Gday

I have had this on going problem with my car for about 2 years and im sick of it. My car hunts around and has nothing until about 2500rpm(a massive flatspot). I had it at my tuners last Friday and he couldn't work it out. We had the car on the dyno to see what was going on and we found that the oxy sensor was going crazy (3rd oxy sensor).
Apparently when cruising the sensor reading is suppose to lean out/run rich spiking up and down real quick and it will work it self out. The sensor is doing that very slowly and this is why there is that big flat spot (It leans out so much it just coffs and spits, untill i put my foot nearly flat to the floor).
When I WOT its fine, it bypass's the oxy reading. Does anyone know what could be causing this problem?

Last edited by GeZza200 on Mon Jul 19, 2010 12:04 am, edited 1 time in total.

I would try another ECU..... I guess you have been right over everything... right????

yep been over everything, have tried 2 other ECU's aswell, im thinking something has shorted somewhere

there is a grey earth wire that bolts onto the block near the dizzy, ensure it hasnt broken off,
Alternatively test with a multimeter the resistance between pin 49 of the ECU connector (with ECU unplugged) to the engine block, on ohms range and it should be 0.0 or very close to it.

Id check the MAP sensor. A failed MAP sensor will make the engine run rich causing the oxygen sensor to foul up, causing it to repeatably fail.

yeah we tried another MAP sensor and it didn't help