Configuration Resistors on 3VZ-FE ECU

[Fizzy]

A quick query - even though the resistor switches the maps from auto to manual on the main cpu, is there a possibility that the auto processor is interfeering with the other's operation? I mean, I assume that the auto cpu is still getting power, signals etc, so when it's expecting to reduce timing advance etc the other cpu is advancing it back? This obvious wouldn't be an issue on the proper manual ecu as the auto processor isn't there....

.....is there an easy way to properly disable the auto cpu? Remove one or two of the resistors or bridge components that give it power?

If I had a spare auto ecu I guess I could find out by changing the mode resistor and removing the auto cpu, and then take it for a RR again and see how it compared to my previous graph.

[stevehall]

I've had the auto->manual resistor swap for almost a year now with little trouble. Standard '92 engine, fully rebuilt, compression up from 9.2 to 9.8:1. It does have trouble starting sometimes where it will fire up, and then the revs will die off and stall, but always maintains propper idle on the second attempt, no idea what that's all about.
Dyno resutls from the other day:


Just wondering if there is any more power available from stock parts, is the 200hp engines from '94- entirely down to the ECU? I'm just thinking, I have access to an iPhone with an accelerometer based dyno program. It might be worth doing a number of runs in different ECU configurations to see the different power curves.

[aussiemr2]

By the end of this year I should be able to shed a little light on this as I have a 93 engine fully rebuilt but with new 94+ valve springs in the heads which have a lower compression force
Also using Mahle pistons which are 20 grammes lighter per piston than the stock Aisin ones
My compression ratio should be quite good as I have had a light skim on heads and block and using Ferriday gaskets which are a bit thinner than standard

Really keen to see what differences the ECU will make to all this, still looking out for a late model ECU, harder than you might think even in Australia

[jon.sole]

A quick query - even though the resistor switches the maps from auto to manual on the main cpu, is there a possibility that the auto processor is interfeering with the other's operation? I mean, I assume that the auto cpu is still getting power, signals etc, so when it's expecting to reduce timing advance etc the other cpu is advancing it back? This obvious wouldn't be an issue on the proper manual ecu as the auto processor isn't there....

When the resistor is in the R751 position various sections of S/W in the processor are skipped over, I believe these bits of code are used to communicate with the A/T controller processor. The R751/R752 resistors don't change which basic maps are used, but in M/T mode because the S/W doesn't communicate with the A/T controller processor it ignores the ignition retard signal.

.....is there an easy way to properly disable the auto cpu? Remove one or two of the resistors or bridge components that give it power?

You could try removing the crystal oscillator for the A/T controller. Without the crystal the A/T controller won't run at all. I've highlighted the crystal on this photo:

If I had a spare auto ecu I guess I could find out by changing the mode resistor and removing the auto cpu, and then take it for a RR again and see how it compared to my previous graph.

You could always de-solder the A/T controller and solder a socket in it's place. I've had the main processor in a socket for the last year or so without any problems.

[Fizzy]

Thanks for the info Jon. I may have a tinker now that the I have the van as a backup (just in case ;) ).

Steve's RR plots look fine though after he's done the mod - so may just be RR issues on the day for my wierd plots, and my slight hesitancy issues down to the fact the engine has done around 230K miles now so may just be wear and tare...

[Bev]

I've just been having a look at my 93 JDM camry ECU, and it's different again. I'm starting to think that perhaps it's a NZ market ECU.

ECU P/N: 89661-33180

Fuel/IGN CPU P/N: D151803-0680
S/W: 5A41A-2-8806

A/T CPU P/N: D151802-8830
S/W: 7463-0403

Knock CPU P/N: D151802-8860
S/W: 572 187N

Standard resistor configuration: R753, R752, R755

Spots with NO resistors: R751, R 754, R756

This fits in with the A/T or M/T configuration resistor. However, it would appear that my map configuration resistor is in what you thought might be the "safe" map configuration spot.

Odd.

Bevan

[Bev]

According to this, there are a shite load of different ECU part numbers...
http://www.toyotanation.com/forum/ar.../t-374547.html

I've moved my R751/R752 resistor to the R751 position. I wonder if I should move it back?!

In the long run I'm going to wire in my megasquirt anyway.

Bev

[ColleyV8]

Is this still a way to bypass the iscv problem or should I still do the POCVIP thing

Regards

[bigcw]

Guys

What's the general consensus with these mods now they've been around for a year or so? Is it considered a good thing to do to put the ECU in 'manual' mode? Do the alternate maps give any better power?

Not sure if it helps, but I'm owed a favour by the local rolling road guys. If I wired up some switches to the ECU I could probably persuade them to run the car up for me with the ECU in the various switch positions. Four runs (working on the auto/manual and map resistors) would likely be ok, if I asked for 8 runs (to try all combinations of the three resistors) they might not be so keen, but I can ask.

The only 'issue' would be that they're not going to be happy if I wanted to drive the car between the runs for it to re-learn as that'll take a whole load more time as we'll have to keep strapping the car down. Would have to be run... engine off... flick switch... start up... run again. Anyone shed some light on what exactly the ECU learns, if it survives a restart of the engine (I'd assume so) and if values it learns with the resistors in one set of positions are valid for the others?

Is this likely to be helpful to the cause or am I wasting my favour? :)

Cheers, Chris

[stevehall]

I've had my ecu in 'manual' mode since I installed the engine (date earlier in the thread). I've only had one problem with the running of the engine, evey time it starts up cold, it never opens the IACV, you can keep it running if you open the throttle slightly, but close it and it stalls, fire it up the 2nd time and it will work completely normally that time, with no troubles. So not sure if anything was cured, but I've never had the stalling problem that others have once the car is running, just on startup.
Need to get the valve pocvipsed.