running rich, odd o2 readings.

[chrisfullwood]

I have a 90 gsx, with vr4 engine, 91 eclipse gsx ecu (mods list is in my profile). starting the car, the idle is high, the o2 voltage starts to rise as it should, but will get to about .55 - .70 then start to sink down to about 0.06 - 0.07 and it will stay there running super rich.

ive checked the wiring as best i can. and i cant find why it is doing this.

thanks
Chris

 

[FORMONTOYA]

The sensor is more than likely taking a dump. When they start to go bad they'll read low.....when they've taken a full dump, they'll read 0.

Of course with the low reading the ECU will add fuel to try and bring it back in line, but can never make it before the low fuel trim is maxed out.

 

[chrisfullwood]

thanks for taking the time to read my post.

its a brand new o2 sensor?

is there anything else that could cause the sensor to act that way?

 

[FORMONTOYA]

The other thing it could be is an exhaust leak pre O2....that might explain why it starts to rise, then reach a point where it falls. A small crack/leak when cold would grow once heated.

I had a leak between the turbo and O2 housing on mine (non-gasket connection), and it just never pulled off about 0.04-0.06.

Get the motor up to temp or where the O2 readings are at their lowest, and a can of Seafoam ($8 at AutoZone/Pep Boys) after the heat shield is removed will help pinpoint a possible leak in the exhaust.

Just be forewarned, the neighbors will think your house is on fire.

This is what you would be looking for. It just sucks up through the BOV line.
http://www.seafoamsales.com/motorTuneUpTech.htm

A little long, but worth a read.....
http://dsmtuners.com/forums/showthread.php?t=222686&highlight=seafoam

 

[chrisfullwood]

i just drove the car, the o2 reading will jump from normal to 0.00, the afr gauge freaks out.

you can tell the car is changing the fuel level, when its getting the signal from the o2 sensor, when its not working, it jumps to 20.00 on the air fuel ration meter. (20 is the max for it im guessing)
at idle, the car is just dumping fuel into the engine, it smokes soooo bad. and its pure fuel

ive checked all the wires, the connector was partly broken on the o2 sensor, but ive got it pretty well fixed. but even with the o2 sensor unplugged, it still shouldnt be running this rich.
it has a 2g mas, 550cc injectors, rewired pump. ngk plugs and wires.
what else could be making the car run this rich. the timing is around 5-7 degrees btdc,. it does have a sporadic miss at idle aswell.

odly enough the car boosts well, runs great, but it just runs rich. ridiculously rich at idle.