Motec tuning

[Andrew Theurer]

On Monday 01 October 2001 11:35 pm, you wrote:
> I have not been able to find any significant difference between high
> and low impedance injectors or between resistor vs. no resistor.
> The Motec will run any combination quite happily so if you're
> concerned about cutting the harness up just set the injector current
> value to 0.  If you use a high value the box will flag an "injector
> peak current not reached" error.

Thanks, this is good news.  

> You can do a little experimenting yourself as the Motec box has
> diagnostics that will let you fire the injectors and ignition circuits.
> On the injector test you can fire each one individually and vary
> RPM, PW and firing current.  By varying your battery voltage you
> can generate your injector dead time comp table.

Now, doesn't motec have preset calibrations for injector dead time for 
specific fuel injector models?  Would the inline resistor affect this?  

> I zip tied the injectors to the rail and let them flow into their
> own containers.  If by chance you have any variations in flow you
> can use the Motecs individual cylinder corrections to even things
> up to start with.

Hopefully this will not be a problem.  These injectors came from RC 
engineering (bosch 1000cc) and were balanced within I believe 0.2%.  

> Later on you can do individual cylinders on the
> dyno via EGT/AF/plug reading etc.  Before you install the turbo
> header, TIG on some 1/8 NPT bungs or weld Swagelok 1/4"
> fittings straight on.  That will let you pick up exhaust pressure,
> EGT or AF ratio.
>
> Your car should be bike killer when it's all done.  Hopefully it will
> put down more than a local here with a very sad HKS twin'd
> Supra making only 619rwhp.

Only 619? haha.  Another local Supra is at about 600 on pump gas at roughly 
18 psi.  At 28-30 psi, these turbos are good for 700 - 800 rwhp depending on 
your A/R.  Mine are slightly different than most I have seen (2835R) with I 
believe a slightly larger compressor wheel, so we will see.   Anyway, walking 
'busas on the highway is getting kind of old in my town :)

-Andrew

>
> ---- Original Message ----
> Date: Mon, 1 Oct 2001 10:26:37 -0500
> From: Andrew Theurer <habanero at us.ibm.com>
> Subject: Re: Motec tuning
>
> Mine is not quite ready to fire yet.  I need to hook up a few more sensors.
> It sounds like I am doing the same as you are, using the stock harness.  I
> have a harness "extension" from Field of Japan, which is normally used to
> plug between the stock harness and the stock ECU, allowing you to tap for
> whatever reason without cutting the stock harness.  I am using it to serve
> as
> an adapter from the stock connector to the Motec connector.  I have not
> really spliced my stock harness at all.  I have re-terminated some ends of
> the harness for different style sensors.  For example, my stock MAP sensor
> is
> only a 2 bar, so I am using a delco 3 bar, which requires a different
> connector.  Same for Baro (using wires from second TPS), and air temp
> (probably using wires from EGR temp).  Injectors also were re-terminated
> with
> connectors from MSD to fit Bosch top-feed injectors.  Stock crank, cam,
> throttle, and water temp sensors are used.  Only new sensors are baro, map,
> and air temp.
>
> I am using the M48Pro with ignition expander and the bosch wideband option.
>
> One problem I am facing is injectors.  The stock harness has a "SFI
> resistor"
> inline with all the injectors.  I think Toyota did this to reduce the types
> of injector drivers they needed for all their cars.  The Supra turbo comes
> stock with low impedance injectors, while the non turbo has high impedance
> injectors.  The turbo model has the resistor, while the non turbo does not.
> They both measure 13.8 Ohms across the circuit.  I know my bosch injectors
> are 2.5 ohm, and I can obviously find out what they are with the resistor.
> My problem is, do I find out that resistance and tell the motec, leaving
> the resistor in place, or do I just hack the harness, remove the resistor,
> and tell motec 2.5 ohm.   I'd prefer to leave the harness alone.   I am
> worried that if I give a high impedance number to the motec, it will assume
> different
> properties about that injector vs a low impedance injector.
>
> Thanks for the help,
>
> Andrew
>
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