I think my car is running too cold. Suggestions? Might be the O2 sensor, help?

[TERRA Operative]

Well, I nailed the problem. The O2 sensor wasn't heating up enough.

I went through a few tanks of fuel (at 250km per 50 litres...) to see if it would come good. When it was evident it wasn't, I hooked up my Jaycar O2 meter kit and noticed that it was reading off-the-scale lean all the time (hence the ECU was pumping in fuel to try to correct), but when I gave it a thrash, it came good with the hot exhaust gasses heating the sensor enough to work until I slowed down and it read lean again.

I disconnected the wire from the heater that goes to the ECU (the ECU grounds the heater to turn it on, the other side goes to the EFI relay or whatever) and hooked it straight to the chassis so the heater was always on.
I took it for a drive, and bingo. The O2 sensor was reading at a solid centre of the scale, and was maintaining a good consistent reading.

Now to make the mod semi permanent (depinning the connector at the sensor and wedging the pin under a bolt head isn't best practice... ) and decide if I'll open the ECU to trace any possible fault or just leave it bypassed.



Could also be a good excuse to ceramic coat the headers to help keep the heat in all the way to the sensor (and keep the heat away from my oil filter and cooler lines).

[dnegative]

Never would of thought a O2 sensor would of made such a difference, I was under the impression the lambada input had limited sway on the fuel mapping.


But, defiantly go for the ceramic coating, its well worth the cost of admission.

[TERRA Operative]

Yeah it's crazy, I just hope there's nothing else at play, I am still to see how the economy improves when I fill up next. I have a fuel usage logging app on my phone so I can see exactly what it's doing, the last two tanks were at about 13.5l/100km....

A mate got his headers ceramic coated when we installed them on his Levin (HKS 4-1 headers like mine) and they do look like total sex, worth it for that alone I reckon.
I gotta do the coilovers first, but after that it might get done, pending other things that come up.