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  • #31
    GotFast? wrote:
    I would not want all the current 'returning' through that thin wire WHEN THERE ALREADY EXISTS OTHER WIRES!
    All that current? Your Mr. Electronics... Post Recall Nissan Injectors in an 88 Turbo are 13-14 Ohms. (Ill take pictures of all 6 if you want me to.
    Supplied battery voltage. Alternator charging so we'll say 13.5 volts. Injector resistance 13.5 ohms....How much currents in that wire?


    Its a moot point. Thats an injector scope pattern take on the ground side of the injector. Notice when the injector is firing there is 0volts on the ground side. How much current is there then?

    Flyback voltage spike is not of a concern. ECU is disconnected from the injector circuit and the excess voltage generated just goes back to the battery.
    Low impedance injectors are 2.4 ohms? So its almost 17 amps (instantaneous). Thats also 17 amps hitting the pin connections and solder/crimp point. It ain't moot.

    Not sure why you think that there is 0 volts on the 'ground' side. There is a voltage drop across the transistor. Thats why it is not ground. Again, its not ground. Why are you asking about current from a point voltage measurement anyway? Thats not even moot. Its just wrong.

    I again re-iterate "Show me where NISSAN is telling the customer that they are changing the injector firing pattern". They do not. They are doing something un-sound electrically in my opinion. In my opinion, NISSAN is telling the customer they are getting free injectors but changing the design (if it suits them) at the same time.

    I would strongly suggest that 300zx owners change back to stock. Go to the junkyard and try to find a 200sxse if you can for some good parts.
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    • #32
      I have an injector scope pattern that shows that there is 0 volts at the ECU with the injector driver on.

      This is taken with a Modis lab scope installed between the ECU connector and the ECU pins.

      Explain to me why you are recommending that we return the wiring to pre-recall specs. I'd like to hear your reasoning behind this one.
      ""You gota watch out in this weather. Its when them white boys with their turbos come out to play" Mr. Rimpson - UTI Instructor, refering to a slightly damp 50 degree day.

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      • #33
        My main concern would be the injector pattern changing from 123 and 456 to 135 and 246. It is splaying out the injection.
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        • #34
          and you should be concerned, the ecu can't change the mixture in response to quick airflow changes with batch firing when it's firing 6 cylinders away

          it may "work fine" stock, but at elevated hp the last thing you want is that much afr variation, you'll burn up the last two cylinders

          so does that mean nissan chose to do it for performance? no, like bum said it was just easier and even nissan decided later that it was unnecessary

          and >3000rpm all-six firing you're so proud of suffers from the same problem of fueling lag... luckily the tuning sets it up to be overly rich so as to mostly negate that problem

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          • #35
            I heart sequential fuel injection!!
            ""You gota watch out in this weather. Its when them white boys with their turbos come out to play" Mr. Rimpson - UTI Instructor, refering to a slightly damp 50 degree day.

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            • #36
              Not sure about all that you are going on about G-E but let me at least make my point clear.

              When the batch fire (group mode) is injecting banks that have 1-2-3 or 4-5-6, the cylinders are just 60 degrees apart. When the groups are 1-3-5 and 2-4-6, the cylinders are 120 degrees apart. 1 and 5 are 240 degrees apart!

              My concern is that some cylinders have intake valves that are in varying states. Since the cams are rather short duration, this may be a significant problem. The injection must take place either before the valve opens or when it is open.

              Over 3000 rpm, there is simultaneous injection. Both banks fire. But also a two-shot per injection. Meaning that the ecu fires the injector twice per intake cycle. This needs to be understood as 'splitting' the gas injected NOT doubling it.

              To be perfectly clear, let me demonstrate with an example. At the crossover point of 2999 rpm, the group mode is firing the injector once per intake cycle(lets say 5 milliseconds duration), after 3000 rpm, it is firing that injector twice per intake cycle but each injection is 2.5 milliseconds. It is also firing those two injections seperated by a time duration within that intake cycle. This distributed injection insures that the cylinders have some amount of parity in pre-opened valve and open valve injection.
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              • #37
                GotFast? wrote: I heart sequential fuel injection!!
                Heart it? OK.

                But I think that a gasoline engine would still want to to do a split pattern injection (more than one injection per intake) EVEN if there was true sequential injection.

                I say that because a shot of gas on the hot intake valve allows a true gas state to some of the gasoline. Fuel injected onto a hot surface would not 'puddle' like some think. It would flash into a true vaperous gas state. that is, not a liquid but a gas.

                So a good scheme would be to have the ecu inject once before the valve opens, and then again as the valve is just opening. This would insure a balance to all the cylinders (the real goal of fuel intake) and also have gasoline injected where it has already reached an evaporated state that will easily ignite in the first wave of combustion.
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                • #38
                  you should ignore the valves and ignition when thinking about the fuel injection, for all intents they fire at the back of closed valves

                  the issue is that if it is squirting a fixed/metered amount for 3 cylinders, the first in the firing order might be accurate but the third could be off quite a bit.... the farther away from the first the more likely and extremely the third will be off

                  the all-six mode doesn't solve that problem by splitting it, you get half the fixed/metered fueling and 3 cylinders later it adds another shot adjusted for the new metering values, but therefore is only adjusting half the fueling in response to the air, again this could be worse but it is tuned way rich

                  I'm positive the ecu doesn't "remember" the last metering values, all the injection is done according to current readings....

                  - adjusting mixture for 3 cylinders at the beginning of those cylinder's cycle in 2-bank mode

                  - in six shooter mode it is fueling all 6 cylinders half their determined fuel at #1 and based on any metering updates it adds half of the new fuel value starting at #4

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                  • #39
                    You seem to contradict yourself.

