Point of AFM idle screw?

[JustCallMeOrlando]

I would hesitate to adjust the AFM idle screw at all unless you think someone has done it beforehand.

[o_man_ra23]

I thought about that too camrygt?. The thing I noticed though was that the AFM sending out a definite signal at idle, so it must be opening enough for the ECU to register something. Ah well, perhaps Toyota just weren't so confident in the ability of their ECU's to do it at the time

Mate, your definite signal has a finite resolution... you can measure it to within very fine limits with a good multimeter, but if your ecu just has an 8 bit analogue input, then you will only have a total of 256 registered points between fully open and fully closed. This can be helped a bit with a non-linear varistor, but then that takes away from the fine throttle control you can acheive at the high RPM that these motors are designed for. SO.. at idle, a 1 bit change in the analogue input can be 20 or more percent change in overall reading, which will make a drastic difference, then at high RPM that same 1 bit change can be less than half a percent change... so your idle suffers from lack of resolution, hence the need to fine tune it, they get it to within a bit of where it needs to be, and then smacks it bang on that bit with the adjuster screw. With the newer cars came better microprocessors and higher resolution analogue inputs, and better non-linear varistors... so now there might be a 16 bit analogue input... doesnt sound like that much of a change, but it works out to be 16 thousand bits between fully closed and fully open... much finer resolution. think about the 256 colour screen your computer once had, and this difference it made going to a 16 bit screen with the 16odd thousand colours, and now you have your 32 bit screen with several million colours. That is why the early efis needed the manual adjustability that the new cars dont.

Cheers, Owen

[JustCallMeOrlando]

Fair enough, I figured this may be the case. Electronics have come a long way, this I realise. The Gen3 ECU is so uber complicated compared to the 1GEU ECU which was simple as. Cheers.

[willwal98]

JustCallMeFrank -- If you look next to the idle screw, on a little flat section just below it, there is two numbers. They will be REALLY faint though, because they didn't stamp them that hard. I had to get some cleaner and give it a little scrub to be able to see them. Mine had 66, I set mine as close to 16.6mm and its behaved markedly better as a result.

As for the DFA, I'm still dubious whether or not it can be used.

I just checked mine with the veries and I was less than 1/4 of a turn out. I set it by ear last time.

[o_man_ra23]

wanna trade ears will??

Cheers, Owen

[JustCallMeOrlando]

Methinks I've got some investigation to go, i've done something that means that 66 on my AFM doesn't mean a lot any more