Injector Timing? Reference Periods? refereencing what?

[Wnts2Go10O]

my point is that you cant really calculate it for all rpm's and all manifold pressures... its a wide range of values...
theres no way to compensate... what value do you pick? you cant pick just one value...

it really doesnt matter in the higher rpm because of how fast the engine is running . at 80% dc or even 51%, the injector is open more than its closed (greg has said this). the issue at hand is low rpm injector timing where getting the fuel to mix as best is possible without losing any thorugh the exhaust is the whole name of the game.

for 1000-3400 rpm you are running in a very predictable area in terms of manifold pressure anyways.

it would matter (though not much more) in the later ecms where you can adjust according to rpm and not ect.

since u said it was closer to .006" lift that the gains occured, heres mine on the torquer 2 i have:
IVO is 30.5 ° BTDC ( - indicates ATDC)
IVC is 70.5 ° ABDC
EVO is 77.5 ° ATDC ( - indicates BTDC)
EVC is 25.5 ° BBDC

[MikeGyver]

... in the later ecms where you can adjust according to rpm and not ect. ...

Not both?

[Wnts2Go10O]

Not both?

errg, oops, you can for both but ect is more for low rpm than anything i think. SE was referring to the lack of adjustment based on rpm.

[Google]

Just an update for everyone.
Yesterday I was able to play with a 2003 Corvette on the dyno...
I moved the Injector Boundary Normal to a later event time.
What I noticed is that the vehicle gained torque until the point where the injectors really were spraying for more time than the valve was open...
it still increase a little as the rpm's went up but it was drastically less improvement in the upper rpm's
we gained around 10~15 ft-lbs of torque down low and 5~7 up top just from pushing the "Normal" value to a higher value
with his car, the cam is a 236 ish duration and it stopped making any improvements past 6.5 normal... I was moving in .25 increments
we still gained a hair more above that, but it could have been tire flex or other small fuel difference factors from run to run.
I didint play with it any more than that as we were already late in the day and I needed to get some street tuning done and we had already for the most part finished up the tune and werent gong to nit-pik over 1 or 2 horsepower

but moving the Injector EOIT to a later point with a cam, improved the torque across teh board...more noticeably down low in the RPM Range

nice..




..

[swebld]

How much effect could you get regarding Hydrocarbon (HC) Emissions in idle conditions with an average 23x cam, by pushing Injector Boundary as far as it needs ? Any ideas ?

[pontisteve]

Just want to add some food for thought to this interesting conversation. Random thoughts mostly, hoping to trigger an ahha moment for somebody else.

First, cam timing will vary from car to car based on cam degreeing accuracy. Next, the fellow a few posts back that talked about having the most overlap of the group... his tune file name says E85. Since it takes a ton more fuel with E85, his inj starting time would be much earlier, so his EOIT needs might be unique?

The injector size would have to be a huge factor in all this. Air intake velocity would be much greater during the first 1/3 of the intake stroke than the other 2/3 of the stroke. Even stock cams will have some overlap, just not necessarily at .050 valve lift.

This cam chart by Mark Olson might be a handy tool...
http://www.classictiger.com/mustang/...artCandDr1.htm

This Mustang EOIT table might be interesting to look at...
http://fordfuelinjection.com/files/T...tor_Timing.pdf

Seeing what the OEM engineers used as axis on the tables might be a clue as to what we need to be looking at as factors. With that Ford data, we're looking at RPM and load, and the general theme is that as load goes up, EOIT goes up. I'm thinking this is because MAP decreases (Ford doesn't use a MAP sensor, it uses MAF vs engine size for load calculations). Also, as MAP goes up, EOIT goes up, but only at higher loads. Also note the highest RPM they go to is 4000, which tells me the range Ford thought this mattered in is the 4000 and below range.

In regards to reference periods, are we really talking about TDC and BDC every 90 degrees here? Or is the trigger wheel offset by a certain amount, in order to allow the reading to take place BEFORE the motor actually gets to that TDC mark? Just like with ignition timing, we need to know where TDC is BEFORE we get to TDC, otherwise we don't have enough time left to actually alter the timing. Could this idea mean we're between 10 and 50 degrees off?? Greg mentioned we don't really know what we're referencing. Could this be why?

I'm thinking the makeup table is just for adding fuel for transient conditions (accel pump, etc), but even so, it should probably be modified exactly as much as the normal table right?

[Wnts2Go10O]

<snip>

In regards to reference periods, are we really talking about TDC and BDC every 90 degrees here? Or is the trigger wheel offset by a certain amount, in order to allow the reading to take place BEFORE the motor actually gets to that TDC mark? Just like with ignition timing, we need to know where TDC is BEFORE we get to TDC, otherwise we don't have enough time left to actually alter the timing. Could this idea mean we're between 10 and 50 degrees off?? Greg mentioned we don't really know what we're referencing. Could this be why?

