Transient Fuel Stops Working above 3999rpm

[GHuggins]

I agree about the regulator and fuel pressure, just so expensive to do everything at once (good pump, regulator, etc) then if Im in there Im going to want to add a return. What's a good regulator to use anyway? However, there really should be some spike in Injector Pulse due to transient no matter how you look at it, and there is none ever above 4000rpm. Not sure if you've looked at the MAP and MAF spike you get with stock Throttle Rate Opening on the Whipples when shifting at high rpm? It's crazy high, all that pressure in the manifold gets blasted when you re-open the TPS fast at high RPM. My Procharger never did this. I could also switch to a Turbo or Automatic, either should take care of this.

This is what I was trying to better illiterate, but obviously failed miserably the last time

At this rpm level - "I would think or atleast believe that the MAF or VE models alike - if tuned correctly, should correctly fuel the motor" THAT IS if the fueling is maintained and correct. A PD blower due to the instant and tremendous spike in manifold pressure will actually cause a much smaller amount of fuel to be delivered than "requested" if fuel pressure isn't correct - REMEMBER - you have manifold pressure working against fuel pressure - so how does that 38psi of fuel pressure look now? I fought this and fought this on a 18psi PD blower because of fuel pressure being 12psi lower than what it should have been.

Yours is dropping to 38psi with how much boost fighting agains it? - Yikes....

We run the Squash dual in tank fuel pump configuration - does away with the fpcm all together on the camaros. Comes with vacuum and boost referenced regulator that you dial in. Can't put the regulator on the backside of the rails - Goes on the feed side... DO NOT use the supplied fuel line - highly recommend gates high pressure fuel line and use plumbing or automotive style crimp clamps to attach the lines... Other than this - not a bad system...

I'm aparently in the dark - going to look into the C.A.T.S system. Would just be nice if HP had all of this.... Seems simple enough to add?

[GHuggins]

However,,, IT would still be nice if there were some way to make transients work above 4000 rpms

Just wondering now if transients weren't originally designed to makeup for maf/ve incorrections or descrepentcies? SO when MAF comes into the equation, it's 100% in control?

[10_SS]

However,,, IT would still be nice if there were some way to make transients work above 4000 rpms

Just wondering now if transients weren't originally designed to makeup for maf/ve incorrections or descrepentcies? SO when MAF comes into the equation, it's 100% in control?

yea i mean, I get why fuel pressure pressure is required to make things work right, but also I know transient settings would be much cheaper and easier to simply add a little burst of fuel to take care of all of these things that may not be spot on. Megasquirt is so easy to setup due to this... just add a little primer shot of fuel at tip in, done, 75 iterations of my tune and start to think transients just dont work... 20mins of playing on the bench and bam... no wonder why my settings are only making <4000rpms rich and unresponsive at tip in. I also don't think proper fuel pressure will single handedly fix this once I turn my throttle rate back to stock because I also have this problem without transients, down low where fuel pressure only drops to 58psi at tip in. You can see the Inj Pulse just kinda leisurely climb up to full speed... it should always spike up fast, just overshooting then come right back down and maintain flow during severe MAF/MAP transitions.

My LT1 670hp Procharger didnt have transient settings and it had bad tip in stumble due to lean when I added a 2bar sensor and halved the injector flow, then i simply 3/4'd (reduced tune inj flow by a total of 75%) then adjusted MAP VE settings to compensate... that made it perfect.

In this case... its basically the same thing except Transient settings are here, but they disable above 4000rpm. A real shitter.

[cc-rider]

What about the Transient Fuel Enable Decay ("Enable Decay") in the transient section? Says transient fuel will not enable until this many crank pulses are detected.

What defines a "crank pulse"? A rotation of the crank?

[cc-rider]

Now Compare that Log with Full Speed THrottle Blade Opening to this one with reduced Opening Rate... (no spikes, even at higher RPM/Boost)

Attachment 56544

Crazy how that throttle opening rate change affects that. Your pics show it clearly. Have you looked into the ability to change the closure rate of the bypass valve on the blower? If there is a way to soften that blast when the bypass slams shut...that would effectively work just like your reduced throttle opening rate...and theoretically should work everywhere including about 4000 rpm. I thought I remember reading somewhere once about controlling the bypass closure rate of positive displacement blowers...

Perhaps the transients are working...but that instant blast is just too much of a hit for the system to respond to.

