Holden vt v6 auto piggy back to stock ecu

[VT1GER]

Hey guys,

I have a holden vt v6 auto which has the standard ecu in it with VATS disabled. For remote start purposes.

I just got my new stroker engine in and i have a Autronic SM4 ECU wired into the car but im having a few issues with the wiring side of things. Mainly the ignition side of it.

At the DFI module there is 3x 18x and tacho (1x?) inputs and outputs. But i have 5volt + supplied to the Bypass wire, So i belive the dfi controls spark etc under 1200rpm with the 18x wire. then over that the ecu takes over and controls it all with the 3x wire. So i think i am needing to use the 3x sensor IN to the cylinder + of the sm4.

Just not 100% on how it all works from the factory ecu/DFI. any help on how to wire it up would be greatly appreciated. I have a few other small questions on the install to relating to the car being an automatic and the transmission needing to use some of the same sensors as the ecu.

[kojab]

What benefit do you see in using the SM4 Autronic ECU as a piggyback over using your existing factory VT V6 PCM to control your new stroker engine with factory auto?

[krusty]

Yeah have to say Vtiger, wrong tree been barked up

I suspect a troll thread but meh

[VT1GER]

i was told my engine build depended on what ecu it was going to be run off. So i opted for the SM4 as that is what the tuner is most familiar with.


The only "piggy back" part of the install is shared sensors for Coolant temp, Throttle position sensor, Intake Air temp (as this is what the auto needs to read) but im just having issues with the ignition side of it, with the module in bypass mode all spark.timing etc is all ecu contolled which is all off the sm4. So its 95% a stand alone ecu install.

Just after some info if anyone has played around with the stock ignition module.

[immortality]

Well I'm going to say drop the piggy-back and just use the factory PCM as it's more than capable of doing the job. It's what this whole forum is basically about

[VT1GER]

is there any reason my builder would suggest changing the ecu? is there any limitations to it tuning wize?

basic layout of the engine is - forged bottom end, custom grind clive cam, 4.2l stroker, ls1 valves adjustable shaft roller rockers, port matched inlet manifold etc. Would i see any loss of power without the sm4?

[krusty]

SM4 is his way of getting your money in his pocket. This most likely is not what's best for the car, you or the build imo. See this all the time.

At risk of being wrong, what's the specs of the build that make it need an SM4?

[VT1GER]

Basic specs posted above. The ecu I sourced myself and fitted myself. The builder is also not the one tuning it. So no money to gain on his part. He just strongly recommend it. I didn't know better as I didn't think the stock ecu had much room for tuning

[antus]

I agree stock pcm would be a better way to go. We've made them more accessible to people doing it themselves since 2009 A lot of tuners who dont have time to research on the net or dont do holdens enough may not know whats available. Those that do would be better suited to help you with the tuning.

I'd suggest for no boost you check out the realtime bins thread here: http://pcmhacking.net/forums/viewtopic.php?f=27&t=613 or if you plan for boost the1s enhanced bins here: http://pcmhacking.net/forums/viewtopic.php?f=27&t=2518

You could grab the suitable bin, xdf, and adx (packaged seperately for realtime bins therad, or in the one zip on the1s thread) and get tunerpro rt from tunerpro.net and have a play to test suitability before you go any further. You certainly can make it run your engine just fine, and you will get the best levels of integration with the car since everything it expects will be connected.

For the SM4, I suggest you email autronic. They should be able to supply wiring and settings to your car. Post details up here if you can to help others in the future who land on this thread from google.

The bypass signal is a toggle and the factory pcm is programmed when to take over start timing at crank time from the module. Its about 400 rpm. It sounds like by hard wiring it your setting it up so the SM4 will run spark from the moment you key on. EST is the spark output from the pcm. The tacho is an output to your dash and that'll stay the same regardless of your pcm. 18x and 3x depends on what the SM4 wants.

You'll definately get a check engine light going this way, and it would be ideal to tune the factory pcm what to expect so it can raise a CEL when it sees real problems like engine over temp. But at that point you might as well tune it for spark and fuel too, and the transmission to firm up the shifts a bit (assuming the trans condition is good).

[VT1GER]

Hmm. didnt realise they had the ability to do live tuning with the factory ecu these days. It does make sense if its all going to function 100% and do what i need it to i may as well stay with the factory setup. Price i sell the sm4 will pay for the tune too. Thanks for the info guys, il look into playing around with it abit myself and see how it goes. Obviously there is some form of hardware that is needed to connect to the ecu to talk to it. Time to start hunting around these forums a bit more for info.