Injector End Angle Tuning

[81 TransAm]

I know this has been talked about many times, but I thought I would let people know what worked for me. Not having access to a dyno, I had to tune by how it felt driving. When I first switched to sequential MPFI I was using V3. It didn't have much options in V3. My IEA was at 0° (BDC on intake stroke) when I started tuning. I had a very pronounce stumble just of idle. I couldn't tune it out no matter how rich or lean I made it. So I switched the IEA to -180° (TDC on intake stroke) and the problem was gone. Then V4 came out and I had an IEA table to work with.
I already knew it didn't like an IEA of 0° at idle, so I decided to move it further ahead and spray the fuel on a closed intake valve to see what it would do. It didn't like that either. The AFR at idle got very erratic. Probably because I had too much valve overlap. Fuel coming in the intake valve and right out the exhaust. So I looked at my cam card and found the exhaust valve closing point. For me it was 21° ATDC. Then I looked at some datalogs I had of it idling, and found my IPW at idle. Then I found a link to a site that Danny provided, that gave me the number of crankshaft degrees the crank would turn at a certain RPM in one msec. Get this number and multiply it by your IPW and you know how many crankshaft degrees your injector is open at idle. Then I positioned my IEA, so the fuel would start to spray just after the exhaust valve closed. This gave me a very stable AFR at idle with no off idle issues.
Then I looked the my cruise areas. At -180° IEA at about 2200 to 2500 RPM, I would get a slight surging, not much but I could feel it and the AFR would jump lean every so often. Kinda felt like your A/C compressor kicking on & off pulling the engine down a little. So I did the same thing I did in the idle area to the cruise areas. I picked 2000 RPM & 2400 RPM. Then I blended the areas in between together. This fixed the surging problem and now my AFR at cruise is a flat line. It has very little movement from my target of 14.7 AFR.
For the WOT, I decided to go with S2H's (Scott) method in post #13 of this thread: https://forums.holley.com/showthread...-Phasing-Table. I did this because my Duty Cycle at WOT was at 70% at 6000 RPM. So I wanted to get all the fuel in before BDC on the intake stroke. From what I have read, bigger injectors would reduce my Duty Cycle and then tuning the IEA at WOT may give me some benefits, but for now it feels real good at WOT.

Danny, I tried to find the link to that calculator, but didn't have any luck. If you find it could you put a link here. Thanks.

[Danny Cabral]

Then I found a link to a site that Danny provided, that gave me the number of crankshaft degrees the crank would turn at a certain RPM in one msec.
Danny, I tried to find the link to that calculator, but didn't have any luck. If you find it could you put a link here. Thanks.

http://www.kylesconverter.com/freque...er-millisecond (RPM To Degrees Per Millisecond Conversion)
Yes, in order to optimize Injector End Angle tuning, larger fuel injectors are required to spray short injector pulse-width
durations (especially at higher RPM). This makes it possible to fit the fuel injection event in the programmed time frame.

This post explains the Injector End Angle table that works very well for me: LINK.
http://forums.holley.com/showthread....0207#post80207 (Related IEA Forum Post)

[TBART1970]

For me it was 21° ATDC. Then I looked at some datalogs I had of it idling, and found my IPW at idle. Then I found a link to a site that Danny provided, that gave me the number of crankshaft degrees the crank would turn at a certain RPM in one msec. Get this number and multiply it by your IPW and you know how many crankshaft degrees your injector is open at idle. Then I positioned my IEA, so the fuel would start to spray just after the exhaust valve closed. This gave me a very stable AFR at idle with no off idle issues.

I'm not sure how to ask this? If you know the closing point, what does the IPW number do for you? Is there some math that's missing?

[81 TransAm]

If you know that at 800 RPM (by using the link to the calculator) the crank moves 4.8 degrees/msec and your idle IPW is 3.5 msec then you can multiply 3.5 x 4.8 and that will be how long the injector is open in crankshaft degrees. In the above illustration, that would be 16.8°. Then if the exhaust valve closes at 21° ATDC, you would add 21° to 16.8°. That would be 37.8°. So you want the injector to start to spray at 21° ATDC and stop at 37.8° ATDC. So in Holley terms you would want an IEA of -142.2° to make this happen.

[TBART1970]

OK, makes sense now. Thanks.

[lockjaw-express]

IEA Radical Cam - Issues



I have a 448 BB Mopar Wedge, and I entered -120° for the IEA without the table, and it made a very positive change. It gained 200 RPM, AFR went from 13.9 to 14.6, and vacuum went up 2 kPa. I built an IEA table, but could use some help with the table, and idle areas. The engine was 680 HP on the engine Dyno at 6400 RPM with a carb, originally. I have a stumble and goes very rich on take off. It's a stick car with a 3:08 first gear and a 4:30 rear gear. I have Holley CNP Smart Coils, 36 tooth crank trigger sensor, and a cam sync sensor. Thank you, Mark.

[81 TransAm]

Screenshots are not much help. We need datalogs and your Global File.

[allan5oh]

That's a really neat way of doing it Mr. 81 TransAm. No doubt you had great results. It really seems like the larger injectors or cam overlap you have the more important tuning IEA becomes for idle, off idle, and low load/RPM situations.

