Battery Problems ???

[R31Heaven]

Just intersted in the what effect do crook batterys have on EFI cars do they make them run like crap due to not gettng enough spark? what symptons would this cause in a RB20DET as my car has been running off, and the other day my battery went flat after having the radio on for 1hour. Would they cause you motor to run crappy in cold weather? I am grasping at straws to work out why my car is missing while idleing. I have changed ECU temp sensor O2 sensor, the only thing I havn't changed it the AFM

[S14Drift!]

When your car run everything should be OK, cause the Alternator generate enough current...

For your idle problem & missing, I would suggest re-grounding the engine, MAF and battery ... (with non permanent wire at first, then see if it make a difference, if so install those GND.

To verify if you really need GND, take a multi-meter, and measure voltage between frame GND, and engine, then MAF, then battery, and see if you read any offset! (check in DC mode, then check in AC, AC will give you the noise measurement, and DC only offset)

[R31Heaven]

To add to my first post, when my car is running & I turn on the heater fan the engine revs die down ???