ECU Start Signal

Thanks. I understand it is to help the engine start - but how specifically? It seems that at the starter motor speeds (200+ RPM?) the fuel pump and injectors are running, so what else is needed?

Thanks, Andy

Hi Andy,

before you ask me again and again: Why do you not just tell me what you are really after?

You wrote: "starter revs are nor enough to convince ECU of a running engine. It would normally not activate fuel pump." I tested that with my ECU and the fuel pump was on.

So what test can I perform on an ECU to see the effect of the start signal?

Or does my ECU have a fault and is running the fuel pump when it shouldn't be?

Thanks, Andy

Hi Andy,

Your starter does not turn your engine at 200 rpm. I am sorry but I will not comment further as I have already written all I have to say.

Even if the starter motor only turns the engine only at 50RPM then the fuel pump turns on. Is the issue that the starter motor speed is inconsistent? Is that what confuses the ECU and requires the Start signal?

Your site makes me think you test ECUs. If so then I presume you must know the test criteria for the start signal.

Any help with this understanding this basic ECU functionality is greatly appreciated.

I didn't find any detailed information about it online so I am wondering if nobody really knows how it works in detail enough to actually test it.

Thanks, Andy

Dr-DJet wrote:

Hi Andy,

Your starter does not turn your engine at 200 rpm.
 

I hooked my starter motor up, disconnected the ignition coil, connected my scope to the tach signal from the distributor and turned on the starter. I get:

  215 RPM

Andy