Just one thought. I'm assuming you tuned the idle IEA using IPW hot idle in gear. Would this not mean it isn't optimal for cold starts? The injector PW would be larger therefore it would be injecting before the exhaust valve closes. But at what point are you splitting hairs? Thanks for sharing what you did, I really appreciate it.

[81 TransAm]

Just one thought. I'm assuming you tuned the idle IEA using IPW hot idle in gear. Would this not mean it isn't optimal for cold starts? The injector PW would be larger therefore it would be injecting before the exhaust valve closes. But at what point are you splitting hairs? Thanks for sharing what you did, I really appreciate it.

Yes, I tuned it when it was hot. When cold I run it a little richer until it warms up, and it seems to be happy this way.

[allan5oh]

It would be nice if you could offset the IEA as it's warming up, to keep the injection event start after the exhaust valve closes due to larger PW.

Anyone have any idea of the distance between fuel injector and valve on a typical SBF? Super Victor EFI intake.

Cam closes exhaust at 9° ATDC which is -171°.
Overlap of 12°.
INJ PW is 2.11 msec at idle.
At 850 RPM that is 10.761°.
So that to me is -160.2°.

This is ignoring the time it takes for the fuel to travel down the port (SBF Super Victor EFI). <---- The S2H "cancel fuel flow map" method.
So to me this makes sense as to the optimal setting at idle and low RPM/loads.
The third consideration is getting all fuel finished by BDC. This is the S2H method offsetting everything so idle area is 0. Of course this is at higher loads.

You know what would be really neat? Making a math channel for this.

[allan5oh]

Yes, I tuned it when it was hot. When cold I run it a little richer until it warms up, and it seems to be happy this way.

One way is do an Advanced 2D Table and an IEA Offset. X is RPM Y is PW. Make the first row your idle PW and 0 across. Then make the rows above that the difference in crank degrees (positive) between that PW and your idle PW. Doing it this way would keep your PW beginning always right at exhaust close regardless of how wide the PW is (cold start or AE). Of course above a certain RPM you DON'T want to do this. Just keep those columns 0.

You know what would be really nice? If Holley had a "start PW at exhaust lobe close" check mark on the IEA table. That would eliminate doing work on two 2D Tables. Also have a spot for "until xxxxxx RPM" where it just switches back to the table. Another option is why not have the IEA table Y axis as pulse width instead of MAP?

[allan5oh]

IEA Tuning: MAP vs IPW

Does it not make a heck of a lot more sense to use IPW (injector pulse width) as the y axis on the IEA table? The MAP sensor always lags what is actually happening in the port. If it didn't there would be no need for TPS or MAP AE. However IPW does account for AE! Let me give you an example:
- Engine has an exhaust valve close of 10° ATDC.
- Tuner has determined he wants to avoid injecting fuel while the exhaust valve is open at all costs lower in the power band to avoid fuel during overlap. See this thread: https://forums.holley.com/showthread...d-Angle-Tuning
- 1.9 msec IPW correlates to 9.7 crank degrees at idle.

So to inject at the end of overlap ignoring port velocity:
Valve closes at -170 (Holley IEA table reference)
IEA set at -160 due to 10° PW

Now what happens when the throttle is pushed? TPS AE kicks in and adds fuel but the MAP sensor hasn't responded. We could easily have 10° to 20° of injection off idle or even more during overlap. A Y axis of IPW fixes all of this. On a well tuned engine (base fuel and AE) the IPW is a better indication of what is going on in the ports during transients. Steady state does not matter because the MAP sensor always catches up.

A question. At the same rpm say 5000. If VE increases this also means port velocity increases by the same amount correct?
Also, why doesn't the IEA calculator have port cross section? I would think this is vital for calculations.

[81 TransAm]

Like everything about tuning, compromises have to be made. TPS EA does add fuel but my fuel table is tune pretty good and I use very little TPS AE. Your idea does sound interesting, I may try it out. I have not found a way to change the X or Y axis.

[81 TransAm]

After doing some testing using an Advanced 2D Table for IEA Offset I can say it seems to work very well. I always had a very stable AFR trace at cruise. Now it is even a little better. It flatlines at my target of 14.7 AFR. It can sit there for 10 to 30 sec on a flat road before it blips a little then back to flatline. On my display I put IEA & IPW side-by-side so I could see the IEA change as the IPW increased as load increased. On my table, I didn't worry about an IPW over 10 ms and anything over 3000 RPM. All I wanted over these settings was to get the fuel in the cylinder before the intake valve closed. This is what I ended up with.
Allan5oh, very good suggestion, it work well for me and I'm going to keep doing it this way.
EDIT: Too hard to see screenshot, so I added my Global File in case anyone wants to see it. I'm using V5.

[allan5oh]

Thanks for following up. What about tip-in off idle and cruise? I think that's where the biggest gain is optimizing IEA. Did you notice warmup was a bit better? You might be able to pull some coolant enrichment out. A datalog of tip-in would be nice too. It seems like there's always a lean blip (slight misfire).

Another thing you could do is have two Advanced Tables and have them overlap on the X axis. I haven't tried it yet. More resolution.

There's now three things they can improve with their IEA scheme. A lot of tuning issues can be related to sub-optimal IEA settings. I wish Mr. S2H would chime in. He doesn't want to give away all his secrets though.