When do injectors operate

Hi,

I am rebuilding a BMW e9 3.0 csi. Before I build up the complete engine, I want to test the injectors on the car. I can only take the injectors out when the intake manifold is off the engine. I also need to disconnect the air MAP sensor. Should the injectors still work when i try to start the engine?

I know the injectors are working on there own. I have tested them apart from the car with 3v.

thank you

Hi Mich,
Not sure whether I fully understand ur question.

Injectors operate

• while cranking the engine
• [when engine runs above 250 rpm, read via trigger points/li]
  
• on cars other than BMW injectors are switched off in overrun-shutoff
• injectors will not work if +12V is not applied to pin 24 of ECU
• ECU will not operate if MAP sensor is electrically disconnected

Thank you. That is a clear answer.

I had 4 injectors that did not work. I changed them for good ones. All the injector work if I test them by hand on 3v. But 3 dont work in the car when the engine is running. I have tested the wires of the injectors with a 5w light. The light flashers.

If I put 3v on the injectors when the engine in running ,the injectors works.

What you be the problem? Too low voltage from ecu to the injectors?

Thank you.

Hi Mich,
do the injectors fail to spray or don't they 'click'?

The electrical pulses are very short - in milliseconds range. Quite often injectors are partially clogged and operate under '3 Volts', but not under operation conditions.

Spend the money, send your injectors to a reliable 'ASNU' - service and they will work as new afterwards in most cases.

Regards
Norbert

Hi,

when you touch injectors with you rhand, you will feel if they operate. If you are in doubt, I also recommend an ASNU service on them.

Hello,

All 6 injectors work if i operate I connect them directly to 3v. That why i assume that the are all working.

If I put the injectors in the car:
3 injectors work in the car
3 injectors dont work in the car