MS3X - VVT back feeding ecu on key off?

[suberimakuri]

Hi everyone,

Have a Toyota 4age 20v with vvt.
MS3 board with MS3X expansion.

12v switched and fused to VVT solenoid.
Other side connected to VVT input on MS3X.
Have 12v connection to MS3X diode as per docs. (Photo in manual is my ECU).

When turn key off with VVT fuse in, engine keeps running albeit sluggishly.
When pull vvt fuse, engine stops.
VVT works according to table settings. 0 up to 2000rpm, 100 from 2-6000rpm, 0 from 6000rpm plus.
Vvt solenoid resistance matches a spare solenoid.
Spare solenoid does same thing.

Just had a brain wave that maybe I need to switch wires at solenoid but didn't think had polarity.

I could use a relay instead of directly controlling it.

Any ideas?

PS, sorry posting from phone but will upload msq tonight. Cheers.

[billr]

"12v switched and fused to VVT solenoid. "

"Switched" from what? Apparently, not the ignition switch or anything controlled by it (like FP/injector relay).

[suberimakuri]

Pretty sure it's switched by fuel pump, along with coils injectors, etc.
However maybe I've made a mistake with this!

[ragepower]

Pretty sure it's switched by fuel pump, along with coils injectors, etc.
However maybe I've made a mistake with this!

On my project (bmw v8 with dual vanos), I had 2 similar problems:
1 - The idle valve was supply by 12V bat. And the engine did not stop. I switched for 12 switched. And It solve the problem.
2 - The engine did not stop. The problem was to much current supplied by the fuel relay and besides the ignition key was turn off, the relay wouldn't "deactivate". To solve it was applied another relay, controlled by the fuel relay. So the current was slitted and the engine will turn off.

[suberimakuri]

Thank you.
I need to confirm #1 is actually fp switched still
#2 maybe. Factory vvt uses a relay so may do this.

[suberimakuri]

Reviving my old thread.

Individual fuses between relays and coils/ pump/ vvt..

Start:
1. Key switched ignition to relay 86, 85 to earth, 87 other relay 86s and ms3x, 30 bat.
2. FP and injectors relay - #1 power to 86, 85 to ms3x fuel pump, 87 injectors and fuel pump, 30 bat.
3. Ignition coils and VVT relay - #1 power to 86, 85 to ms3x fuel pump, 87 coils and vvt, 30 bat..
4. Fan relay - #1 power to 86, 85 to ms3x fan output, 87 to fan, 30 bat.

I tried giving ms3x ignition key switched power directly and put all relays on ms3x fuel pump. No change.
Wondering if too many relays for ms3x I changed.

Finish:
1. Key switched ignition to ms3x and 86, 85 to ms3x fuel pump, 87 other relay 86s, 30 bat.
2. FP and injectors relay - #1 power to 86, 85 to ground, 87 injectors and fuel pump, 30 bat.
3. Ignition coils and VVT relay - #1 power to 86, 85 to ground, 87 coils and vvt, 30 bat..
4. Fan relay - #1 power to 86, 85 to ms3x fan output....

With this change where ms3x only earths one main relay (#1) the other relays 86 definitely switch off with key when engine not running. Even with vvt fuse in.

But... when vvt fuse in the engine still runs (poorly) when switch key off. If pull fuse then engine cuts out with key perfectly.

What am I missing.... please help

[suberimakuri]

Okay might be solved.
Put ms on own relay ignition switched.
This relay has no other outputs connected.

Final working:
1. MS relay - Key switched ignition to 86, 85 to ground, 87 to ms3x, 30 bat.
2. FP and injectors relay - key switched ignition to 86, 85 to ms3x fuel pump, 87 injectors and fuel pump, 30 bat.
3. Ignition coils and VVT relay - key switched ignition to 86, 85 to ms3x fuel pump, 87 coils and vvt, 30 bat..
4. Fan relay - key switched ignition to 86, 85 to ms3x fan output....

[rickb794]

An idle valve, a fan relay, boost control solenoid, fuel pump relay basically anything else driven by the MS must have switched power.
When the MS power is off it is in an undetermined state and there may be unexpected behavior if controlled devices are still powered.
That is a big safety issue.

Sometimes a diode is needed on an alternator exciter/regulator so it does not feed back.