Hi

Does somebody know how works the injection advanced map for the AEM EMS 1052 v1?
For example the startup calibration injection advance map is set to 11.3 for all load breakpoints at 1000rpm.
Does it mean the injector firing is set 11.3 before TDC ?

Thanks for any help.

 

I read again some topics on the AEM forum and maybe I have a better idea on how it works now.
When datalogging the "Fuel Inj#1 open" parameter, it gives tooth 11 when the Inj advance map is set to "0". As tooth 12 is TDC and one tooth is 30 degrees (360/12), I understand the injector 1 is fired 30 degrees before TDC.

Could someone confirm I am right?

Thanks

 

injection advance works just like ignition advance. Its all based on the injector phasing and how thats all setup.

Really the only thing as far as injector timing that will make any noticeable difference is to play around w/the injector phase to increase throttle response.

I have spent A LOT of time (dayyyyys on the dyno) tuning injector advance with large and small injectors and the fact is that it really doesn't matter. under about 20% duty cycle you can gain some throttle response and economy (read.. some.. not very much, hardly noticeable at all, ie. not worth the time). past 20% duty you are pretty much always going to be spraying fuel on the back of the intake valve.

 

Thank you for sharing your experience.
You are right and I don't want to waste too much time to play with injector phasing.
But I like to know how things work and I would like to reduce as much as possible emissions for my street use. I feel noticeable improvment in drivability too on low cams by playing with the injector advance map.

 

I would like to share some more thoughts about the fuel injector timing.

My engine setup is F23 Endyn long block with Hytech cams and Siemens 630cc fuel injectors. With the AEM startup injection advance map, there was lot of carbon deposite inside the exhaust system and a very strong fuel smell from the engine oil as well (dilution).
After some calculation, I found for the main part of the map the fuel injectors start and finish to spray before the inlet valves are opened!
In fact, with the 630cc injectors and the Hytech cams, for 85% of the fuel map it is possible to spray all the fuel needed while the inlet valves are opened. It is impossible to do it only on high cams after 5500 rpm.
For all other cells, the startup calibration starts to spray a way too early for my setup.

Maybe there is no peak power to gain by fine tuning the fuel injection advance map as the maximum power is obtained where the fuel injectors need to be opened longer than the inlet cams duration. But I think the engine reliability could be hurt if one doesn't take care about it for a street engine. Then, I am surprised there is no more talk about the fuel injectors timing.

 

back in the day we spent ALOT of time on the dyno with a mostly stock h22 that had 750cc injectors. We saw similar "issues", then "fixed" them. Then we went back to a stock ish (330cc) injector. We still had plenty of head room, power and drivability were no different and the injector advance mattered even less.

On cars with 1000-1600cc injectors the timing does need to be tweaked as it affects throttle response a pretty good amount. Usually all thats needed is to change the injector phase. Its pretty rare to need to mess w/the actual injector timing map. And since you never know exactly how long it takes for the fuel to move from the injector to the cylinder there is no exact science, just feel. I usually move the injector phase around a few teeth up and down, see where throttle response is best and let it roll.

Whats the max duty you are seeing?

 

I agree it is not easy to know what is the mixture velocity. But I doubt it is the best setting when stopping to spray before the inlet valves are opened

For example my fuel map cell 4000rpm/59kpa is 3.08 mS. It means the injector is opened 74 crank degree. For that cell, the original injector timing is 100 degree BTDC. On low cam the inlet valves timing is TDC @ 0.04". Then the injector stop to spray before the valves are opened. I think the injector timing is at least two teeth too early.

My max duty is 60%.