this would happen would be greatly appreciated.

Thanks in Advance

Brad

bluegoose

update:
I replaced the 02 Sensor with the old one and my gague is working properly.. guess I just have a bad 02 sensor, unless I need to do something to CALMAP when I replace the sensor...any comments..for the calmap guru's..

aDFIguy

Does your main screen in CalMap read actual A/F ratio, or HEGO voltage?

P/N 77761 is for a HEGO sensor -- 4 wires connected to the sensor. Make sure that you are not trying to use that sensor with a wideband controller -- it would have 7 wires going to the sensor and may also have a gray connector which would go to an A/F gauge.

If you need the 7-wire sensor, it's P/N 77065, and they are $$$.

FYI, if you do need the pricey replacement sensor, look into P/N 77062 instead. It's a replacement O2 controller based on the Bosch sensor with the added bonus of having an integrated data logger for your Gen 7 ECM. You can probably buy that complete system for what you would pay for a 77065 sensor. As long as you're not making too much boost, and the car is already tuned, the cheaper sensor would probably work just fine for you.

Sorry - re-read your post and saw you originally had a 4-wire sensor. Sounds like you got a bad sensor. What are you using to read your Air to Fuel ratio with if you have a HEGO sensor connected to the Gen 7?

bluegoose

I am going to order a new 02 sensor, in fact the orginal one doesnt look like the new one, but they both have 4 wires and the same connector.

I have a Auto Meter Air/Fuel Ratio gague.

More comments...

Thanks

aDFIguy

Use CalMap to record Engine Speed, HEGO voltage, O2 Feedback %, ECT, and Injector Pulse Width values during a warm start and for a couple of minutes afterward. Do this with each sensor and you'll be able to tell if your new one is responding similar or differently from your old one.

For a fair comparison, the ECT values must be very close to eachother for each recording session. Make sure the car is fully warmed up.

The HEGO voltage values will represent A/F Ratio. These numbers should start off at about 0.9 volts right after the engine starts, drop slowly from there, and settle into a somewhat constant range of values after a couple of minutes. Look at any difference in the numbers between the 2 sensors.

Look at the injector pulse width values to see if the engine is being fueled any differently. If the pulse width values are not different, then the problem may be between the new sensor and your A/F gauge. Maybe make a chart of HEGO voltage vs. your A/F gauge reading for each sensor.

Maybe the new sensor has a slightly different breakpoint between a rich reading and a lean reading -- and that value doesn't line up with the one used by your gauge? 1/10th of a volt can mean a lot when you are dealing with a HEGO sensor. They only read in a range from about 0.1 to 0.9 volts.

bluegoose

DFI Guy,
Great info, I will do some data logging this weekend.

Anyways I need to know if this is what I need to log..

Couldnt find: what about using this:
HEGO Voltage EXT. HEGO V
Injector Pulse Width PW ms


Also found these in which I could log but need some explanation on difference:

HEGO A:F A:F
HEGO / 02 A:F
Target A:F
02 Voltage

I had the Accel Gen VII installed about 2 1/2 years ago and would really like to attend a class on how to tune using calmap, everytime I take car to shop to dyno tune it cost me about 500 bones and then I cant find anything they really changed in CALMAP.

aDFIguy

Injector Pulse Width PW ms => Use this to monitor your actual fueling via Injector Pulse Width in milliseconds.

HEGO A:F A:F => Monitors estimated A/F when using HEGO sensor in a special HEGO A/F mode.
HEGO / 02 A:F => Monitors either HEGO voltage or UEGO A/F ratio depending on type of O2 sensor selected in the ECM.

Target A:F => Use this to monitor your current targeted A/F ratio.
02 Voltage => Use this to monitor your raw O2 sensor voltage.

bluegoose

DFI I just PM you