AEM EMS For VH45DE

[SSDwellah]

Okay, now that I have your attention I have always theorized about using the AEM EMS from the 300ZX on the VH45DE motor. A few days ago I compared the pinouts of the three ECUs (300ZX, 1994 VH45, AEM EMS) and made a spreadsheet with the discrepancies. It looks like there is a good overlap but some functions got swapped around. The good part is most of the discrepancies can be overcome by swapping pinouts in software but I think there are a few dedicated lines that don't match up (read: a little rewiring required). I would be interested to see a 1989-93 (early VH45DE) FSM to see if those match up too.

Anyway I am trying to find a way to host it. Putfile.com is not letting me put excel spreadsheets.

[mtcookson]

Are there not more pins on the VH ECU? I would think the VH ECU would have a few more pins for the extra cylinders (extra injector drivers for instance).

[elwesso]

I can host the file for you.

I could see it working if you could set the AEM to use batch firing instead of sequential of the injectors and coils.

[SSDwellah]

I can host the file for you.

I could see it working if you could set the AEM to use batch firing instead of sequential of the injectors and coils.

You've got mail!

Are there not more pins on the VH ECU? I would think the VH ECU would have a few more pins for the extra cylinders (extra injector drivers for instance).

Well the connectors are the same. I am not sure whether or not the VH ECU has more pins than VG ECU (that is, are more of the pin locations populated with actual contacts). It seems to me that there is just some remapping done since the Z has a few features that the VH doesn't seem to have. I own both a 93(?) JDM VH45 and 90 USDM Z32 N/A A/T ECU so I can check and see if they have different contacts populated on the ECU. In any event, all of the pins which are marked no contact on the VG ECU have contacts in the AEM EMS so this is a little bit more flexible. However it means that you probably can't (easily) use a re-flashed VG30 ecu to run a VH without some rewiring. Here's an example, there is a pin25 for wastegate solenoid. This pin is clearly not used on the N/A Z or the Q45. Also there is an AIV solenoid pin8 that is only on 90-92 Z. Etc.. Etc... So you see, not every ECU is 100% identical even across different years of the same model. I would hope something trivial like this is only a software difference, or better yet, the newer Z ECUs still send a signal out on this pin but there is no matching wire on the newer harnesses. That way the newer ECUs would be backwards compatible. On a side note, I wish JECS was more open. I would definitely buy an aftermarket tunable PnP ECU from them, but I am sure they are under NDA from Nissan. Oh well, such is life!

UPDATE: Okay I just compared the 90 USDM N/A A/T 300ZX ECU and 93(?) JDM VH45DE ECU. Both connectors are identical and completely populated. There are even pins where the FSM marks an 'X' (presumably no connection). Internally these pins are probably floating. This makes sense because it would be more economical for Nissan, or JECS who I think makes their ECUs, to just use the same connector over and over again without worrying about pin arrangements.

Modified by SSDwellah at 6:44 AM 12/31/2007
Modified by SSDwellah at 6:45 AM 12/31/2007

[elwesso]

heres the file he sent. I converted it to regular Excel so no one should have an issue opening it.

[anyotherone]

Nice. This excel file is much cleaner than the hand scribbling I did to mark the differences in pins. Good info!

[SSDwellah]

If it wasn't clear, the lines with the magenta background are known discrepancies. There are also some pins I couldn't find listed in the FSM. I would love it if someone could find out for sure what the pins are that have (?) marks on them. Also if some one has an early VH45 FSM (pre-1994) and could go through this, or tell me where to find a copy of said FSM then I would got through it as well

[tmorgan4]

There's a post on here from a while back that lists what every pin on the VH45 ECU is for.

[SSDwellah]

This is slightly off topic, but it's my topic so deal with it

Mine's makes a VH45DE ECU tune. Not to knock Wes or the Nico ECU but it would be interesting to see what they get out of this motor with just a chip.

http://www.mines-wave.com/engl...htm#3

[Q45tech]

Really only 2 parameters to change injector open time [millisecs] and ignition advance.

Dwell and injection position [in window of valve opening] won't do much.

The knock limits are so low with pump [ugh] gasoline and summer heat that you CANNOT squeeze the last 3-5% out on a dyno unless it is loaded to equal real road resistance and the temperature is elevated to summer conditions.

Pump gasoline is so variable that which refinery and which daily batch do you tune for to avoid KS activation?

Remember 1000' altitude/barometer is 3% density change and a MAF may only be accurate to ~~ 95%................why WOT is stock so very very rich to avoid a lean knock/misfire under even the worst gas or conditions.

A superaccurate electronic rail fuel pressure gauge is necessary as a drop from 43.4 to just 40 psi will change AF by 4%.

Trying to get that last 10/HP or 10 lb/ft is asking for a disaster..........even NASCAR detunes by 5%

[SSDwellah]

Really only 2 parameters to change injector open time [millisecs] and ignition advance.

Dwell and injection position [in window of valve opening] won't do much.

The knock limits are so low with pump [ugh] gasoline and summer heat that you CANNOT squeeze the last 3-5% out on a dyno unless it is loaded to equal real road resistance and the temperature is elevated to summer conditions.

Pump gasoline is so variable that which refinery and which daily batch do you tune for to avoid KS activation?

