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http://forum.nistune...&t=2135&p=15305

I asked the nistune guys, from their bench testing this is what Pete has seen.

All SR20DET (except RNN14) and 16-bit Z32 are batch fire at all times.

All ECU's go batch fire if they go into limp-home mode.

CA18DET is sequential at low loads and goes batch fire at high loads.

All others are sequential all the time.

Edited by Rolls

Pete replied with:

Yeah, over on SAU they think a lot of things...

It's been awhile since I took a detailed look but I'm pretty sure they use injector driver chips with 4 drivers each. So a 6 would use 4 elements from one and 2 from the other.

There's sure to be somebody who knows the ECU circuitry better than me but I'm pretty sure that was the deal.

I can definitely tell you the RB20/VG30 is sequential cos I've got 6 injectors hooked up to my test rig and you can distinctly tell that they're firing sequentially.

PL

edit: I think it is the type 1 board that has only two injector drivers, eg the redtop ECU in the R31s

Edited by Rolls

I noticed you specified the 16 bit z32 from what I have read the 16 bit has issues with Nistune but the older 8 bit is fine (I read that on the Nistune forums of he wants to take another shot at sau) so im assuming the 8 bit is batch fire?

Injector pin out between the rb20 and rb25 ecu's are slightly different, 2 pins are swapped

I was advised by Nistune there is no need to swap then as the injectors are fired in 2 batches of 3. The 2 injectors were on the same batch.

I will be pretty pissed if this is not the case as this would probably be the cause of my car constantly running like crap.

Will wait for Pete to reply. If he has a bench setup it is VERY easy to tell if it is fully sequential. Another test is to pull your cas out and spin it by hand, can you hear the injectors fire one by one, or in banks?

haha too late for me, sick and tired of my car running like crap so I finally took the plunge and bought an adaptronic plug in ecu.

Not a bad word against the Nistune chip i set a Z32 ecu up in my mates r33 and it ran like a stock car.

This pin swap may have fixed my constant misfire at idle and low loads.(Issue was not there with stock ecu)

Pete is going to pull apart an ECU and get to the bottom of it.

Curious what the case is, I am not sure if I am running a rb20 or rb25 injector loom so will be curious about this pin swap as well as I also have an idle misfire.

I understand that...but if you have to swap ecu pins etc...It just seems like there are a lot of hassles with poor running, missfiring etc

whether that is the people fitting it boards or whether swapping the pins and potentially firing an injector into an open intake valve which is creating the issues is a whole other matter.

I understand that...but if you have to swap ecu pins etc...It just seems like there are a lot of hassles with poor running, missfiring etc

whether that is the people fitting it boards or whether swapping the pins and potentially firing an injector into an open intake valve which is creating the issues is a whole other matter.

Which is what is being investigated now. The pin swap is only relevant to RB25 owners running RB20 ECUs and it does (or at least did) say to do it in the manual, it is only relevant if it is fully sequential though.

Time will tell. Not really sure what you are getting at.

Edited by Rolls

Its kinda hard to explain what Im getting at lol....if the 25ECU is batch fire and using a Sequential ecu, and have to swap a pin so all 6 injectors fire instead of 5 or 4 or what ever the case may be, is that the wiring may not quite be right.

As an example on the EF falcon 4L they run batch injection and wasted spark...runs perfectly fine as standard as the intake valves are closed when the injector and wasted spark fires on the exhaust stroke...when you fit larger cams with more over lap the valve is slightly open and fresh fuel gets into the chamber + the wasted spark was igniting the fuel as it entered the chamber with the intake valve open, only happened at low load/idle though, but the cars never ran right even at WOT

Only option was to run a funky cam profile or fit an ECU with 6 injector drivers.

Thats my basis for thinking what I'm thinking about the funny little missfire that some guys get.

I maybe completely wrong in this instance, especially with the RBs running coil on plug...but it maybe fuel is being squirted at the wrong time into the chamber on 1 cylinder.

Not that its really important as most owners dont report problems....It could also be that there are a couple of different types of ECU's...I know RB25's have 2 types maybe Silvertop RB20s are the same??

They run fully sequential ignition so that wouldn't happen. However mixing the injectors up would mean one ran slightly leaner and one slightly richer as some of the fuel would pool on the valve vs less on the other cylinder.

So if this has been mixed up then it would quite possibly still mean worse idle/low load running as 2 cylinders would be running slightly out of sync AFR wise.

Yeah :)

Or its electrical interference half firing an injector at some random time or setting off one of the coils...could be anything really

An Oscilloscope would come in handy at times like this lol

Are RB20 and RB25 CAS' the same internally?

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