I'm thinking the makeup table is just for adding fuel for transient conditions (accel pump, etc), but even so, it should probably be modified exactly as much as the normal table right?

boundary is in reference points after tdc, normal and makeup are to be finished by the amount of reference points after the boundary. now youre introducing another variable of crank wheel offset. the ecm is referencing off the crank wheel and where 0* is on the wheel or TDC.

[pontisteve]

So if I read you right, we're talking about 90 degrees for each reference point, and starting at zero on TDC Compression. At 6.5 x 90 = 585, we're talking about a boundary point of 45 degrees past BDC (1/4 of the way up on the compression stroke).

This makes sense, since that's probably close to where the intake valve would close, isn't it? And that would make a good boundary, or limitiation... sometime while the intake valve is still open (at the very latest).

The NORMAL injection target is delayed from this point by 2.55 x 90 = 229.5 cold or 5.55 x 90 = 499.5 hot. So cold, we're now at 814.5 (also known as 94.5), which would be about 4.5 degrees past half way down on the power stroke. This is right about the time the exhaust valve is opening, but the intake valve would already be closed, so we're shooting early on the back side of the closed intake valve, presumably to warm up the fuel more. Combustion would have just taken place, so this would also be the time when the intake valve and combustion chamber are hottest, which makes sense why they put it here.

Hot, we're talking about 585 + 499.5 = 1084.5 (also known as 364.5). That would be 4.5 degrees past TDC on the overlap (beginning of intake) stroke. Given a stock cam and injector delays settings, this sounds pretty close to where a stock exhaust valve would be closing... just past TDC. Since the motor is warmed up, we no longer need to be heating the fuel up by injecting it so early, so we switch to the strategy of injecting it as late as possible. This gives us the most possible head room for the longer pulsewidths that would come with higher load/rpms, and the coolest fuel possible in this now hot engine. It also helps prevent other cylinders from stealing this fuel from this intake port.

Those LS1 stock cam specs posted earlier were EVO 69 BBDC (111 absolute), EVC 33 ATDC (393 absolute), IVO 7 BTDC (353 absolute), and IVC 80 ABDC (620 absolute). If these numbers are right, the injector keeps spraying for 11.5 degrees after the intake valve starts opening. Of course, there's not much substantially flowing at this point, since cam ramps start out really slow at first. This seems like it would be about as late as they could get away with, but still basically injecting onto a closed valve.




I would also like to point out some confusion about cam vs crank degrees. While it is true that the cam runs half the speed of the crank, it's also true that cam spec cards are in CRANK degrees. The only time I am aware of that they actually talk about CAM degrees is when they're referring to valve overlap.

[pontisteve]

But Chris says this:

Boundary is the latest point in time that fuel can make it into the cylinder for the current injection period. It is measured in degrees AFTER TDC compression. It is also the earliest the injector can fire again after the completion of the last injection event. ie. the boundary defines the start/end of a complete injection cycle.

Normal End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the normal pulse (the main pulse) should finish. The hardware calulates the start of injection time from the EOIT and the desired PW.

Makeup End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the first makeup pulse should finish. Makeup pulses are extra pulses that can be injected to inject more fuel during an injection cycle rather than having to wait for the next cycle. There can be more than one makeup pulse but the makeup EOIT specifies the EOIT of the first makeup pulse.

The makeup PW minimum is a minimum PW for the makeup pulses, they cannot be shorter than this (if they are they don't happen).

So you have the boundary that defines the injection cycle, a normal EOIT that specifies the EOIT for the main pulse, and finally a makeup EOIT that specifies the EIOT for any makeup pulses that might be needed if a fuel increase is commanded during an injection cycle but after the main pulse has occurred.

Hope that helps.

Chris...

If this is true, then boundary and normal don't get added up. That means the EOI is at 499.5, which is 40.5 degrees before BDC Intake. That would be way into an open intake valve towards the bottom of the intake stroke. But when cold, that would be 229.5, which is 49.5 after BDC Power. That's way before the intake valve opens (at 353). This seems less likely. So which is it?

[LSxpwrdZ]

They are added together and the EOIT is based on the equation Bluecat came up with in his real world testing.

((Normal+Boundary)*90)-784 = EOIT in Crank Degrees

Don't believe me go look earlier in the thread and download his test data in the excel spreadsheet to see his results.

[BTLD_LS1]

the 99~02's are at 300.5 stock..


I calculate you actual EOIT as 377 degrees
which puts you at "Normal" 5.68
I would guess that you could add 25ish degrees to your EVC would get you close to your .006 value. putting you around 42* EVC ATDC or an EOIT of 5.96

try it and see how it responds....
I would bet that you will have to decrease your VE/MAF tables some after you change this value.

Thanks for the clarification.

