EfiniX
(Member ++)
11/06/15 12:58 PM
Before I turn my boost down, one last thing to check... (voltage drop on WOT)

Well I couldn't be happier right now. Evan swapped my manifold (maybe he'll post pictures of the crack it had) and I finally got around to adjusting my global fuel to bring my LTFT's to zero (well, very close, anyway) and to get the highest cells in my VE table below 100. Car is running great, and for the first time, AFR and Boost estimates are tracking very close to actual values off my WB and MAP.

What I've also come to find, and accept, is that 23psi might be just a bit too much for my setup. Now before I turn the boost down, there's one last thing I wanted to put to the community.

I've noticed in my last pull that as my RPM's go up, my battery voltage goes down. Not a ton, mind you, but it is at 13.9v as I'm putting my foot down, and it slowly works its way down to 13.5v by the time I take my foot off the gas. During this time, I also see the FrontO2 voltage drop at about the same rate (relative). The O2 voltage starts at 0.88v, and by the end of the pull, it's at 0.80v. During this time, i don't see major fluctuations in the AFR's, although a few bounces between 11:1 and 11.3:1 could cause lean knock I suppose... In anycase, seeing this drop doesn't surprise me given what the car is doing, but I am curious how one compensates for it. I'm also curious if this could be the cause of the few counts of knock I'm seeing.

here's a still, link to the log file after the photo. Thanks in advance to anyone that takes a peak. If I end up with less boost, I don't really mind, but if I can leave it alone, well of course that's better.

FrontO2 is the thick, green line, 12v is the thick dotted red line just underneath...



And the log.
click


prove_it
(my racist jokes aren't actually funny)
11/06/15 01:55 PM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

You adjust the battery fuel adjust in the DA table. Can't think of name right off hand, but basically you adjust the deadtime per said voltage to tweak the injectors to deliver a bit more fuel as voltage drops. As battery voltage drops, voltage drops at the injectors and the fuel is no longer being delivered the same. So a deadtime adjust gives the injector more pulse as voltage drops which keeps the air fuel ratio the same.


This is what the Easy tune box works around. It supplies a constant 14v to the injectors no matter the load or rpm or charging system activity.


EfiniX
(Member ++)
11/06/15 02:35 PM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

Yup, I know it well. Saved me from an idle-drop issue I was having on a combination of cold/stopping/fans-on/headlights-on/other-stuff. The InjBatteryAdj isn't granular (and you can't add additional voltage plots), though, so I didn't consider it for this issue. That being said, i suppose I could increase the 12v value and leave the 14v value along to see if that got me anywhere...

i'll give it a shot and see what it gets me. thanks!



GSTwithPSI
(A hole)
11/06/15 06:22 PM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

FWIW, my battery voltage does the same exact thing. I've never seen any ill side effects from it, so I don't worry about it.

EfiniX
(Member ++)
11/07/15 09:29 AM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

Fair enough. I figure until I get a proper FPR and my IAT installed, I can suffer 22PSI

Mdlimy
(Member)
11/08/15 09:45 PM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

Although I cant give you much advice regarding your battery voltage affecting your o2 readings I will say that if you are getting knock from being too lean at 11.3 you should probably readdress your ignition timing or timing related trims. If an afr of 11.0 is keeping you safe from knock then you have some other issues you need to look at because 11.0 in my opinion is quite rich and could be compensating for something else that is causing the knock.

EfiniX
(Member ++)
11/09/15 04:01 PM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

Thanks. My trims looks great. I'm thinking that I'm just at the limit of what I can do with 92 pump gas and my current setup. I figure a T3/T04 turbo pushing 22psi is moving quite a bit of air, and without better gas (or E85 or meth), I don't imagine I'll get much more out of it.

GSXftw
(Member)
11/10/15 11:24 AM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

If this is E10 fuel, then no 11.0 isnt too rich, 92 oct sucks. Having my 1G on link for 5+ years, it ALWAYS dropped voltage during pulls. If it was a drag pass, it would usually be .8-.9V until I lifted off the gas, then it would come right back up. I did so many things to try and track it down... Upgraded big 3, saturn 96a alt to the back, it just always did it. It was load dependent and not simply RPM. I have seen a few cars not be affected by a pull, but most do this, and with the drop you see I wouldnt worry about it at all. The Injector deadtime for voltage table will take care of it, your only concern needs to be that the voltage for the fuel pump is probably dropping too, so if your pump or injectors are close to maxed you could look at improving it.

EfiniX
(Member ++)
11/10/15 02:26 PM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

The pump is wired directly to the battery (there's a fuse, of course), so I'm sure it's system load. I've been playing with my global fuel and VE table lately and I'm settled on where that's at for now. I'll do a few WOT pulls and see what things look like and adjust the battery injector bits if I'm still seeing a drop that tracks with a lean condition. It's so minor that I'm guessing I won't have to do much.

Mdlimy
(Member)
11/10/15 02:44 PM
Re: Before I turn my boost down, one last thing to check... (voltage drop on WOT)

Hey look we are all in oregon

In my opinion 11.0 is still rich even being e10, not so rich as to cause issues but almost all the cars I have tuned in the past few years have been on e10 and I have never needed to be below 11.5 to be knock safe and make good power. The dsm crowd seems to think on the rich side, and from what I have heard about the stock ecu it targets pretty rich anyways...but anything in the low 11s on pure gasoline or e10 is too rich imo.

Air/fuel ratio debates are a slippery slope and almost always don't end well, so i wont mention it anymore but my advice is that, if you cant lean out to around 11.5 without seeing knock, you should make some adjustments to your ignition table. I do agree that you are close to your limits without meth but I also think you could maintain that boost level with some time spent tuning.

Are you opposed to water/meth?

It would be cool if we could find an awd eddy current dyno in the pdx area to rent for the day and get all the gvr4s together and do some tuning.



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