Cold start overdriven hpfp rattle fix needed

martymil

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Sep 6, 2017
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Ok so I came across the hpfp fuel pressure valve rattling trying to control pressure when on cold start with cold start enabled or not.

This only happens when the hpfp is over driven or where a larger hpfp is used as its targeting over 2000psi at idle.

This happens with shotgun or helix and also heard of s55 style overdriven pump do this when the car is cold and the water is under 104f.

Once it reaches the temp the fuel pressure just drops to a sensible 600 to 800 psi and hpfp fuel pressure valve rattle stops.

Its not really an issue but it sounds horrible.

Could it be fixed and have a check box for ones overdriving their hpfp fuel pump ?

@jyamona @Twisted Tuning
 
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KClemente

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Did you manage to solve your issue yet? c_t_cur_vcv_ctl_pre_run seemed to work for me. I set it to 5 seconds and it lasts just about that long. Stock is 20 seconds.
 

KClemente

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IKM0S

Minimum time for VCV pre run duration (c_t_cur_vcv_ctl_pre_run)

Address: 4C25A

Cell Data Size: 8 Bit
LSB First

Low range: 0
High Rang: 25.500

Conversion: X*0.1

Enjoy :)
 
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doublespaces

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Oct 18, 2016
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So... When I was testing the helix I complained about this and through various startups I figured out more or less the same thing. The problem is that nobody was able to fix it. So, being the amazing person that I am, I pulled some strings and got @AzNdevil the OLS data necessary and he spit out the tables needed and Chris at Motiv tested them with @AUbeast86 who confirmed they worked.

So if you want them ported, I'd start there.

Also, I don't know that its a valve though, it was something else entirely a clacking sound, much larger than a little valve.
 
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KClemente

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@martymil try timing the noise and see if its around 20 seconds (default value) I don't quite know how things would change if we were to set it to 0 so I just set it to 5 seconds.
 

martymil

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its until it reaches 104f water temp every time.

Once you hit the temp the sound stops and HPFP pressure drops.
 

doublespaces

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its until it reaches 104f water temp every time.

Once you hit the temp the sound stops and HPFP pressure drops.

There are two tables that were defined, one for switching from homo to homo-cold and the other is for homo-cold to homo. The XDF was in celcius by the way, so 40* is the kick over. Change it to 5*c and your car should start up and within a couple seconds be in the quiet table.
 

martymil

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Yeah I think the issue is getting the tables ported over to IKMOS which we are waiting for @jyamona to do.

He said he would look into it when he has time.