VH41DE nistune?

If you know what B.S. stands for you know what goes here.

Moderator: Matt

Post Reply
datsunboy
Posts: 106
Joined: Thu Mar 15, 2007 1:51 pm
Location: New Zealand

VH41DE nistune?

Post by datsunboy » Sat Sep 22, 2007 8:40 pm

would it be easy to modify a version of nistune hardware to run in a VH41DE ECU?
the early ECUs use the same EPROM style as CA18s, but the later ones were similar to SR20s

datsunboy
Posts: 106
Joined: Thu Mar 15, 2007 1:51 pm
Location: New Zealand

Post by datsunboy » Wed Sep 26, 2007 7:33 am

anyone?

Matt
Site Admin
Posts: 8279
Joined: Sun Jan 29, 2006 1:45 am
Location: Adelaide, Australia
Contact:

Post by Matt » Wed Sep 26, 2007 10:20 am

Most likely can do it... if not can use an emulator at least

I would need the ROM image and a picture of the inside of the ECU to start with. Send those through and I can have a quick look

GZ@hybridka
Posts: 112
Joined: Wed May 03, 2006 5:51 pm
Location: Id, USA

Post by GZ@hybridka » Wed Sep 26, 2007 1:14 pm

If they are anything like the VH45DE, the 8 bit and 16 bit versions are very similar to Z32 VG30de(TT), both the board style/layout and code arrangement.

Matt
Site Admin
Posts: 8279
Joined: Sun Jan 29, 2006 1:45 am
Location: Adelaide, Australia
Contact:

Post by Matt » Wed Sep 26, 2007 4:58 pm

8 bit VH45DE fills the entire 32K ROM chip, theres no room to fit my Type 2 firmware so we cant do a board for those VH41 might be the same ..

16 bit would be a Type 3 board. These have the same configuration as S14

Note that the S14/Z32 ECU connector plugs are exactly the same also. I can run Z32 ROMs on a S14 and runs on the bench with consult except no injection

datsunboy
Posts: 106
Joined: Thu Mar 15, 2007 1:51 pm
Location: New Zealand

Post by datsunboy » Thu Sep 27, 2007 6:37 am

might just be easier to use a emulator and live edit then?
theres no way to run a V8 off 1 or 2 4cyl ECUs is there?
since the spark timing wouldnt line up?

Matt
Site Admin
Posts: 8279
Joined: Sun Jan 29, 2006 1:45 am
Location: Adelaide, Australia
Contact:

Post by Matt » Thu Sep 27, 2007 11:10 am

Can you shoot me through the ROM image for that vehicle? You should be able to use emulation with nistune

GZ@hybridka
Posts: 112
Joined: Wed May 03, 2006 5:51 pm
Location: Id, USA

Post by GZ@hybridka » Thu Sep 27, 2007 12:18 pm

Though its not worth the effort as there is plenty that can be done with the original V8 ecu (emulator + consult at a minimum), theoretically you could setup a 4cyl ecu to run the V8.

You would need to swap in the 4cyl cas disk, and reconfigure the fuel and ignition outputs to batch injection and wasted spark ignition.

Assuming it has coil on plug, you could use a ca18 or sr20det ecu without too much effort. Just rewire the coils and figure out which sort of injection batch scheme you want to do. If you want 2 batches instead of 4 you could use some diodes to join the signal of 2 injector outputs. If you wanted to use 4 batches you would have to figure out the injection timing. Im sure its been done before on some EFI system as it is common to run them with only 2 batches.

You would need to use all 4 ignition outputs and "batch" them up as well, wasted spark fashion.

As an example, motorcraft edis-8 uses wasted spark ignition using 4 coils , here is some documentation:

"On 4 cylinder engines pins 10 and 12 are used for the 2 coils. On 6 cylinder engines pins 10, 11, and 12 are used for the 3 coils. On 8 cylinder engines pins 8, 9, 11, and 12 are used for the 4 coils.