I tried using both 5.68 and 5.96, however, I felt the car was noticeably richer smelling at idle. I did not notice a different in the wideband reading and the LTFT only reduced by about 2-3%. However, I may have other things effecting that. Im now running E85 with 2 heat range colder plugs, which I'm sure is not helping at all. Also, the car never hits over about 178* at anytime. Drove the car about 20 miles ~35 minute drive and got home and the head temp, using a temp gun, was only 165* and there was no pressure in the cooling system at all.

I might change back to stock heat range plugs and retry this.

[LSxpwrdZ]

Just wondering why you have such a large cam in a 347? You pull that thing out and put something in the low 230's intake and low 240's exhaust and it will make more power and torque everywhere. Not to mention idle better and smell less.

That cam is bigger than the cam I run in my 403 and I still consider mine decently large.

You went the wrong direction on the plugs. Usually when you put a higher octane fuel in the car you don't also go colder on the plug unless you are still running too hot. In your case a small motor like yours with a large cam has little to no dynamic compression and really doesn't need E85 over 93 octane.

[BTLD_LS1]

Just wondering why you have such a large cam in a 347? You pull that thing out and put something in the low 230's intake and low 240's exhaust and it will make more power and torque everywhere. Not to mention idle better and smell less.

That cam is bigger than the cam I run in my 403 and I still consider mine decently large.

You went the wrong direction on the plugs. Usually when you put a higher octane fuel in the car you don't also go colder on the plug unless you are still running too hot. In your case a small motor like yours with a large cam has little to no dynamic compression and really doesn't need E85 over 93 octane.

I was originally planning on building a 427 with some sponsorship form a local shop that was building LS1 motors, 1stLS1Perfomance. The guy that owned the shop had his mother fall ill and he moved to Washington and closed up the shop to take care of her. So my buddy was working on a forged LS1 for his 98, but the car got stolen and when recovered was destroyed so I got the internals cheap and just threw it together with a set of heads worked by SAM, when my motor with 200K miles finally gave up the ghost to a spun rod bearing.

And the colder plugs are a hold over from the nitrous and 91/101 mix I was previously running.

I know the car could make more power on a smaller cam, but really what are we talking about maybe 40-50 hp with the compression im running? The initial dyno was done at Pro Dyno and they figured with a real tune in the car I'd pick up 20-30 hp anyways.... Its not like I drive the car daily and it Im in the whole thing about 10K including the cost of the car or 3 transmissions I put in the car.

With the new 5K converter in the car I think its a solid 11 second car on motor, nothing to sneeze at and only time will tell on nitrous. And the car runs much different on pump gas vs. race gas. I've also always had the car running way rich as I was afraid to lean it out with the nitrous and blow it up again.

BTW u can only get 91 in AZ and E85 is about $.50 cheaper than 91 on average

[S2H]

Thanks for the clarification.

I tried using both 5.68 and 5.96, however, I felt the car was noticeably richer smelling at idle. I did not notice a different in the wideband reading and the LTFT only reduced by about 2-3%. However, I may have other things effecting that. Im now running E85 with 2 heat range colder plugs, which I'm sure is not helping at all. Also, the car never hits over about 178* at anytime. Drove the car about 20 miles ~35 minute drive and got home and the head temp, using a temp gun, was only 165* and there was no pressure in the cooling system at all.

I might change back to stock heat range plugs and retry this.

you might try changing your Boundary to 6.5 like the later LS1's and then redoing your "Normal" tables to fit the equations...
it could be an issue of how the math actually adds up for defined end of injection..
honestly I couldnt tell you without having you get on a dyno and test.. I just know that it helped on a tune I recently did.

[S2H]

and its not the nitrous that blows up the motor...
its detonation from too much timing, or having too much fuel and getting a sudden heat explosion thanks to the added oxygen hanging out...
running lean on nitrous will almost never hurt a motor...too much timing when lean is the real cause usually.

[BTLD_LS1]

Yea, Its really a non issue at this point, I don't think my single walbro will fuel the motor plus nitrous now, so I'm gonna focus on getting as much as I can outta the motor. The car was "slow" before due to the low stall speed in the converter, average 2.0 60 foot times

[S2H]

if you had a little smaller cam you wouldnt need that 5k stall..LOL
you may even need a larger stall than that...

[BTLD_LS1]

Lol true but the converter is dead on at 5k and to me it seems perfect for the setup...

[pontisteve]

Back to topic, there's only a few things we really need to know. First, how many degrees is a reference period. 90 seems logical, and was tested by bluecat.

Next, we need to know the initial point from which we start. One would assume TDC compression, but that isn't necessarily the case.

Next, we need to know which way the numbers are headed, left or right on my graph.

Finally, we need to know the relationship between boundary and normal. Is normal added to, or subtracted from, boundary.

I'll be satisfied when we have solid answers to all these questions, and also when we can use these answers to explain why the factory has their settings where they are. If that all lines up perfectly, then the theory is proven.

[WS6FirebirdTA00]

We already know, it was tested. Boundary+normal on the LS1 stuff.