Spaceball 1

iTrader: (8)

I have some questions about the injector timing function. Where should i be about with the evo with 272 cams. I understand if you do not want to give me a exact calibration. I just want help on how to figure it out, maybe a math equation for runnner lenght, cams, rpm, and injectors?

Currently im at 0 idle and scaled to about 100 at about 6k. Car runs great and pulls strong, but the manual speaks about been at -180 at idle and starting from there.

Also have a question about Microbit/sec in the fueling. I dont understand what it is and manual doesnt speak about it. What shoud that be set to?

Thanks

EVO8_PR

iTrader: (5)

Microbit/sec is the value by which the raw fuel table is multiplied in order to obtain the injector pulsewidth. The smaller the value, the lesser maximum pulsewidth but more fine tuning would be available since the jump between "steps" in fuel would be smaller. The value on my .cal is 15 uSec which gives a max of 3.83ms of injection pulsewidth(.015 microbit/sec x 255 raw value= 3.825 pulsewidth).
I know it's a small value but for my 1600cc injectors it's more than enough.

Spaceball 1

iTrader: (8)

Thanks

Any help on the injector timing?

Ackerson

I think you're referring to injector phasing. If that's the case this thread was helpful in my situation: http://forum.aempower.com/forum/index.php?topic=17177.0

kjewer1

iTrader: (4)

I found the threads on the AEM forums a bit cryptic. I had to really wrack my brain for a few hours over a pizza staring at the laptp to get my head around this enough to make meaningful changes. Ultimately I came up with a spreadsheet that figures it all out for me for each cell. I'm still doing some testing, so I don't want to offer it to anyone yet however. But the changes I hve made so far have had a DRAMATIC effect on both power (5mph gain, almost back to where I was with DSMlink) and driveability, especially very low speed driveability. The motor is so much smoother too, it's unreal. A couple times I thought the motor was stalling at stop signs again, but it was still running.

It occurred to me after some thinking that due to my relatively low duty cycles at WOT with the 950s (~52%) compared to the intake valve only being open for ~40% of the cycle, I could theoretically be spraying 100% of my fuel on the backside of a closed valve... This is what got me thinking about injector timing.

Basically, I set the injector phase 360 degrees out of phase from the spark event like the AEM thread described in one post, and worked from that reference point. Essentially I have all longer than intake valve open time IPWs ending right before intake valve close, and all short idle and cruise IPWs starting right after exhaust valve close. I'm not sure I fully agree with these strategies yet, but what a huge improvement this made.

LetItBreath

I was trying to find some info on this as well. I find the AEM forums to be really hard to find the info you want on them. It seems like most of the threads I come across have one really long question but no one ever answers them...

My questio nfor now is shouldn't the inj adv table look like a ramp for the most part? The way my last tuner did it it looks like a plateau. Any general ideas?

kjewer1

iTrader: (4)

The way I did it with the spreadsheet I put together it's practically a mirror image of the fuel map viewed as IDC. It will roughly resemble a ramp if you do it in 2d for one load only, depending on the strategy. I chose to do it in 3d since my IDCs are so low. For poeple with typical IDCs in the 80% and up range it matters much less at WOT and you can do it 2d for a low load. If the tuner set it up for low load and starting at EVC for example, it will actually be a flat line. The idea here is that the IOT starts at the same point for all loads, and once the IOT no longer fits within the intake valve open time excess fuel is sprayed on the back of the valve after it closes and will be used on the next cycle. I chose to do the opposite at long IDCs, so it has to advance more as rpm goes up, giving the ramp look to it. So it all depends on what strategy you use.

LetItBreath

...what? Could you maybe, DEacronym that post, haha. Alex confused.

kjewer1

iTrader: (4)

Let's see.

Injector Duty Cycle
Wide Open Throttle
Exhaust Valve Close
Injector On Time

LetItBreath

haha thanks. EVC and IOT had me a little confused. Not used to dealing with these acronyms a lot.

I have 850's now and my IDC tops at about 30%. So with the low IDC, are you saying its a good idea to time the injectors to open as the exaust valve closes all over the map?

Aby@MIL.SPEC

iTrader: (161)

someone on the aem board suggested / found something that worked for his set-up........ehh, it didnt really work for me.

AS he claimed & several other people, that a ramped inj timing map reduced knock sensitivity.

My results were different, as i run 91 octane & found out some interesting stuff, but nothing earth shattering to say the least.

Here is what i did = I ran with a flat 0 map, a flat 90 & a flat 180 map. I conducted these 3 runs on the same stretch of road twice, going wot @ ~ the same revs, in the same direction on the road.

All while logging super fast internally.

the best car speed was achieved with a flat 0 map, both times! However, @ certain rpms, i had a higher knock output from my knock sensor.

So i made a inj map, based off of my car speed & knock sensor output.

1 thing i can say for sure -180 give good throttle blip response off idle than any of the above mentioned settings

0 inj timing made the rpm oscillate @ WOT between 2k-3k

1.jpg= inj timing vs rpm, 0 being base=showing me 0 had highest top speed for given time
2.jpg= is knock volt's in dot form vs rpm
3.jpg is knock volts, ign retard in bold & car speed over time, 0 inj timing reaches higher top speed.

in saying all that, i do not have a flat inj map @ 19.8 psi it's 90 between 500-3100, 45 @ 3500, 0 between 3900-5900, 30@6300, 45@6700, 0 on up.

based on the data i collected, this seemed like a good compromise in power=rpm in 3rd gear & knock voltage output.

your results may vary

enjoy

LetItBreath

correct me if i'm wrong but wouldn't there really only be one ideal injector time to fire? Aren'y you trying to time it so the fuel isn't being sprayed on a closed valve?

kjewer1

iTrader: (4)

Anything above about 40% IDC and you have no choice but to be spraying fuel when the valve is closed.

LetItBreath

oh perfect...I dont even think i hit 40% under peak boost

kjewer1

iTrader: (4)

I'm in the 50s on the stock turbo on pump gas, so if you are below 40 I'm gonna guess you're boost comped, in which case the IDC numbers are pretty meaningless. You could estimate what they are at full boost by applying the precentage change at whatever boost you run as indicated by your boost comp table.

Edit> Just ran the numbers for HKS 272s (going from memory here) and it looks like the intake valve is open for more like 32% of the cycle...