On all engines the complementary coils are connected to the cylinders that are 180 degrees apart in the firing order.

Example: Ford firing order for V8 engines is 1-3-7-2-6-5-4-8. You would connect cylinders 1 and 6 to the same coil, 3 and 5, 7 and 4, and 2 and 8. Follow the same approach on 6 and 4 cylinder engines."


You could do the exact same thing when using the 4cyl nissan ecu on the v8, but instead of using 4 coils and batching the output side, you would be using 8 coils and batching up the input side.

EDIT: I guess I shouldnt say exact same thing, the nissan v8 might have a different firing order, and the corresponding 4cyl channel would depend on how you have setup the 4cyl cas, the same idea anyways.

datsunboy
Posts: 106
Joined: Thu Mar 15, 2007 1:51 pm
Location: New Zealand

Post by datsunboy » Thu Sep 27, 2007 1:07 pm

very interesting!
We had an awesome idea at the time, of running it on 2 seperate CA18 ECU's
then maybe having it so that you could switch one ECU off, and that would stop fuel and spark to 4cyl....so effectively having a V8 that you can turn 4cyl off at your leisure. 8) .
then I went home and thought about it, and thought maybe it wouldnt work since V8's are timed 120deg apart instead of 90deg apart like a 4cyl.

even just running it off 1 CA18 ECU would be a huge advantage, as I have a CA18 Nistune board.

do you think this could work? ( the 2 CA18 ECU idea ).

I dont have a ROM for it yet sorry matt, the engine hasnt arrived yet

GZ@hybridka
Posts: 112
Joined: Wed May 03, 2006 5:51 pm
Location: Id, USA

Post by GZ@hybridka » Thu Sep 27, 2007 1:55 pm

There is a large flaw in that my theory above,

The 4cyl CAS disk would have to spin a 2x cam speed (or crank speed) for that to work... :?

And, the maximum RPM the ecu could handle with that configuration would be 6000rpm, the CAS will be spinning at twice the speed throwing all ecu calculations off (it will think its at 12000rpm).

The 4cyl ecu will not operate with the 8cyl CAS disk.

So, bunk theory, 4cyl nissan ecu on a v8 is a no-go.

datsunboy
Posts: 106
Joined: Thu Mar 15, 2007 1:51 pm
Location: New Zealand

Post by datsunboy » Wed Oct 03, 2007 10:22 am

are you sure about that?
that really sucks lol
is there anyway I could get the CAS disc CNC machined to make it work then? ( I know someone who would do it free lol )

GZ@hybridka
Posts: 112
Joined: Wed May 03, 2006 5:51 pm
Location: Id, USA

Post by GZ@hybridka » Wed Oct 03, 2007 2:17 pm

You need 4 ignition events per revolution on the V8, the 4cyl CAS spinning at cam speed only provides 2 ignition events per revolution.

You still need the 4 events per revolution with wasted spark, the only difference between wasted spark and individual coil fire (cop) is that with wasted spark, only one sync per crank revolution is required, unlike COP which requires sync every 2 crank revolutions.

Using the 4cyl CAS on the V8 would provide the sync every 2 crank revolutions (or one cam revolution), the problem is there are only 4 ignition events.

So if you sped the 4cyl sensor disk up to 2x the speed (crank speed) it would work for wasted spark, giving 8 ignition events for each 2 crank revolutions, and one sync per revolution. The problem is that this is not easily feasible and the ecu will be interpreting twice the RPM.

You cant use a 8cyl CAS disk on a 4cyl ecu because the count of 1 degree slots is different between each of the cylinder increment slots. On the 4cyl there is roughly 90 or so slots between each cylinder increment slot, and the 8cyl would probably be about 45 slots.

The counters and timers of the various embedded controllers inside the ecu will not interpret the CAS properly, doubts are that it would even fire a single event.

You could recode the ecu to work with the alternative CAS, but that would be far too much effort.

Stick with a V8 ecu, vh41 or 45. Options are endless.

Post Reply