Variable injection timing
 

I was looking at a friends map and he has variable injection timing selected and populated with values. Who here uses Injection Timing and why? Adaptronic web site suggest better throttle response and better leaner idle. Mine is horrible but I thought I just need to set Transient throttle "Predictable map" settings. Is there any benefits to using variable injection timing that anyone has found and how does one set this up?

thanks,
Ian

https://www.rx7club.com/megasquirt-f...ement-1103949/

read page 10 to 11 for some background on injection timing.

thanks for the link. Going to read up and learn. Looks difficult.
thanks again

It may be a little hard to conceptualize how the timing is calculated (start vs end timing vs duration, and how it relates to port timing).

Injection timing is hard to tune on the street. It really needs a basic inertia dyno at minimum so you can at least try adjusting at WOT. In that post I basically recommend to the OP to see if he can lean out his idle more with different end of injection timing.

I've read your link and printed out some rotary timing info. It IS beyond me! Is there any rotary tuners that tune this? Does it make a big difference on boost/drivability or just more noticeable on idle.

Generally speaking it's not a big knob for performance. You really have to determine the sensitivity of the engine to it on a case by case basis, because everybody has different port timing and injectors.

You really need an emissions analyzer to get a better idea of what's going on. HC correlates to unburned fuel from fuel sticking in the port. The CO and O2 correlate to how well the engine is mixing air and fuel.

Checking back to see if anyone has had time to mess with this over the past few years. I'm running a Universal Select 440d and using WARI. I know it doesn't matter all that much at high loads, but I'd like to smooth out the off-throttle and idle response of the motor and maybe lean it out a bit, but I don't know where to start on calculating the correct values. With the values set to 0 (or the feature disabled), when are the injectors firing? What direction does positive vs negative values move the firing? It would be nice if there was at least a paragraph about it in the user manual.

All of this is covered on the Haltech forum.

Emtron post?

Nevermind. I didn't cover it on the Emtron Support Thread. Essentially it'll change via Engine Porting though as porting a rotary is like a Cam Change on a reciprocating engine.

I tune this till the engine gets richer. 230 degrees at low rpm was my sweet spot but my injectors are way upstream.

This is something I want to mess with next time on on the Dyno. Probably October, but I'll report back what I see.

Ok, I tried +30 and -30 real quick to see what would happen, didn't make any difference with the issue I've been having but I wasn't looking closely at the AFRs. I'll try some bigger numbers. My injectors aren't close, but they aren't far away either.

Attachment 740221

I read or saw a video from adaptronic where andy tried to play with this on his rotary miata. They played with it alot and never got any measurable gains from it and set it back to zero. Think it makes a bigger difference on piston engines with the injectors close to the intake valve or maybe fd or gslse where the injectors in the center iron.

I tried some higher numbers and it started messing with transients so I went back to 0. I wasn't noticing a measurable difference at idle or off throttle so I guess whatever.