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“If injection timing is 132 degrees BTDC firing, start of injection, it means that you spray fuel after the port closes. The mixture vaporizes in the port and is drawn in during the next cycle, assuming its lower load and you're at low duty. On a piston engine this is called closed valve injection.
If injection timing is 270 BTDC firing, start of injection, you are spraying into an open intake port. On a piston engine this is called open valve injection.”
“So when Haltech is saying that 270 degrees is the preferred injection timing, what they are saying is that they want the end of injection to be near the end of the intake stroke. Basically, they want open-port injection (analogous to an open valve injection on a piston engine). The confusing thing is that based on my own reckoning the stock FC and FD ECU is based on fixed start of injection timing. So you can't really compare them easily to an aftermarket system. This is why knowing the reference point in the software is important, because it is often based on the waveform of the crank angle sensor you are using, and there could be some kind of crank angle degree offset between that and true TDC/BDC.”
This helps to understand the degrees and span of injection window.
According to Haltech Matt, we could experience better top end power and some say better throttle response.
The idea of injecting while the port is open seems better suited to me rather than closed port injection and slamming the air/fuel charge up against a closed port.
I suspect if you have a ported engine with earlier/later port opening/closing then the 270-330 values could change.
Basic/Load Settings: Injector Dead Time, Injector Small Pulsewidths, Injector Timing tables
Of these three settings screens, which we are going to leave as default for now, Injector Dead Time and the Injector Timing tables are the most important. Injector dead time is the time in mS it takes for the valve in the injector to react and begin injecting fuel during the pulse. Setting this correctly requires measurement of each individual injector (it is configurable per injector). So unless you have this data available, leave it at the default 1mS. You can still tune the car but if you intend to refine your tune to the absolute finest degree, knowing each injectors dead time becomes important. For most people though, the defaults are fine. The Injector Timing table literally defines the degree of eccentric shaft position at which the injection cycle stops. This is the "sequential" in "sequential injection". Most useful at low loads and low engine speeds, it is beyond the scope of this base map to fully tune injector timing. For now, leave it at the default of 360 across the board. Later, once the VE table is tuned, you can read up on tuning injector timing if you want to further refine the tune.
Make no mistake, tuning injector timing properly to your engine will result in a far better tune which will return a smoother idle, higher fuel economy and less emissions as well as more power and engine response. But until the VE table is tuned and the rest of the settings dialed in, playing with injector timing is just going to complicate things. Here's a hint though: things are rarely most efficient when injecting fuel into an open port. OEMs try to inject fuel on the back of a valve or into a closed port to form a perfect cloud ready for the intake event to take place.
So another can of worms is “Injector Angle Split”. Mine is set at 0 across the RPM range while S4, S5, S6 & S8 base maps show values of;
0 RPM – 15500 RPM
60 - 70
And LMS-689 has this juicy info from the Haltech forum;
“You can only start the secondaries based on load, not rpm. You define the load they will begin to operate in the fuel setup page. Injector angle is just that, the angle BTDC the injector will close. Meaning all the fuel will be in at that point. The opening time is calculated back by the ECU depending on RPM. At high RPM/high injector duty, you're not going to find much power in manipulating the injector angle anyway. The split angle is the difference between the primary and secondary. You can compensate for the secondary injector typically being further up the intake tract. Add angle to have the secondary injector open and close before the primary. A 0 angle will have them pulse together.”
Corrrect way to set up injection angle at any given load and speed is through dyno testing. Targeting for certain AFR and then adjusting injection angle until richest output lambda is observed - most of the given fuel amount contributes to combustion.
Still, to have really good control over air-fuel mixture inside chamber, one would have to use large fuel injectors and high pressure, to operate at much lower duty cycles than are usually considered as "safe". They may be safe from standpoint of injector itself, but aren't safe from control standpoint of charge preparation for each rotor flank. It may work ok in normal situations, but overboost fuel cut or traction control fuel cut when one injection pulse can overlap two chambers would cause certain issues
Every thing seems to work at 0°, just would like to know if this is optimum for my S4 stock injector locations.
I have yet to change the Injector Firing Angle or Injector Angle Split values. I’m just trying to get a consensus if this is the right track.
Idle AFR not affected.
Car drives smoother in city/low load.
