Zaphod

Hi,

as we have measured/found pretty different settings for these injectors on msextra -

460cc RX-7 red top (high imp)

I thought I make a separate thread:

Before I went sequential I used the 2squirts/4squirts method to get an equal AFR and found a dead time of 1.185ms

Techsalvager uses a dead time of 0.75ms

Here in this old adaptronic thread I found a complete chart for dead times for these injectors.
https://www.miataturbo.net/showthrea...time+injectors

Is the usage of these dead times different between Adaptronic and Megasquirt? Anyone else has got working settings for these injectors?

Thanks and please discuss!

Braineack

iTrader: (62)

i use 1.2 @ 13.4v

Zaphod

Well one of the points why I did this thread is that all the informations I found online about the RX7 injectors were about 550cc or low impedance injectors.

@Braineack - your 1.2 are very close to the 1.185 I got - but I must admit that my car runs at about 14.4 volts and the test I did was at this voltage...

Braineack

iTrader: (62)

that's the reference value that ms3 uses. i have a correction curve as well.

Zaphod

Please post

Techsalvager

There is plenty of posts and other data out there that point to the injector lag time of 13v being around .75ms~ for the 460 and 550 high imp injectors.
when you have improper lag times, esp with systems like ms2extra a change in voltage can easily swing fueling up or down.
both my maf and speed density setups show these swings with voltage changes.

On my maf setup I couldn't run leaner then .78 ~ .82 lambda at normal ~14v, ---- i had maf grams a second at .33g\s which isn't even right.
changing to .75ms at 13.2v put my maf g\s around 2.4-2.6 range which is where it should be for the engine size and load. and idle afr at 1 lambda

Zaphod

I always found something like this:
http://www.rx7club.com/showthread.php?t=869605

But I am going to try out your proposed 0.75ms with the curve from the older adaptronic thread.

Again my question - I know there are differences in the understanding of the dead times - are there differences between the Adaptronic and Megasquirt firmware for the dead times calculation?

Techsalvager

responding back to this, couple days ago I blew off a charge pipe, of course I'm running a maf based system so we know what can happen.
Anyways I decided its probably a good time to redo my SD setup.
reattached the charge pipe.

I filled the whole table up with 59 in the main ve table with SD running fuel and spark.
Amazed at how well it idled and drove with a table full of 59s.
this is with injector dead time at .75ms

Techsalvager

http://www.2shared.com/file/H7EyKv5y...07_182032.html

datalog of recent SD tune I was working, watch GVE and Lambda vs RPM and MAP

Zaphod

I tried it today and the car runs pretty darn cool. Thanks!

(Although I am loosing sync at 4200 rpm... but that is another story)

Zaphod

O.K. just to confirm, the 0.75ms work like a charm, the VEtable is nearly flat in the non-boost area. And this is the first time that my idle VEs are matching the neighboring cells...

Oni

iTrader: (1)

Sweet ill try this out tomorrow, any chance you would mind SS the related screen? I messed with some low imp injectors and want to be sure im all set correctly.

Cheers
Scott

Zaphod

There you go...

Techsalvager

are you using the rx7 460's? or the low imp rx7 injectors?
low imp rx7 injectors used correctly dead time is suppose to be around .50\.55ms

Braineack

iTrader: (62)

mine stalls if i put in lower than 1.1ms.

Techsalvager

increase VE cells of course

Braineack

iTrader: (62)

doesnt even matter. if i set it to 1.0 car stalls no matter what the AFR is.

Techsalvager

datalog? PW? ve area at idle?

Braineack

iTrader: (62)

its not worth my time to discuss it any further...ive run the above for over two years.

rb26dett

Dead time settings are totally dependent upon your driver setup, and, even the gauge of your wiring. They're something that should be measured with a comparable setup to what you will run on the actual car.

As techsalvager says, dead time settings being correct is absolutely critical to an easy tune. As he also points out, you can mask incorrect settings with other adjustments. Few take the time to properly setup this parameter.