Well since I got bored I figured I would read up on the whole injector phasing thing... It seems like a hell of alot of math to get it perfect but getting it close shouldnt be too tough. I was wondering if any tuners (Shiv, Buschur, AMS, Sean Ivey, Al, etc) would care to post up thier general ideas of what a normal map would look like. It seems there are a few main variables that would change it but in our cars not too many.. the two main variables I see are:

1.) Camshaft (Most people use very similair cams so this should be about the same in most cases unless people really mess with cam gears). This would obviously change it because it needs to be known when the intake valve opens / closes to direct the fuel to reach proper atomazation.

2.) Injector size but more importantly, duty cycle needed. In such cases where people are running low duty cycles (say 60-75% compared to 90-99%) I would assume you could get away with injecting the fuel right before the valve is opening for intake charge where as the people running high injector timing will need to inject it much earlier and spray onto the back of the intake valve and keep spraying even when the valve opens... the next intake stream should easily blow enough air to atomize the fuel sitting on the valve the next time around.

Does this sound correct?

The big reason I am wondering all this and trying to figure it out is because the AEM EMS Injector phasing map seems like it is not at all correct to me. It seems that at high revs it may be injecting the fuel too late causing some of it to blow out the exhaust as wasted fuel. On top of that, at extremely high boost near the top of the stock map it flattens out really badly making it almost certainly blowing gas straight out the back of the car.

I am not sure about any of this which is why I am posting it but I am pretty sure I am correct in my theory here. I think that is what my extremely large backfires were when I capped out the map sensor at 35psi. I think I was shooting fuel straight into the exhaust causing it to explode in the header... the first few pops blew the EGT tip off (Guess I got a clipped turbo for free huh? ). If it hadnt ate the EGT sensor I could probably get a decent idea by how hot the EGTs got for that brief moment.

Anyways, if anyone has any light they could shed on this or maybe give me an idea why anyone would make a map like what AEM sends for the Evos.... how can the injector timing be (According to how they figure it out supposedly) ungodly late and only change at 2k RPMS... everything under that is injecting late, everything after that is a 180 degrees earlier. On top of that, when you get to the boost that I ran it flattens the injector timing to the same as thier idle portion of the map throughout the RPM range? This is the reason I believe at 35psi I shot gas straight into the exhaust. Unless I am missing something this is not at all the correct way of doing it.

If anyone that knows what they are doing could show us little guys some pointers it would be awesome!

 

the injector phasing on the evo base map doesnt look right in my opinion.

i set mine in a linear fashion 1500 rpm = 120' btdc to 9000 rpm = 278' btdc

also from my understanding of injector phasing, it makes the most difference during low rpm and midrange for throttle response and emissions, on the top end the events are happening so fast and the injector pulse widths are so long that it makes less of a difference.

 

Typically, the injectors are timed by the manufacturer to fire before the intake valve opens. The factory maps I've worked with were static.

With offroad and racing vehicles, the injectors can be made to fire with the intake valve open, which is purported to offer a slight power benefit (possibly by increasing atomization efficiency). The tradeoff is that squirting fuel directly into an open valve can promote washing of the cylinder, which disrupts the oil layer and tends to increase the rate of wear. Obviously, an intake cam with enough increase in duration on the front side of the lobe center will move things in this direction with no change in injector phasing.

I ran tests some years ago to determine real world differences of injector phase timing with a Ford Taurus SHO DOHC V6, but I didn't come up with anything that made enough of a difference for me to get really meticulous about it.

 

Tooners........lol

 

OK so that sounds correct with what I figured.... the only thing that I see being strange is at idle it seems the factory map sprays the fuel just before the intake stream (Havent done the math to confirm but this is my guess) and very quickly ramps up to 180 degrees earlier at around 2k then stays static. This all seems like it would work... probably not the best way to do it but I suppose it would work fine.. just not for throttle response.

The part I dont understand, where i believe the stock Evo map is incorrect is the spot starting at around 33psi to the top of the map it is back at the idle settings (Which I am assuming is trying to spray right before or right when the intake valve opens). Obviously at that boost there is no way the injector would have time to spray enough gas if the way I am reading it correctly. That is what I believe is completely wrong. I will do the math with stock cams and with the 272s and try to figure out what the degrees it is opening and closing truly are.

 

I would definately change the last 2 load rows on the phasing graph to 0 from -180. Also, a good suggestion would be to get a 5 bar map sensor if you are going to run the 35 psi on a regular basis as to give yourself some head room in the mapping. Also, I downloaded an excel spreadsheet from the AEM boards for a 3000gt that takes into account your Microsecbit, Accel fueling, etc. and calculates out an ignition phasing map. Another idea would be to look at a basemap for the DSM as it is a linear progression from 0 rpm to redline.

 

Yeah I have been reading up on it all more now. It seems to make sense and isnt as complicated as I thought.

In fact, it almost seems that really trying to screw with it except for idle and possible low-mid load ranges is worthless in most cases.

For idle, yes you could make it so the car runs perfectly fine with ungodly large injectors by ensuring they are firing right at Intake Open but other than that as long as it is close it should idle perfectly fine.

The low-mid load range I suppose you could improve throttle response but with all the other maps contributing to it, they seem they would do much more than the injector phasing (Unless you are incredibly ****).

But for most Evos at WOT, High RPM, Hi Load it seems that trying to do anything with the injector phasing is worthless because we run such high duty cycles normally you would barely be able to modify any of it to make the car do anything different without spraying gas into the exhaust.

To me it seems that injector phasing is mainly good for idle control and emmission purposes. Powerwise I think it would almost be impossible to get much about of it for two reasons. First being that by spraying half the charge on the back of the valve you would be cooling it down, helping get away from det (At least a little bit). On the other hand, by trying to spray as little on the intake valve you run into getting extremely close to spraying into the exhaust (Wasting gas, bad emmission, no gain) but on top of that, how much more atomization are you going to get when you are already running 80% duty cycle anyways?

And yes... I need the bigger map sensor. I will be retuning the car for around 30-33 psi until I get the bigger sensor. I guess I should have known that I would want to push more than that to begin with, oh well. The injectors being 780cc dont help either though. I think I am probably the only one with an A-1000 pump, -10 lines with 72 lb/min injectors

 

One of my other big problems with the 3.5 bar map sensor is I dont know if I am pushing more than that, nor do I know by how much. I got it so it just barely touches 35.12 then tapers from there to 33 or so... I would guess that is truly about 35psi but the pull before that it just flatout pegged the guage and never went under until I let off.

 

I'd like to comment but with the recent "owning" of any of my comments I can't. Sorry. Man I really wanted to help. Try one of Shiv's threads he knows it all.

David Buschur

 

Oh come on now, don't be 12yrs old.