Disconnecting Inductive Injectors whilst running: Damage?

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Disconnecting Inductive Injectors whilst running: Damage?

Postby Experimenteer » Sat Aug 21, 2010 4:33 pm


I know that you cannot disconnect piezo injectors whilst the engine is unning as they injrctor would stick open, but I was wondering if it is possible to cause damage by disconnecting an inductive injector whilst as engine is running?

Has anyone very done this and not encountered a problem such as damage?
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Re: Disconnecting Inductive Injectors whilst running: Damage

Postby NigeC » Sun Aug 22, 2010 9:32 pm

Wouldn't damage engine as they need current to open, but I'd be wary of where the voltage spikes to.
Nigeiometric efficiency = 14 wrong : 1 right....
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Re: Disconnecting Inductive Injectors whilst running: Damage

Postby JamesD » Sun Sep 12, 2010 6:10 pm

Hi, I guess that you are talking about solenoid injectors fitted to a common rail diesel?

If this is the case, then typically there is no problem with disconnecting this type of injector, but as Nige stages the capacitor discharges it's 80v which could cause a problem within the ECU.

I have seen cases where a long term open circuit injector corrupted the memory within an ECU, specifically the immobiliser, leading to a non start condition.

One reason for diaconnecting an injector whilst the engine is running is to determin a missing cylinder. If you use the pico high amps clamp you can do a relative cranking test (depending on the use knock the inertia switch, unplug the pressure regulator or cam sensor to prevent the engine from starting). This will help illustrate any mechaincal faults.

You can use pressure regulation percentage and the pressure sensor voltage, or serial data (injection correction) or the current clamp (injector pulse width variation) to indicate pressure drop through faulty injectors. Final confirmation can be achieved with an injector leakoff test.

We cover these procedures (using Pico) on our one day Common Rail Diesel training courses.


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