Dissolve

This question isnt in regards to my 1LE, but in regards to my 350z. Since this is the best place for technical info I thought I'd ask.

I want to add a procharger on my 350z, get bigger injectors, and get the ECU flashed to adjust injector pulse width.( I really dont want to use an FMU) I was told by a fellow owner that the 350z's ECU has no boost sensing capability. Does that make any sense? It doesnt to me. The air either gets there or it doesnt right?

trans slam

Boost sensing ecu's are found mostly in cars that are already boosted from the factory. Like a turbo Sunbird, typhoon, cyclone or GN. The computer is set up to read pressure in a map sensor (or similar) rather than vacuum to regulate the amount of fuel in boost.

Dissolve

so tuning either type of ECU is essentially the same right? Same principle? Please elaborate

trans slam

No, it would be very difficult in your situation to make your comp from the 350z boost ready. I would advise a stand alone system. less headache and discretely tunable from a laptop.

Dissolve

Heres what I did on my firebird. (305 TPI).

Motor was all stock. Just had bolt ons. I installed a Paxton SN92 supercharger (8lbs), Ford SVO 24# injectors, and set fuel pressure to 45@ WOT.

A friend of mine on here re-did my PROM and trimmed the injector pulse width for me. (adjusted it per RPM) The car ran great.

NOW.....

What I was planning to do on my 350z was almost the same. Swap out to bigger injectors, keep fuel pressure around the same and have the ECU flashed to alter the injector pulse width blah blah. Wouldnt this work?

Most guys with 350zs and prochargers are using FMUs. I have NEVER liked using them and never will. I don't see how they can really be "fine tuned." In my honest opinion, really tuning is done by altering ECU parameters directly.

trans slam

yes you could do that.... or buy a SAFC and change pulse width when ever you want after installation of injectors..

Dissolve

PLEASE ELABORATE ON THIS^

I have asked several people over the past few days to no avail (on other sites that is). So flashing the ECU isnt even necessary with an SAFC?? I can directly alter inj. pulse width with the SAFC? I was under the assumption it only changed parameters of MAF and MAP

Thanks man

trans slam

Apexi make some good products.... we use them alot.... The SAFC can allow you to tune your fuel curve accuratley and effectively in 200rpm increments. Benifical adjustments can be made on injectors to curve their output from -40% up to +35% effectively up to 9000 rpm. this allows for larger injector use w/o fuel consumption at low rpm or idle. and if you are on the dyno or are running an accurate EGT guage it will help you dial in for an accurate AF ratio. I wouldn't suggest it or the Vtec controller to overcome map sensor codes. For that I would suggest (if the z uses a map) a Split second box. it will regulate the maximum voltage to the computer under boost conditions. Hence you won't throw a map code. So with those two items, and some big cc injectors you can tune quite a bit for amounts of boost up to 25 psi. Now mind you we haven't discussed timing yet....

trans slam

Actually widen that fuel adjustment %.... more like closer to 50%

Willie

iTrader: (1)

One thing you don't mention is whether you're currently running the MAF (1985 - 89) or SD (1990 - 92) system. You might want to edit your profile and add in your car's information. This information shows up on the left column, under your name and location.


The Problem
Neither the MAF nor SD factory systems sense "boost". Therefore, it cannot compensate for it.

The MAF system meters air. The ECM is commonly referred to as the "165" (last three digits of the P/N). Unfortunately, it is very easy to max it out when in boost. Once this occurs, the ECM cannot compensate for any additional air past the MAF's limit. This is when the A/F ratio leans out -- one thing you don't want in a supercharged/turbocharged engine!

A factory SD system uses a 1-bar MAP (Manifold Absolute Pressure). The ECM is commonly referred to as the "730". This system senses vacuum from 30 to 0 inches, or one atmosphere. Again, this MAP cannot "see" positive pressure.


The Solutions
With a MAF system, there are a couple of solutions. One is to add stand-alone components that work when in boost. For example, I've used Carroll Supercharging's Superfueler. In a nutshell, it adds fuel via three additional injectors when boost is sensed. You can also use MSD's timing retard to retard timing under boost.

