Hi all,
I have once again got the dreaded engine idling issue on the V8, and there are only three items that I have not as yet replaced (as far as I can think), these being the Gearbox speed sensor, the ECU and the O2 sensors.
When I bought the mighty 4.6 V8 1997 plus 8 seven years ago I fought with the idling issue for some time, ie stalling at lights, and erratic idling in general. I gradually changed all the parts, but no one thing seemed to resolve it. However after replacing most the related parts the problem went away!
I thought I had cured the problem by fitting a new air idle valve, new Airflow meter, new throttle position sensor, Tornado chip, Bosch injectors, new coil and RPI spark improvement device. I even fitted a new fuel pump, and ignition trigger in the dizzy!. In addition to resolving a number of vacuum leaks.
These mods seemed to solve the issue with only the occassional rare poor idle speed which I learned to live with.
But now the problem has returned, in that the idle speed after start up (only when the car is moving) remains very high until the car is at standstill, in which case it drops to the correct idle. After about three or four stops at traffic lights the idle speed then performs correctly for the rest of the journey.
However if I stop the engine the problem then resums untill I have stopped at three or four traffic lights. Very annoying.
It seems like the ECU learns to reset the idle somehow?
I have fitted another new Air Idler valve, (no improvement) and I can only think the problem may be the gearbox speed sensor or the ECU or the O2 sensors.
I am going to fit one new O2 sensor soon, as I can see that the even bank exhaust pipe is black with soot and the odd bank is perfectly clean, so I assume one of the O2 meters is playing up, giving the even bank a richer mix, and this may indeed be the cause of the erratic idle, who knows?
Has anyone figured out where the R380 gearbox speed sensor is, as I would like to check it out. I think it is an electronic type sensor as (if my memory serves me right) saw some wires coming out of the off side of the gearbox, which I assume is the electronic speed sensor.
I have also noticed that sometimes I get strange and erratic readings on the odometer, which I think possibly takes a signal from the gearbox speed sensor.
Anyone know anything about this electronic speed sensor, I assume it is a pulse device similar to a modern ABS sensor? Any help would be great.
I can only find info on the mechnical type gearbox sender, but I dont think this is the same device.
Just thoght I would ask the Forum guru before I get the car on jacks and start poking around!!