Remember 1000' altitude/barometer is 3% density change and a MAF may only be accurate to ~~ 95%................why WOT is stock so very very rich to avoid a lean knock/misfire under even the worst gas or conditions.

A superaccurate electronic rail fuel pressure gauge is necessary as a drop from 43.4 to just 40 psi will change AF by 4%.

Trying to get that last 10/HP or 10 lb/ft is asking for a disaster..........even NASCAR detunes by 5%

Hmm well I am sure they would be able to do the "run of the mill" stuff like removing the speed governor, raising the rev-limit, update k-number for bigger injectors and/or different MAFS, maybe disable some CEL/MIL codes (like A/T which I believe is 45, and EGR).

[SSDwellah]

Sorry to resurrect this thread but some new information has come to light. I have long been thinking about sourcing connectors for Nissan ECUs so I could make a plug-n-play aftermarket ECU. Well, while I haven't found Exactly that, I have found a new way to switch between factory and AEM EMS which

- Does not require cutting up your factory harness- Does not require opening your AEM and repinning/rewiring, thus it doesn't void your warranty- Allows you to switch between factory ECU and the AEM unit (or any other PnP unit) in minutes

Here is the link http://www.apexi.co.jp/product....html

The idea is to make the custom splices on this short little jumper harness. Besides just adding new peripherals such as boost control solenoids, you can make the few pin reassignments that were mentioned in the spreadsheet in my earlier posts to convert the VG30DE/VG30DETT EMS to the VH45DE engine.

Specific part numbers are here:http://www.apexi.co.jp/product...s.pdf

442-A003 seem to be the right number. Notice how virtually all the Nissan 6cyl/8cyl ECUs have the same connector, this was already pretty well known but it's a nice confirmation.

It also looks like they don't have a PowerFC unit that directly supports the VH45DE, and I don't know the extent of it's tunability so I am not sure if one can use the Z powerfc and reprogram it for 8 cylinders.

[anyotherone]

If you are concerned with hacking up your harness (IMO, I don't believe it requires enough changes to be classified as hacking up though) you could always go with one of these:

http://www.boomslang.us/extension.htm

Cheaper than the Apexi to my knowledge.

Oh, and if it helps, I have a '93 300zx TT ECU that does indeed plug right into the harness for my '93 Q45.

I would not think that the PFC would work with an 8cyl, due to the absence of a wasted spark option and only having 6 ignition drivers.

I am going to get my car running stock first, but once I get all the little kinks worked out, I am most definately running AEM EMS on my VH45.

[Carl H]

not to be a buzzkill but why bother with the aem unit when the stock unit is very capable on its own...only thing i can think of is for converting to a map setup or increased map resolution for high boost applications.in theroy it works and as you said the aem should be capable of driving the vh...just a matter of remapping pins to make it work.as far as converting to batch fire goes, why would you when the stock ecu is already full sequential...batch fire = uber crappy gas mileage and poor tuneability.

as far as jumperharnesses go you can make one with minimal fuss for a fraction of the cost of a premade one...might take an hr or 2 but then you could customize it to what you want.

as far as that mines ecu tune goes its proly nothing more than a smoothed ignition map and slightly reduced fuel...nissan targets silly rich afrs for all their engines; na engines target high 11's at BEST and mid 10's on their turbo cars.pulling fuel out of a stock map to around 12.3-12.5: on a na car will see good gains while staying safe where on a turbo car pulling fuel out to around 11.5-11.8:1 keeps it safe while yeilding STUPID gains.

[anyotherone]

For me, the answer to that question is that I'm a factory trained and certified AEM tuner. I know the system backwards and forwards and have run it in many different combinations. I daresay it has much more flexibility than the stock ECU in combination with any rom editing software that I have been exposed to.

I plan on one of two routes, ITB high revving n/a or turbo, both will require something other than the stock MAF, and I prefer MAP anyways.

For someone that is not building the motor one way or another, I agree that the stock ECU is more than capable.

[Carl H]

i hear ya man, go with what you're familar with...for people that need possibly the expanded resolution for maps that the aem offers then yeah its a good deal...but i'll still be plodding along with the stock ecu even if i go turbo or build a 9k vh.its all what you're comfortable with, the aem software doesnt really appeal to me.

[doctorchee]

did u consider the AEM universal ecu?

i actually thinking of use that but budget constrant.

did the aem 300zx ecu have all the functions like traction control etc like the aem universal ?

i using DTA P8 and re wire every actually. new wire. becuase the old harness feels crispy already.

[XJared]

the z32 aem has all the features of the universal box. using the z32 box since it plugs in would be advantageous.

[SSDwellah]

I would like to eliminate the MAF sensor and switch to MAP because

- MAFs are more expensive to replace with a new unit than a MAP sensor ($125 vs. $350+), and lets face it most of our VH45s are 18-13 years old now so things need replacing.- They have a higher range of typically 3.0 bar or 3.5 bar (GM style which is ~29psi or ~36psi respectively) versus the MAF which usually rails at 5v a much lower boost level.- They are less fragile, since they do not contain an exposed element that can get dirty, oily, or corroded. They work with a strain gauge to measure pressure, similar to the produce scale at your local grocer.

One downside is that you will have to use an additional air temp sensor (IAT).

[phantomX35]

can someone email me the pinouts or how-to to covert to 300zx aem ems.