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Discussion Starter · #1 · (Edited)
Plz post what your max HPFP psi readings are coming up on your AP with a pro tuned, stock HPFP after spirited driving.

I am seeing some pretty high fuel pump max psi readings of over 3700 on my AP after a new tune. The latest was 3722psi. Should I be worried about that? The steady state under load at high rpms is set to approx 2950 and I see that in real time and on my logs. But the spikes occur when I lift the throttle and while shifting. I'm curious what others are seeing.
 

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Discussion Starter · #3 ·
Ok, Thx. I will review. But what I am really looking for is the max sample and hold value shown on the AP after a drive which may not be caught on a particular log. The AP is looking over hours not seconds of driving.
 

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Easiest thing to do in your situation is just record the min-max after each spirited drive and see if it's just an abnormality or a trend with the tune.

The tune would be a big factor in what the pressure rises to so other people's set ups might not reflect the same results.
 
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Discussion Starter · #5 ·
I’ve got a stock pump and forgot to post that. The over pressure spikes I see in my logs are just as I lift off of wot then it goes quickly down to commanded pressure. I’m just concerned about over pressure for the fuel rail, injectors and pump. I have seen upper 3700s as a max spike.
 

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It's quite possible that the max numbers you are seeing on your AP is noise. All the AP does is display what the highest value it "see's" in it's data stream coming from the sensor, doesn't necessarily mean it is the case.

I would take a few data logs at different conditions: idle, cruising on the freeway, starting from stop with a 1-2-3-4 shift and a full 3rd or 4th gear pull. Be sure you are recoring frpactual, accel pedal pos, etc angle and lowside fp actual. Try to see if you are consistently hitting that high of a pressure and at what condition ie lifting off after a pull, etc.

FWIW, I took a look at the several data logs I have from the 3 different tunes I've had and max I got was around 3.6k psi, which was 1 instance compared to more typically around 3-3.2k
 

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Discussion Starter · #7 ·
Yeah thx, I have done most of that and logging the correct parameters and see nothing abnormal except for the spikes after lifting under a high pressure condition. The logs usually show a spike up at that point. Your 3600 spike is similar so what do you think of that and is it an issue? If not, and other guys have similar spikes at lift then I’m good with it.
 

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Discussion Starter · #8 ·
Magertron - Thx, that's really helpful to see. Yes in your log I see that 3285psi spike and that's what I'm talking about. But mine is 3690 in my last log. BFF above is seeing 3600. My post was to get some more of these from you guys to see if I'm in the forum ball park for max spike psi.

I did notice that a lot of your log results are very similar to mine like Boost, Load, AFR, AirFlow Mass, LowSide fuel psi. imo - your knock counts do seem high. I see 0-1 in my logs.

Again, Thx!
 

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That link has both 3rd and 4th gear pulls.

Yeah, knock events were happening in that log as I'm still getting the tune sorted by Stratified.

I still don't think that your rail pressure is much of an issue, if it was spiking above 4000psi then that is cause for alarm. You may have just won the machining lottery with how well your fuel system works.
 

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Got them listed in my forum tag man.
 

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Discussion Starter · #15 · (Edited)
I see what he wrote. But I have an OE pump and the demand to actual pressure is not the problem. It is very close under normal conditions. It's the overshoot spike on throttle lift that goes up to 3600+ then down immediately.
 

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Thought I'd look in the service data to see if there was any info or diagnostics on fuel pressure.

There is this chart in the RS service data:
Font Material property Number Screenshot Symbol

So you're getting up there with 3700 psi, but it isn't out of range. Nothing really conclusive from this, but thought it would be good information to know what the car thinks is the maximum.
 

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I read up last night that Bosch fuel rails are rated to over 5000psi, not sure about the injectors though.
 
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