The other somewhat simple solution is to convert to GM's Syclone/Typhoon, i.e. SyTy, system. This system uses GM's "749" ECM. This ECM uses a 2-bar MAP sensor, unlike the "730" system. A 2-bar MAP sensor's range is 30-inches of vacuum to 14.7-psig boost, or two atmospheres. There is a tech article within this site that outlines the conversion process to a 730 system and a second article that explains the conversion from a 730 to a 749.

With a SD system, you're more than half way home! You already have a 1-bar setup. Converting to a 749 is as simple as re-pinning some wires at the ECM and adding a 2-bar MAP.

The most difficult part in all this would be to burn an EPROM. I won't elaborate on this now as it's a highly detailed and lengthy topic.

Dissolve

Willie, hey man this is Ryan. We used to speak all the time about my supercharged 1LE. How ya been!?

Actually, my question is in regards to my new 350z. It is running a MAF....

So the major difference in boost sensing ECUs and non boost sensing ECUs....is that boost sensing ECUs can "see" air past the MAF's capabilities? Is that correct? Or is it the MAFs that can see more air???

With my 350z, can't I just install bigger injectors and get the injector pulse width adjusted accordingly? I dont want to use an FMU or anything like that.
Thanks man

Guido

My advice is to check out one of the 350z boards. You likely arent going to find what you want to know on this board.

Ed Maher

I'd just buy some DFI and jack it up like a mother and go roast some rustnags!!!!!

Dissolve

I did check the 350z boards. They dont know ANYTHING. I mean, even the sponsors on that site can't give me an answer.

askulte

Feel free to explain how the SAFC works. I'm not so much in the import "loop", so that would be all new to me Let me know if I've got it right - Is it a box that splices in between the ECM and the injectors, intercepts the signal, and modifies the pulsewidth up or down, based on MAP or MAF readings? What's the street price for one of these gizmo's? I've been toying with the idea of putting a turbo in the Durango for the heck of it, but there is only one outfit that reprograms the ECM, and no way for me to do it myself, in person. This box along with a BTM would make it possible

A.

Dissolve

Yea i think thats how it works. I'm still trying to learn myself..
The Apexi safc2 is around $350.

Here's what I want to know Guido or SlamsAm....can the SAFC directly effect injector pulse width? Or is it more indirect???

anesthes

iTrader: (12)

There is two problems with this type of setup.

1) He'll need much larger injectors, prolly twice as large as stock
on a fully bosted setup. _OR_ run an insanely high rail pressure all the time, and completly revamp the pw's.

On a FMU setup it raises the fuel pressure (from like 45-65psi) under WOT. On my car with 24lbs sv0's my injectors are at 90% DC <B>WITH</B> the FMU. Now imagine what size injector i'd need with a normal rail pressure.

2) The 2-baro map is a poorly designed setup. GM should have designed a 2-MAP setup. The resolution on a 2-baro sensor is soo spotted, your part throttle operation is going to be much worse than a regular '730 setup.

FMU's work good. Willie's superfueler is the nuts. Maybe one day I'll go as fast as him.

-- Joe

Dissolve

What I dont understand, is that I've run 8psi of non-intercooled boost on my 91 firebird 5.0 TPI. All I did was swap out to bigger injectors and get the PROM reprogrammed. Runs great. No FMUS nothing.

I imagine it wouldnt be too much different for an '89 305 TPI firebird either.

The FMU is a cheap way so you DONT have to swap out injectors. I know that.

anesthes

iTrader: (12)

Yeah, PE % vs rpm. They maxed out the injector. What was your rail pressure?

Without a wideband o2 noone (including you, sorry) really knows what your AFR was under boost.. I know vortech recommends like 11.5:1 . Others say 12:1, others say 11:1.

well if $32B version of PE is the same as $8D than it should be the same deal - max out your injector PW under PE, hope for the best.


The FMU is the way to deal with a car designed to NOT work with boost.. Even your PE stuff should be really set for NA WOT.. Then you add your extra fuel with the FMU.. If you have an adjustable FMU you can dial it in on the dyno to a wideband o2.. Your ECM will still make pw changes -/+ based on a million different calculations so you'll be pretty much where you want..

