Other than an EU or JWT, the 4th gens have no real way of getting an upgraded ECU. Both the EU and JWT are quite pricey to say the least and I was just told that you can effectively advance the timing on a 4th gen by using an adjustable fuel pressure regulator and an air fuel controller (ie. V-AFC, S-AFC). Has anyone done this in the past and what are your results? I would like the benefits of a tuned ECU without the raised rev limiter, even though a MEVI will be going in shortly.

 

emanage blue, dandymax just advanced timing on knight yyz's car with it and it seemed to make a definite difference at the track.

why don't you want the raised limiter though? that is the biggest single difference you can make for an MEVI'd car.

 

I think knight is in a 5th gen..

 

It doesn't matter since EB's are universal.

 

o rly

link to thread?

 

http://forums.maxima.org/showpost.ph...2&postcount=48
http://forums.maxima.org/showthread.php?t=400490&page=2

 

http://forums.maxima.org/showthread.php?t=400490&page=2

We should probably start a new thread about this in All-Motor...

Edit: darnit Nmex you're too fast.

 

Very nice, we should make a new thread. Used EB's go for 125ish!

 

I second this motion.... If only we could extend the rev limiter with it as well (sighh....)

Perhaps some1 needs to relook into it and rig something to make it work?

 

I had dug into this problem a while back, and I think that some minor-league electronics could do the job.

When fuel-cut happens, the electrical pulse going to each injector becomes much shorter, cutting back the fuel going through each injector about 90%.

With a handful of parts, it's possible to sense the shorter pulse coming from the ECU and substitute a pulse of the same duration going to the injector. When fuel-cut is done ( the ECU pulse goes back to the longer pulse) then the ECU is back in control of the injectors.

The ECU ignition map is good for at least 8000 RPMs - so if the injector pulses could be restored, you could happily rev to 8000 at the strip. Once.
..

 

You're speaking of some sort of signal amplification device here. Working along the same lines as our ignition boosters (12v input, 15v-24v selectable output). But instead of voltage, it has to boost the pulse width.

You're saying that fuel cut doesnt COMPLETELY shut power off from the injectors, it just reduces it to ALMOST nothing. Hmmmm..

, DandyMax Mr. E-Manage guru, do you have any input on this hypothesis? How viable could this be?

For the stuff that Im doing Im lookin to redline around 7500. If something could be rigged for this to work, using an EB... OMG we'd have some serious cars getting done (probably along the same lines as when it was figured out the 3.5 can fit in the A32 )

 

Welcome to like 2-3 years ago mang...

 

Well sir ESCUUUUUUUUSE ME for having a bible and the book "The Secret" (everybody should read it btw) next to my bed.... and not a hard cover, laminated, original 1995 paper copy of the FSM , LOL I kid I kid. Hey I just started learning about the car's electrical stuff recently. 2-3yrs ago ANYTHING electrical I'd ask streetz or s0ber to do it for me, lol. I avoided electrical stuff like the plague lol

 

Some IC logic would be required - I did one circuit design a while back, but never turned it into hardware. My recollection is that it wasn't too hard......

Somewhere in my '99 FSM it mentions how fuel-cut works, I believe. Seems like Dandy and I had a short conversation on the fuel-cut topic - I think he first brought my attention to how it works.

I haven't looked this up again, yet - just speaking from memory. Check the FSM for a sanity check. EDIT: EC fuel-cut pg23-25 in the '99 FSM. no mention of pulse duration there.

Without looking up my notes, it seemed doable. You would open up each injector hot wire (other is ground) and feed both sides of each wire into a magic box. 14 wires total needed - one for battery, one for ground (-) and the 6 pairs of IN-OUT wires for each injector. During WOT the injector timing is run from a map, so by using an oscilloscope you can measure the exact duration of the ECU injector pulses at 6500 RPMs. That will be the fall-back pulse duration when fuel-cut hits - no interruption of fuel at 6550 !!

EDIT: I got that backwards - all injectors go to the switched battery bus, then through the injector coil, then are individually switched to ground by the ECU. Extending the pulse would require re-routing just the ECU-side injector wire through the new circuits......

Is this important ?? I never went further because I was poking an old junkyard-dog 3.0 and the idea of spinning it to 7000+ didn't seem too bright.

But....

 

I figure you would know if my fuzzy memory is right or wrong about what happens during fuel cut ???