Secondary transition seems smoother. Using 550 OEM primaries & ID 2000 secondaries staged at 1.0 PSI.
I need more driving time to see if other characteristics have changed.
I also changed my injector angles after seeing the video from Haltech on "How to Tune a Rotory".
I daily an FC with a Sprint RE.
Before my angles were 150ish to 190is from 0 to 10,000 RPM.
I made the change and also notice the car drove better. alil smother city driving which is 99% of what I do. My car is my daily. I also noticed immediately that it was less fume-y especially windows open 30-50 mph... it was pretty bad like I had an exhaust leak.
I also noticed better vacuum at idle. I have a street port and usually was at 17.5inches now Im over 18 at 800 - 900 rpm. The higher vacuum also appeared on the highway where at 70ish MPH 3000ish RPM I would have 8-9 inches of vacuum now Im pulling around 11.
Power up to redline 8500ish also didnt fall off as much as before. Im still on the stock turbo which dies hard around 6000 on my motor.
i didnt noticed much difference when i fixed my settings.. other than running slightly richer at low rpms, so maybe a slight MPG improvement after leaning the fuel back out
I must say I've noticed a significant difference in low end performance, fumes, and overall smoothness.
Creeping around in 2nd gear at low RPM is so smooth now. It used to buck a little if you let the RPMs drop under 1300. Also seems more torquier in the low range.
Excellent thread. It isn't everyday that you come across a post with some forethought!
I'm interested to know what kind of results are had with increasing the angle to account for the additional overlap of a heavily ported engine. I would assume that if you were trying to spray into the open port for the duration of the opening then there would be some positive benefit, however I can't see how increasing the injector angle in a heavily ported motor would change much if you are just spraying it into a closed valve situation.
Umm, Ill discuss it with my tuner when the time comes.
Would be good to hear others opnion.
Really having a less fumy running engine would be the biggest advantage for me. But the Haltech guys cant be the only one with this issue. What at the other ECU guys injecting at?
Didn't even notice this thread until now. Pardon my lack of knowledge of all the individual firmwares of various Haltech products. We are talking about start of injection in all these discussions/maps right? So if you set it to 270, you are spraying into the port during overlap, where hot residual gases are being pushed into the intake port. Then the port closes, so if the duty cycle is high enough part of your fuel is going to sit in the port until the next intake event. The reason for closed port injection is more time for fuel to vaporize.
With start of injection being fixed you are accounting for flight time as rpm changes, and changes in injection duration based on load, and change in mixing depending on the amount of scavenging or residual gas. If it's fixed end of injection it's easier to tune. Set the end of injection according to port timing and you can predictably always have open or closed injection timing.
Remember, even if you set your SOI to 300 degrees, and intake port closes at 220, If it takes 100+ degrees to deliver fuel (convert duty cycle to degrees) then a lot of the fuel is spraying into a closed port.
If any of you have access to an emissions analyzer, you want to tune injection timing for lowest HC and CO emissions (before any cat). HC emissions concentration are proportional to unburned fuel, wasted droplets passing through due to wall wetting or misfire. CO emissions concentration are proportional to target AFR but also to quality of mixing.
I assume less smoke is more complete combustion. Could you see a difference in AFR's?
I also found this diagram. I think <3000 RPM is 445 degrees ABDC and >5000 RPM is 355 ABDC degrees, which puts injection in the middle to end of injection window. (See diagram Post #1).
Last edited by TRRAPLN; 12-05-16 at 11:00 AM.
Reason: Add Pic
No didnt see it in the AFR's but I wasnt looking that closely.
Yes, just assuming less smoke was a good results for a better burn (Ive not changes my plugs in a while and still on a very basic tune)
In that above attachment why are you now talking ABDC? (not BTDC)? Im assuming its to do with Haltech injector timing based on the End of injection time (and attached report is based on start of injector time?)
Havoc, I'm talking ABDC to match the little red numbers in diagram in post #1. I'm not sure I interpreted that correctly, so maybe someone else can confirm my numbers are correct.
Yes, I see the diagram implies it is the start of injection. We would have to add our injection duration in degrees to convert to end of injection. Help arghx.
Also this states that injection occurs later in low RPMs and earlier in higher RPMs. Which makes sense to me, however it is contradictory to Haltech's recommendation of 270-330.
05-29-16, 09:01 PM
Help arghx.