Like I said before, otherwise you'd need huge injectors and lots of experimenting time. For a while I was working on modifying $8D to read a second MAP sensor for >100kpa situations. But after lots of research and math, I realized that the only usefull thing would be timing retard. As far as adding fuel goes, i'd have to find the exact right injector and FP setting so that my smallest pw's don't run too rich, and my largest dont run too lean or max my dc.


-- Joe

Dissolve

Your right, no one really knows what my AFR was. However, I used the old fashioned way and tuned it. Was running around 48psi@WOT on the firebird. Spark plugs looked good too. The mixture had to have been right. The car was very fast, I got no knock, and my knock counts werent that bad. The car still runs like that to this day (2+ years).

With bigger injectors, an apexi SAFC and a wideband....I *could* theoretically tune my Z if I added a twin turbo kit? I know a stand alone would be ideal, but no one makes one yet for my new car.
Thanks for all the help

CrazyHawaiian

Didnt Greddy make a turbo kit for the 350Z? Write them and find out how they did it.

Lee7

you COULD take the time to calculate how much air the engine will be using at a certain RPM under boost, and then adjust your ECU to fire the right amount of fuel for the calculated amount of air.

Alot of people do it this way AND run an SAFC for fine tuning, but you would still need bigger injectors if you go this route.

The Greddy EManage is a good SAFC with alot of capabilities, it can do ignition timing too, and you can also buy an optional boost sensor. It also allows you to hook the unit up to a laptop and fine tune everything in real time while you are driving your car.

If you got the EManage with the Timing Harness, Injector harness and Boost Sensor, you would basically have a full blown boost capable ECU, and your stock ECU would basically only be used for controlling silly things like Radiator fan settings, etc.

ATOMonkey

For WOT you have several things that can happen when boosting a NA engine. First is that timing and fuel are only functions of RPM and MAF. If that's the case you can extend the upper limit of the MAF and adjust injector pulses. The timing will be very aggressive, but depending on how the knock sensor works you might not have to change timing. For part throttle driving the ECU is open loop, so the fuel should take care of itself, and the knock sensor will handle the timing again. If the OBD says to go to limp home mode in the case of too much knock or positive manifold pressure, you might be screwed. Also remember that the 3.5L Nissan V6 has variable valve timing, which is calibrated for NA, not boosted operating, so that may also be something to address.

Try emailing the people at AEM in LA, they're really good with late model electronics and can help you out. Their one size fits all ECU that they debuted at the SEMA show last year won all kinds of prizes.

Dissolve

Last question guys. Can SAFCs adjust injector pulse width? Or do they simply increase fuel pressure by tricking your MAF or MAP into thinking more air is entering engine????

If SAFCs only increase FP and NOT alter injector pulse width, wouldnt I be better off with an AFPR?

Thanks so much for the help

trans slam

no, it does actually let in more fuel....it doesn't increase FP.

anesthes

iTrader: (12)

No, as long as its warmed up all driving will be in CLOSED loop with the exception of PE. If part driving was in open loop, these cars would only pass emissions on 1 day out of the year.. heh

-- Joe

ATOMonkey

Yeah, I meant to say closed loop. Stupid electronics are backwards from everything else in the world. Even when the vehicle is warming up it should still be in closed loop on new vehicles. Cold startup is one of the hardest things to meet anymore. The only place it goes open loop is WOT, and that may not be accurate for all vehicles.

Grumpy

I'll beg to differ with you.
Premium fuel select logic, wastegate feedback from the knock sensor. Programable boost, vs TPS, and RPM.
What more would you want?.

Finer graduation for the VE table, is rather moot in my book. At least for the application it was meant to work in, ie a truck. And it runs perfectly in my car.

The 2 bar sensor has been the work horse of the boost community for years, both in oem and aftermarket form.

The way they used the boost multiplier table is a stroke of genius in my book. Seems to work just fine in alot of 11 and 12 sec Syclones. About the time they get to 10s they go to odd fire cranks so, the barrier is more the parts then the software.

anesthes

iTrader: (12)

Thats perfectly fine, Bruce, but I think using 2 map sensors would provide better part throttle/non boost driving..

-- Joe