Priming Pulse PW clarification

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linzerl
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Priming Pulse PW clarification

Post by linzerl »

I have always thought that the Priming pulse was a short pulse firing the injectors to purge any air and wet the inlet manifold.
However the logs attached show a very long injector firing duration of a giving PW.

For example,
Log A reports (cold engine) a PW of 3.6 ms..but the injectors fire for 3.2 seconds.
Log B reports (warm engine) show a PW of 0.4 ms..but the injectors fire for 3.5 seconds.

To log the priming pulse, the engine was running and logging, I stopped the engine (using Tunerstudio under engine control), then reset the ECU, again using Tunerstudio...

I was expecting to see a firing of the injectors for a very short duration...matching the PW of the Priming Pulse table.
Is there a reason for seeing what I am?

Many thanks....
Attachments
A.2018-02-13_07.35.00.msq
(285.03 KiB) Downloaded 19 times
A.2018-02-22_10_modified.msl
(186.57 KiB) Downloaded 19 times
B.2018-02-22_13.16.44.msq
(285.03 KiB) Downloaded 19 times
B.2018-02-22_12_modified.msl
(176.27 KiB) Downloaded 16 times
Last edited by linzerl on Thu Feb 22, 2018 2:56 pm, edited 1 time in total.
jsmcortina
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Re: Priming Pulse PW clarification

Post by jsmcortina »

Please post your datalog for the 'B' MSQ.

James
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ashford
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Re: Priming Pulse PW clarification

Post by ashford »

you're associating datalog "time" as pw.

aka "it injects for 3.6ms for 3.2 seconds". pw is a report field of injection time not an osciliscope trace.
Dennis_Zx7r
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Re: Priming Pulse PW clarification

Post by Dennis_Zx7r »

pw is the time the injector stays open per injection. As there's only one injection, the total time the injectors are fired would still be 3.6ms in your example.
There's no reason for the MS to calculate a new pw so it's constant for these few seconds I guess.
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linzerl
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Re: Priming Pulse PW clarification

Post by linzerl »

Thanks everyone for your help..Missing file added.

I now appreciate there's a dutycyle missing..if the injectors were in fact pulsing..I'm now thinking too along the lines that the PW value is being latched for a few seconds...possibly for the priming pulse delay/pump prime time (2 secs).

I'll test this and scope the priming pulse..but I started pulling the car apart last night...so it make take some time.

Thanks again..
jsmcortina
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Re: Priming Pulse PW clarification

Post by jsmcortina »

linzerl wrote:I'm now thinking too along the lines that the PW value is being latched for a few seconds...possibly for the priming pulse delay/pump prime time (2 secs).
Yes, this is how it works. "PW" was calculated for priming and because the engine isn't turning, that number stays there until the "stall timeout" occurs, the fuel pump shuts off and all calculations are reset.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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linzerl
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Re: Priming Pulse PW clarification

Post by linzerl »

Great..thanks
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