Nothing quite smacks the engine with boost like a PD blower.

[cc-rider]

Found a thread where a guy was having the exact same issue you are mentioning. I'm still reading it so I don't know the conclusion. But wanted to share it.
http://www.camaro5.com/forums/showth...=298155&page=5

Edit: Nevermind 10_SS...I can see you posted there! Thought I'd leave it here though for others who come across this and may want to read up.

[10_SS]

Crazy how that throttle opening rate change affects that. Your pics show it clearly. Have you looked into the ability to change the closure rate of the bypass valve on the blower? If there is a way to soften that blast when the bypass slams shut...that would effectively work just like your reduced throttle opening rate...and theoretically should work everywhere including about 4000 rpm. I thought I remember reading somewhere once about controlling the bypass closure rate of positive displacement blowers...

Perhaps the transients are working...but that instant blast is just too much of a hit for the system to respond to.

Nothing quite smacks the engine with boost like a PD blower.

We talked about adding a restrictor plate or jet or something.. but the Throttle Blade setting was much easier and it works ok. I know the Stock ZL1 doesnt have this Whipple type overboost spike problem, so people dont have any many problems, or they have Automatics, and dont see WOT opening and closing at high RPM.

Look at the pics I added showing clear examples that prove the transients dont work above 4000.

The Transient Enabl e Crank Pulse I imagine would be to time the added fuel to the airflow, so it doesnt puddle up, or arrive to late... I imagine.

BTW, the Transients settings we see are intended for WARMUP since you need more fuel also in transient with a cold engine/intake valve than when warm... but they carry all the way over to hot engine, based on the Intake Valve Temp (IVT) table that goes all the way up into Hot Coolant Temps.

Non whipple, and you probably dont need these settings as much.

[cc-rider]

Have you tried turning that delay way down to see if the transients can make the injectors respond faster? The stock setting for this are 56 (or at least in my KB supplied tune). I see you have 50 in yours. Have you lowered this way down?

[cc-rider]

One more thing to consider. Sorry...you really got my mind going now!

Since you're running the upgraded 2 bar system...you've got the ability to command fuel based on MAP/Boost. I assume you're running around 8 psi. You could take the area in the boost enrichment table from 0-7 psi (100-150ish KPA) and command some more fuel there. It might work to add a burst of fuel as the boost transitions through that area and provide enough enrichment to carry you through the boost spike period. Might have to play with it a bit. But since you're running a PD blower...you'll never be running for long periods of time in that transition range. Its either full boost or out...so this part of the boost curve could be played with and not affect the full WOT fueling.

[mourat]

Maybe I'm blind and don't see this in HPT but is this the table you need? I can't see your file in TC to check what it's actually doing but here is what e38 for corvette looks like. In HPT I don't see this table.

[10_SS]

One more thing to consider. Sorry...you really got my mind going now!

Since you're running the upgraded 2 bar system...you've got the ability to command fuel based on MAP/Boost. I assume you're running around 8 psi. You could take the area in the boost enrichment table from 0-7 psi (100-150ish KPA) and command some more fuel there. It might work to add a burst of fuel as the boost transitions through that area and provide enough enrichment to carry you through the boost spike period. Might have to play with it a bit. But since you're running a PD blower...you'll never be running for long periods of time in that transition range. Its either full boost or out...so this part of the boost curve could be played with and not affect the full WOT fueling.

the spike would be probably anything above 170kpa, I might hit 170 normally, but I see your point. However, PE enable is a whole different beast and I fought with that too. It tends to enable late when enabled by MAP pressure alone which is the reason I have ~15kpa MAP PE enable, and rely on TPS for PE entry which is what GM does with ZL1 I believe... (much faster than waiting for MAP to respond). One more reason for Transients to fill the gap. This may be due to the small MAP sensor. The GM COPO with the same exact Whipple parked at the Woodward GM Display had TWO, that's right TWO 1990 style large MAP sensors reading boost from it's whipple... thought about trying that, never did though. How I love to see what they use for a tune...

[10_SS]

Maybe I'm blind and don't see this in HPT but is this the table you need? I can't see your file in TC to check what it's actually doing but here is what e38 for corvette looks like. In HPT I don't see this table.

nope, HPT has this.

gain vs RPM.PNG

[cc-rider]

Yeah I think I remember seeing somewhere that PE entry with throttle was quicker than MAP. But the way HP Tuners explains it...the tune will take whatever table is richer and use it. Might be worth playing around a bit. Maybe if you keep using throttle for the majority of your PE fueling but drop in a blast of fuel in the boost enrich table early in the transition (105-125 kpa) then it may kick it by the time the over shoot happens up in the 170 kpa range.

