$51 inj pulse too high first crank but 2nd fine

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$51 inj pulse too high first crank but 2nd fine

Postby VX L67 Getrag » Wed Jul 16, 2014 11:45 am

Just wondering if there is something simple to change as I'm using the exact same tune both cranks but first crank won't fire well enough to keep running!

2nd crank on the same exact tune 1 minute later it fires & runs fine & looking at the logs the only change is the inj pulse is nearly half as much in 2nd start.

It's lower in both the crank period & also once in running period, I've tried lowering crank pulse width & cold start multiplier but not perfect & seems strange the 2nd crank doesn't need these lowered?

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Re: $51 inj pulse too high first crank but 2nd fine

Postby VX L67 Getrag » Wed Jul 16, 2014 1:11 pm

If anyone wants to have a look here's the log of 1st crank fail & 2nd crank start with the associated ADX.
Attachments
VS_V6_SC_$51_Enhanced_v1.0.adx
(155.54 KiB) Downloaded 112 times
2nd crank.xdl
(126.91 KiB) Downloaded 122 times
1st crank.xdl
(2.64 KiB) Downloaded 111 times

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Re: $51 inj pulse too high first crank but 2nd fine

Postby VX L67 Getrag » Wed Jul 16, 2014 7:22 pm

I know the inj pulse is just based before the PCM starts off the crank pulse & then after it's in running mode it's in injector multiplier vs all the other variables & cold start tables, but why does it change so much from initial crank to the next start crank is there something in the code that changes if it has crank recently to use a different scalar or something?

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Re: $51 inj pulse too high first crank but 2nd fine

Postby VL400 » Wed Jul 16, 2014 7:44 pm

It changes as the PCM detected the engine ran but only briefly. There is a multiplier table for adjusting it, in the $51 XDF its Crank - Fuel Pulse Width Multiplier V's Ref Pulses (Table B)

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Re: $51 inj pulse too high first crank but 2nd fine

Postby VX L67 Getrag » Wed Jul 16, 2014 7:47 pm

Oh cool thanks VL400 so which way would I adjust it as I'm not sure how or what it references?

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Re: $51 inj pulse too high first crank but 2nd fine

Postby VL400 » Wed Jul 16, 2014 8:13 pm

Table A normally, table B if it was a short run. Make B the same as A and there wont be a change 2nd restart if it stalls.

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Re: $51 inj pulse too high first crank but 2nd fine

Postby VX L67 Getrag » Wed Jul 16, 2014 8:33 pm

Thanks heaps, I will have a play tomorrow & see!

Thanks again, the pulse after it actually fires isn't as high either does it adjust the trim pulse after fire for a little while too?

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Re: $51 inj pulse too high first crank but 2nd fine

Postby VX L67 Getrag » Thu Jul 17, 2014 7:15 pm

Well copying ref b table to a worked, it's a bit weird though as it tries to run after a couple of seconds & if I had of let go of the key it would have stalled but kept cranking through it & it fired up (first go sort of).

Is there any documents that show what the code/software/pcm goes through in it's start up to run point?
Attachments
1st crank start.xdl
(158.61 KiB) Downloaded 105 times

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Re: $51 inj pulse too high first crank but 2nd fine

Postby VX L67 Getrag » Thu Jul 17, 2014 7:33 pm

Just to make it easier to see I exported the first 20seconds with all the main stuff needed for cold start.

You can see the inj pulse got a bit low just after the PCM went to run code, but not sure how to seperate so it has a more even inj pulse?
Attachments
cold start.xls
(60 KiB) Downloaded 113 times

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Re: $51 inj pulse too high first crank but 2nd fine

Postby antus » Thu Jul 17, 2014 9:41 pm

Look at cold start enrichment options
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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