2JZGE Key on, engine off SYNC issue

[iWrench]

I've have installed my MS3pro in my 2001 IS300 with a newly turbo'd 2JZ-GE. The MS3pro is installed in parallel with the factory PCM. Everything is running well when the engine is running and I'm getting the tune worked out. I've been able to daily drive my car with no major issues for over a month.

The problem is turning the key to the 'on' position with the engine still off my sync counter begins counting off, the tach needle begins bouncing up and down to about 2k rpm, and the injectors will begin firing. The factory PCM also sets a DTC for the cam position sensor. My work around for this so far has been to simply always start the engine right away when I turn the key on. The engine starts and runs normally and I've never noticed a loss of sync while running. I've obviously run both the cam and crank VR signals to both the MS3pro and the PCM. If this was going to be a problem I would expect it to be a problem while running but so far not at all. My guess is I have a setting wrong somewhere. It could be some sort of interference but why only with the engine off?

Any ideas? Things to check? Maybe a better way to do this? Anything is appreciated.

Thanks!

[AbatelliCristian]

max9926 is adaptative. When the engine is off the level is low.
You can try use resistor 4,7k between vr+ and vr-. If at the high rpm you have lostsync increase the value.

[iWrench]

Thanks for the reply.

Just so I have it straight. Max9926 is the VR interface circuit inside the MS3pro, right? I've got 3.3k, 4.7k and 10k resistors on hand. I will experiment with those and report back. As far as placement goes, since I have a factory PCM in parallel, I'm assuming I need to make sure these are only between the MS3pro vr+ and vr- wires?

[AbatelliCristian]

pcm is in parallel. If you insert resistor is for ms and pcm... try with 4,7k

[nathaninwa]

What is the reason for still running the stock Ecu?

[iWrench]

I'll start with the 4.7k resistor then and scope the signals to see what I'm getting for a pattern.

The factory PCM is still in there for 2 main reasons one is to pass local emissions (they plug into the OBD port). The other is to run the electronic throttle body. Also, it's a auto transmission car but I don't know exactly how involved the PCM is with the TCM on the IS300's. The PCM is also currently running things like the fuel pump and cooling fan, but it's a work in progress. I may give control of those sorts of things to the MS later.

[iWrench]

I tried a 4.7k resistor between the vr+ and vr- wires with no change. I also went ahead and tried the 3.3k resistor as well. The issue is still present Key on, Engine off. Also, I didn't notice any difference in the noise I'm seeing on the cam position circuit. There are occasional voltage spikes from 0.5 to about 1.5 volts which appear to coincide with the random injector pulses I'm seeing. I assume the MS sees these spikes as a trigger for the injectors?

Interestingly, I can work around the whole issue by fully depressing the accelerator pedal to 100% and then turning key on. After about 20 seconds, I can release the pedal and no issue so far. I'm wondering if I'm tracking down some sort of interference from some other component. But, I've rechecked my grounds and the MS3-pro is on it's own circuit controlled with it's own relay. The only other thing I added at the same time is the Innovate wide band AFR again on it's own circuit and relay.

Kind of lost here.

[AbatelliCristian]

if the problem is in the cam sensor, insert resistor in the cam sensor. Normaly for 1 tooth in the cam, I use 1k resistor

[iWrench]

That was what I was thinking about trying. I went and bought 1k resistors. I'll give it a try.

[nathaninwa]

Both my crank and cam sensors on my 2j took a 10k inline with vr+ and a 1k shunted to have a clean signal

[iWrench]

Dang. Okay, I guess I can wire in the 1k resistor as a shunt for both VR sensors first. But, you're saying, if that doesn't work add a 10k resistor on the positive side of both cam and crank sensors? I want this all wired before both signals are split to each computer, right?

[nathaninwa]

Wired straight to the Pro I would get cranking rpm spikes to over 7000, which would command like 35* of timing, the motor would stall, then fire up, only after resetting and taking the cranking 92ish kpa as the current map and run all goofy


I'd wire your setup after the split if at all possible as I bet the stock board already has its own buffering built in

[iWrench]

I'd wire your setup after the split if at all possible as I bet the stock board already has its own buffering built in

That was my thought originally (I mean it worked before the install) but it sounded like Abatelli's last post suggested I shunt the circuit at the sensor. Anyway, thanks for clarifying, makes sense.

This has been the only real issue I've had with the MS install on my 2J. I was prepared for all sorts of horrible. However, after I get this ironed out I'll be wiring up the igniter to the MS. So, my day might be coming. I planned on doing this in stages as this is my first time installing and tuning a full stand alone system (only piggy back systems previously). I'm barely running any boost (a whole 4psi). New injectors are going in soon so I can start increasing boost.

[AlexBerry10295]

Gday!
Sorry to be rude and chime in, im just interested in your is300 build and the information youre providing upon it. As im delving into the exact same project, NA-T and microsquirt.
Did you end up resolving this issue? Just out of curiosity?