Low-Imp. Injectors on MS3X?

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Re: Low-Imp. Injectors on MS3X?

Postby racingmini_mtl » Fri Apr 15, 2011 5:27 pm

Peter Florance wrote:I did some quick testing with Low Z injector and 3.3 ohm resistor, using the accelerometer pcb that I brought to 2008 megameeting
At lower voltages, there's a big difference in opening times with and without resistor. At 13.2 volts it was difficult to see any difference. That may explain my customers cold starting issues if battery is not fully topped off.
Perhaps I will be able fix with battery correction voltage...

Note this tester does not yield actual dead time measurements but I thought it would be useful as a relative test.

I'll probably be stating the obvious here but if there isn't enough voltage for a reliable or consistent opening of the injectors, no amount of battery voltage correction will help. That is the advantage of the peak&hold driver which will always give the maximum voltage available from the battery for opening the injectors. And the advantage of the LM1949 current sensing circuit over the PWM fixed time period is that the peak is always only as long as it needs to be.

Jean
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Re: Low-Imp. Injectors on MS3X?

Postby NiceMan » Sat Apr 16, 2011 11:55 am

I run 2.5ohm injector whit 4.7ohm resistor in pairs and works nice and no cold problems...
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Re: Low-Imp. Injectors on MS3X?

Postby TerrenceLP » Sun Jun 17, 2012 10:36 am

Is the 8 Injector Peak and Hold Board ready for game time?

If not, any reason not to get the AEM 30-2710 10 Channel Peak & Hold Injector Driver box?

I'm on a 7M-GTE + MS3 + MS3x full sequential fuel & Spark off of a Toyota CPS, 24-1 dual wheel, HKS Denso 550cc Low-z injectors.

As I'm setting it up, I want to build a solid set up and my reason for the AEM is the lack of space left in the MS3 box.

any advice? :RTFM:
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Re: Low-Imp. Injectors on MS3X?

Postby Peter Florance » Sun Jun 17, 2012 1:47 pm

racingmini_mtl wrote:
Peter Florance wrote:I did some quick testing with Low Z injector and 3.3 ohm resistor, using the accelerometer pcb that I brought to 2008 megameeting
At lower voltages, there's a big difference in opening times with and without resistor. At 13.2 volts it was difficult to see any difference. That may explain my customers cold starting issues if battery is not fully topped off.
Perhaps I will be able fix with battery correction voltage...

Note this tester does not yield actual dead time measurements but I thought it would be useful as a relative test.

I'll probably be stating the obvious here but if there isn't enough voltage for a reliable or consistent opening of the injectors, no amount of battery voltage correction will help. That is the advantage of the peak&hold driver which will always give the maximum voltage available from the battery for opening the injectors. And the advantage of the LM1949 current sensing circuit over the PWM fixed time period is that the peak is always only as long as it needs to be.

Jean



I should have come back to this thread. What I posted is in fact not true; hard starting was due to some strange bug in fueling (req fuel in sequential) that seems to have been fixed in later releases.
The car starts fine now with a later beta than 1.0 release
Peter Florance
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60-2 Wheel LS2 Coils, Low Z Inj
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