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Changed from 1650cc injectors to Siemens 2000cc injectors and now can't start.

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The car is an Evo3 running a series 1 AEM EMS. It was running fine on 1650cc low impedance injectors, using the resistor pack. The injectors were changed to some used Siemens 2000cc low impedance injectors and now the car cannot start. The injectors don't appear to be opening at all. There is no evidence of fuel at the tip and you cannot feel or hear the solenoid actuating. However, after taking out one of the injectors and putting direct power to it you can feel the solenoid actuating.

Checking with a meter confirmed that the injectors are low impedance. We tried increasing latency values significantly with no change. Even tried a stock Evo3 ECU with ECM link with the same result.

Some guys are telling me these injectors won't work without a peak and hold driver but I have never heard off or come across a low impedance injector that cannot work with a resistor pack. Is this a possibility?

I am wondering if the injector internals are rusty from running ethanol and don't open easily. Once the fuel pressure is at the back of it the magnetic field is not strong enough to open it. The injectors are going to be tested and cleaned tomorrow to see if anything is wrong with them.

What it says in the help file for 'peak and hold' injector drives is:

"Peak and Hold Control

Peak and hold injector control is a two stage system for driving low impedance injectors. Peak and hold provides the advantages of fast opening times (dead time) compared with ballast resistors and low power consumption when holding the injectors open.

During the peak stage, the injector drive turns hard on and the current rises towards the maximum injection current. The ECU detects when the current reaches the defined 'Peak Current', at this point the control switches to hold mode.

Once in the hold stage, the ECU is acting as an ultra efficient ballast resistor limiting the current through the injector. "

What these injectors may need is a surge of power to open them initially and no resistors. Another option is the OEM resistor pack is wrong for these injectors, what is the measured resistance difference between the old and the new injectors?

6 ohms for the old injectors and 4 for the new ones.

I've never attempted to run the p&h siemens injectors with a saturated drive but I wouldn't mind betting that they need a higher peak current than they're currently getting.

On the flip side I've seen numerous injectors that have sat for long periods and won't initially operate at all. Often pulsing them directly with 12V (briefly) will get them operating but if that's the case I'd definitely have them cleaned and tested to ensure they are flowing equally.

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