Sounds like you have a lot of logging data playing around with boost PE. If you have some data on what the delay is you may be able to time it...

[10_SS]

Have you tried turning that delay way down to see if the transients can make the injectors respond faster? The stock setting for this are 56 (or at least in my KB supplied tune). I see you have 50 in yours. Have you lowered this way down?

I just played with this. Looks like it's a delay from Engine start... so 50, Transients start working right away. 5000, they pretty much start working ~20 seconds after startup. 10,000 transients start working after about 40 seconds both tested running at 3400rpm. Was really hoping 0 would fix the problem... dang

[mourat]

LOL I knew I saw it in HPT before! Long day

[10_SS]

LOL I knew I saw it in HPT before! Long day

took me 5 long mins to find it.. so yea I know how you feel. I actually switched between Basic and Advanced View... lol

[schpenxel]

If you go under edit-->parameter navigator there is a search feature where you can search for parameters. Not something I use often but it's there if you ever want to search for parameters

[cc-rider]

Hi guys. I wanted to bring this thread back to life again. Because I think I've got some evidence of a transient occurring above 4000 rpm. I've posted a picture below. I did a high rpm shift with a stomp back into the next gear. The RPM's never fell below 4000 rpm and yet I have a injector pulsewidth spike that can clearly be seen in the log. I assume that a pulsewidth spike is how we would measure a transient occurring in the data? Here is the logfile as well...this occurred a couple of times in the log...just look for big boost shifts where I was rowing through a couple gears.

Transient above 4000 rpm.jpg

Drive 12 in VE.hpl

I'm not sure what to think of this. Wanted to post it here. These are the stock Camaro SS LS3 transient settings. Its obvious that the transients are way off and need to be adjusted. You can see a lean tip in and rich tip out on just about every throttle movement. But I thought seeing this pulsewidth spike was interesting.

Any thoughts? Is this truly a transient fuel shot I'm seeing here or is this some other thing going on?

[10_SS]

Hi guys. I wanted to bring this thread back to life again. Because I think I've got some evidence of a transient occurring above 4000 rpm. I've posted a picture below. I did a high rpm shift with a stomp back into the next gear. The RPM's never fell below 4000 rpm and yet I have a injector pulsewidth spike that can clearly be seen in the log. I assume that a pulsewidth spike is how we would measure a transient occurring in the data? Here is the logfile as well...this occurred a couple of times in the log...just look for big boost shifts where I was rowing through a couple gears.

Transient above 4000 rpm.jpg

Drive 12 in VE.hpl

I'm not sure what to think of this. Wanted to post it here. These are the stock Camaro SS LS3 transient settings. Its obvious that the transients are way off and need to be adjusted. You can see a lean tip in and rich tip out on just about every throttle movement. But I thought seeing this pulsewidth spike was interesting.

Any thoughts? Is this truly a transient fuel shot I'm seeing here or is this some other thing going on?

I think your getting a Low Fuel Pressure Injector Compensation, as your Fuel Presure drops to 23psi right there... but what came first, the loss of fuel pressure, or the injector Pulse spike, before Fuel Pressure dropped to 23psi it was at ~45psi, and before that it was 65psi...

but then there's other places you have solid FP and have some injector spike right around 3900rpm shifting, and then some at 4050RPM, but then no inj spike at 3900 shifting... so i dunno...

FP_Drop.PNG

[cc-rider]

I think your getting a Low Fuel Pressure Injector Compensation, as your Fuel Presure drops to 23psi right there... but what came first, the loss of fuel pressure, or the injector Pulse spike, before Fuel Pressure dropped to 23psi it was at ~45psi, and before that it was 65psi...

but then there's other places you have solid FP and have some injector spike right around 3900rpm shifting, and then some at 4050RPM, but then no inj spike at 3900 shifting... so i dunno...

FP_Drop.PNG

You're absolutely right. I didn't even notice that FP drop. It has to be what caused what I thought was a transient.

Good call....no way this is evidence of a transient above 4k.

These damn FPCM controlled systems. GM got too cute with their engineering.