                    If the ecu is splitting its total pulse, it is doubling its uprate! thats according to your logic.

                    You are confusing the resolution of the MAF sub-system with the resolution of the injectors. The MAF is the primary control signal in the 'power' region. That is, the O2 sensor (most) have fallen out.

                    At 6000 rpm, you have the injectors firing at 100 Hz. Thats because they fire twice an intake cyle of course.

                    Your argument seems to focus on the dynamic changes in air flow at 3/100th of a second. Do you think that the actual flow of air changes that much during that small time period?

                    The MAF is a 'ganged' sensor. It is trying to figure out all the air for all the cylinders. your logic is supposing that its accuracy, and the actual distribution of that air, is dead nuts accurate.

                    The MAF is probably reading in the 4-5 volts range. That range is actually the least precise because it is in a part of the electrical characteristic that is rapidly changing. Its on the steep slope in other words.

                    Your argument is flawed.
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                    • #40
                      Fuel injection works the best when it is sequential and injected directly into the cylinder.

                      Is there a reason you have nothing to add to any of the other forums on this website?
                      ""You gota watch out in this weather. Its when them white boys with their turbos come out to play" Mr. Rimpson - UTI Instructor, refering to a slightly damp 50 degree day.

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                      • #41
                        GotFast? wrote: Fuel injection works the best when it is sequential and injected directly into the cylinder.

                        Is there a reason you have nothing to add to any of the other forums on this website?
                        I guess you are supposing that there is enough time to do that? At very high rpms, you only have so much time. Unless you have a very high pressure/flow fuel system, you probably have to start before the valve opens even if you have sequential injection.

                        I added something in the lounge. Looks like it got deleted. Thanks for asking.
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                        • #42
                          Direct cylinder injection - A high pressure fuel deliever system where the fuel injector is located directly in the combustion chamber, similar to a spark plug.

                          Chevy uses it on the Sky Redline and Solstice GXP. Its a 2 liter unit the creates 260 horsepower 260 foot pounds of torque and still gets over 20 miles to the gallon in the city.

                          You can run higher compression ratios with more boost due to the cooling nature of fuel vaporizing.

                          So you know everything about fuel delivery and nothing else about the rest of a car? Sounds like an awesome idea right there.
                          ""You gota watch out in this weather. Its when them white boys with their turbos come out to play" Mr. Rimpson - UTI Instructor, refering to a slightly damp 50 degree day.

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                          • #43
                            That wouldn't be an 'idea'. It would probably be described as an area of interest.

                            But I am mostly interested in the embedded control/metering/injection/electronics aspects. Turning nuts and bolts, tunes, shining the paint, etc. is old hat.

                            In any case, internal injection is not new. Its been used in diesels for quite a while.

                            With that system, you could then actually inject during the compression stroke? You are not limited to the intake valve duration event. But what effect that would have on the flow rate (similar to 'fighting' turbo boost) would be interesting.

                            Looks like something to google.
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                            • #44
                              me masta, him blasta....

                              seriously don't you think that on a LARGE turbo like a holset or gt30 that once it starts spooling you have a good second or two (or say wot on the autobahn up to top speed...) where the airflow keeps increasing rapidly?

                              so if you agree with my premise that the batch injection adjusts slowly to the airflow (lets ignore the nebulous issue of accuracy) and you accept that the cylinders might be running a tad leaner than they should....

                              then suppose you have a fully spooled turbo and bov... then you shift, you get zero airflow for a second, then the next you have airflow reading 6 cells away in the table.... but since you already allocated next to nothing for the 3 cylinder group before the sudden rush of air you potentially have 2 cylinders super-lean, and as the airflow ramps violently you can have all the cylinders super-lean for several revolutions before the ecu sorts it out....

                              now start complaining about the fluid nature of air and all that and it won't fill the plenum and other bs....

                              then I start explaining that you could read very little airflow at the afm just when you open the throttle because the remaining unvented high pressure air will try to equalize into the plenum quicker than the additional air is sucked into the turbo.... again leading to lean afr until the ecu corrects the mistake by going into the rich end of the table

                              in short there's no reason a turbo car has to run 11:1 afrs or even lower than 13:1, except that until very lately the oem hardware has been a bit too slow .... not necessarily an issue with high end sequential fire standalones

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                              • #45
                                I do not agree that batch injection can not keep up. You do know that batch injection is only used at under 3000 rpm?

                                When anyone says..."lets ignore the nebulous issue of accuracy". They are just trying to argue for the sake of argument (or trying to save face). This is all about update rate, accuracy and precision (just as most engineering arguments are).

                                You need to appreciate the dynamics and limitations of the stock system before going on about other things.

                                As an example: At 3000 rpm, the update rate could be 25 times a second. Thats 0.040 seconds. 40 milliseconds. In other words, don't say "seriously don't you think that on a LARGE turbo like a holset or gt30 that once it starts spooling you have a good second or two (or say wot on the autobahn up to top speed...) where the airflow keeps increasing rapidly?", because, seriously, this does not reflect reality.

                                The reality is that it is possible that every 40 milliseconds, each bank is being updated off the MAF. That is, the MAF signal is being read (converted to digital), crunched and a new PWM calculation delivered to the driver circuit to control the injector. If anything, the lag on the calcs would probably lean out the mixture slightly.

                                You , again, ignore the MAF and its ability to measure individual cylinder variations. In a stock 300zx intake system (which is not very good), its a big issue.

                                Try to address issues raised in someone else's post before flying off on fantasy conversations where you try to put words in someone else's mouth. It will make you appear as a rational person if nothing else.
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