 

Use a SPST(or would it be double throw?) relay? Simple switch device, but I think relays switch on voltage, not pulse width. A timing IC as used in the rpm switch I am building would work. Theyre cheap at the Shack for I think $7. That, and a few pots, caps, etc...and it would be feasible. Anyone want to get together and work on this? Ive got a decent amount of circuitry experience and hands on stuff, just dont have all the time to build/test it myself(not to mention, no EB).

 

Although, would you even need the EB to use this? Sure, you wouldn't be able to tune up top, but you could still be able to up the rev limiter since it's engine management 'agnostic'.

 

I think you would still need it as a "glorified" RPM switch since you have to ramp in a lot of fuel right before rev cut then adjust it as the RPMs increase past the cut point otherwise you'll be stuck at the one fuel setting the entire way to your new limit.
Is there another RPM switch alternative that could output to the fuel adjustment device at more than one set point?

 

Grey you asked me about the rev limiter and how it works in some other thread somewhere, I can't remember which one now, searching would probably find it though. The FSM won't tell you what it does, I discovered it through the EU datalogger. At some point I'll play with knight's EB a bit more and see what it can (or can't) do with the rev limit (if he lets me.. lol). At this point I don't think it will work, but there's something I want to try for myself.

 

Dandy, I found that thread: http://forums.maxima.org/showthread....l+cut+injector

You made some comments about how you measured the injector pulses getting much shorter which causes the fuel cut. You did some good research into the fuel flow here. The thread did match my fuzzy memory - for a change - and explains why I bought an assortment of parts last fall.

This might be do-able - but I'm pretty sure I don't want to do it for others. This would take a lot of time to debug, and since I'm getting the 3.5 installed next week, I will be busy with that.

 

No, not that I know of. It would reuire software of some sort, thus memory unites, etc...Atleast, the most efficient way would be that. I guess an array of potentiometers would possibly work, but that would be a LOT of tuning...

 

If the EB fuel is the same as the EU fuel, I am sure it will work. But Dandy knows much more about this than I

 

There are differences... but I'm still going to try it on the EB if the test car's owner is up for it...

 

Good info guys....that would be a really involved and even better alternative to the JWT. But what about an AFPR and VAFC? I plan on using a VAFC to activate the MEVI anyways, so will the AFPR really make a big difference? I am completely new to this....

 

people have datalogged the timing change with SAFC... i30tMikeD for one. search on it. i know i saw the thread a few months ago.

 

Forgot to update this, I did try the rev limit extend using the EB additional injection map (but not the sub-injectors, that has yet to be tried AFAIK) but as I expected, using that method doesn't work:

-The EU allows you to directly specify the exact amount of additional fuel you want added to the factory signal, ie the pulsewidth. However, the EB does not. Instead you can only specify the additional duty cycle you'd like as a percentage of the factory duty cycle, so even if you input the maximum percentage (100%), it's only 100% of whatever you already had, not 100% absolute duty cycle (ie referenced to rpm).

-As an example for those who may find numbers easier, let's say that post-rev cut at 6600 rpm the ECU only pulses the injectors for 1.8 ms. At 6600 rpm this corresponds to a DC of about 10%. Well with the EU, if you added 12 ms at that point you'd actually get a total pulsewidth of 13.8 ms (12+1.8=13.8), which corresponds to a DC of about 76%.

Now consider the EB, you know you'd need to get to 76%, and you only had 10%, but if you enter 66% (76-10=66), it's a percentage, so you'll only get an additional 66% OF 10% = 6.6%, for a total DC of 16.6% - not nearly enough. And even if you crank the number up to the max at 100%, you're still only doubling the original 10% for a total of 20%. And that's why it doesn't work.

 

Just to give a heads up to everyone... Calum from Calumsult (some of your SR20 heads may be familiar with him) is working on converting my stock A32 ECU to a realtime, FULLY programmable/adjustable, ECU. A friend of mine mentioned to me that he had his ECU converted and he put in the word that I was wanting something like this. Calum told me that he is familiar with JWT programs as well as Technosquares and if they were able to do it, he, more than likely can do it.

If it all goes through, we wont have to deal with additional harnesses, write ups on how to make the EU or EB work... all we have to do is plug the USB cable that will be connected to the ECU to a laptop and tune!!

This is still in the process and I havent heard from Calum yet to see where he is at with this, but at the same time, I dont want to rush him...
I will keep everyone posted with this.

 

Perhaps it is too early to ask this, but I'm assuming you will need some separate cable/wiring/plug/adapter for a WBO2, correct?

 

Assuming that it will be done the same way the B14 ECUs are done, yup!