chts discussion, enriching trick?

[crowbar]

Do I think its better? Yes. And so did the Nissan engineers. I do hope its obvious from looking at the link I provided that the pulse widths for the 'two-shot' is just an attempt at a distributed control of the amount of fuel.

Well I am waiting for you to provide some proof that only turbo models use both types of injection.

[OR-Zman]

GE- Thanks for the clarification. :wink:

[G-E]

crowbar wrote:

at 6000rpm you are firing injectors at 600 times per second,

At 6000 rpm, you have a rotational speed of 100 revolutions a second. You seem to imply that each injector is 'firing' each revolution? Is that correct?

sorry I should actually correct that, above 3000rpm it links both sides and fires them at the same time for half the duration, which in theory is the same total amount of fuel at the same pulse frequency relative to rpm

so at 6000rpm/60=100/sec you are firing each injector driver twice per revolution per second, so the 600 should be 200

insomnia will do that

however like everyone keeps asking.... how is this better from a power/economy/anything standpoint?

- it may be better for fueling with the post-recall wiring above 3000rpm but not below?

- slightly reducing the duty cycle of the injectors, but adding more opening/closing time?

- preventing the injectors from overheating, if they had an injector fan someone thought it possible?

[crowbar]

I have both the 86 and 88 300zx FSM and neither states anything about 'turbo only'.

In fact, the 86 states that the car goes to simultaneous if the commanded PWM time is greater than 6.5ms also.

I would expect any EE with an oscilloscope and half a brain to know why it is better!

Sequential injection has nothing to do with this discussion.

[G-E]

I'm thinking, it's possible nissan decided that the post-recall wiring shouldn't affect the fuel delivery in boost because boost comes on somewhere in the vicinity of 3000rpm

and the reason my88+ ecus which are probably smart/quick enough to run sequential injection didn't is the size of the injectors (read: small) and there would be no point converting the car over, would just create more work, that said I still don't understand the wiring change

the 1989 sequential z32 ecus are proof that jecs had already sorted out the hardware in that time, they could have left the injector wiring and made sequential fire ecus for 88, considering they gave you all upgraded design injectors as part of the campaign

[Alex86na2t]

crowbar wrote:

I would expect any EE with an oscilloscope and half a brain to know why it is better!

Do you say i have no brain? I am an EE @ michelin and guess what, you make no sense what so ever. You just want to flaunt knowledge and make yourself look good. Yea, you are just trying to stroke your ego.

2 squirts per revolution? lets say for 5ms. That is no better than once for 10ms. You are just playing with frequency and using more current one way because a fuel injector is an inducter, so you are getting more reactance out of it.

[G-E]

I'm just waiting to see how long it takes for another topic split hahah

[crowbar]

Actually, I tried to explain how it works, get jumped on for doing so, then I am berated later to explain everything!

The obvious benefit is distributing the fuel injection during the intake cycle. Again, that is what Nissan bothered to do.

I believe people here are flaunting very bad technical mistakes.

[G-E]

is it me or have I been posting way too much lately?

crowbar, bum is right all you do is blather on how terrible we are without a shred of evidence or even theory of operation that would explain how what you suggest is better is actually better

it's not so much the lack of evidence either, there's many things we don't have the budgets to test, but explain why no one can grasp/understand/imagine why you say what you do? is it because you are a super-genius and we are all stupid amoebas? or perhaps there's something fundamentally wrong with your argument?

[crowbar]

Please. Do not insult Ameobas like that.

Seriosly. Look up Ad Hominem.

[G-E]

there you go not answering the question(s) again....

put up or shut up

[crowbar]

In all seriousness, the correct question to ask is "If simultaneous is so great, why didn't the Nissan Engineers just use iit all the time?".

More than likely, Bum is correct in that it might have been percieved as a reliability issue. He is correct about the injectors doubling thier duty cycle. Its also the transistors that allow that switching (not sure what he means about a 'power supply'). The car uses the alternator/battery? It has quite a substantial power supply. Since most cars have 'recalled' injectors or replacement by aftermarket, I think this is a non-issue. I drive my car a half hour to an hour every day over 3000 RPM (when simultaneous is used 'naturally'). My concern would be the 'ecu' being the weaker link. Possibly more so for the lower resistance injector type cars. The reason being trivial. I have extra heat-sinking on my ecu as anyone should.

The main benefit IS the distributed introduction of fuel during the intake stroke. Its a poor man's sequential if you will. But it has a side benefit also. Bum is actually backwards when he is making statements about 'pooling'. The fuel, when it is dumped out in Group Injection , will pool more than Simultaneous injection. His argument is flawed. By injecting twice, one short pulse will more than likely hit the very hot closed intake valve. This will allow the liquid fuel droplets to become more of a true gaseous fuel state. When the valve actually opens, the second pulse of fuel will be directly injected into the open valve.

Gasoline actually burns in two parts. I assume everyone knows this. Since mcx is a fireman, he will actually tell you that most 'burning', like a campfire, is also like this. The second phase of burning is dependant on the by products of the first phase (as we all know). The first injection of fuel in simultaneous injection, by going into a gaseous phase, provides the first phase of combustion these byproducts.

[crowbar]

mcx wrote: i posted before about trying Crowbars CHTS mod and recommending this mod... its convienant to have two settings with the throw of a toggle switch..its not a permanent mod like crushing a FPR....my car[remote turbo 88 vg30 200sx] has the same gremlins as most vg30 Nissans.The cold start device comes off fast idle alittle to soon and the idle is a little crappy until it gets fully warmed up.This clears that up immediatey....I find with the price of gas that i'm using more of the 87crap grade than i used to purchase,with the toggle in the off setting the timing is set exactly stock and the car wont ping...but if i'm using better grade 91-93 gas,i throw the sitch on and the car feels great with the advanced[10 degrees] more timing on the better fuel..its a good mod to try for the little effort needed to install.

I suppose you could also use a full throttle switch from the TPS from an auto tranny car. So when you mash the accelerator, the car will 'switch' from normal CHTS reading to the 'cool' reading (resistor is series-in). Not sure how fast the ecu 'scans' and reacts to sensor input though.

I hope to sign out an Agilent datalogger from work. This would answer that question as it can do 60 voltage scan/samples a second. I could also sample MAF and many other voltages too.

mcx used this mod with both a 86 NA and a 86 turbo 300zx ecu in his vg30 car (9:1 turbo mod).

[Bernardd]

Do you have timing and afr datalog's? I'd like to know how much you can increase the afr's and what rpms it effects......

[G-E]

crowbar wrote: I have extra heat-sinking on my ecu as anyone should.
love it, you do realize the safe temperature for most electronic components is around 85C and for ic's and chips of various kinds is on average 65C, which probably explains why our ecus don't catch fire while driving on the highway or sustained high rpm

shall we argue how nissan engineers know what they are doing but somehow jecs engineers really don't? no, lets move on

crowbar wrote: The main benefit IS the distributed introduction of fuel during the intake stroke. Its a poor man's sequential if you will. But it has a side benefit also. Bum is actually backwards when he is making statements about 'pooling'. The fuel, when it is dumped out in Group Injection , will pool more than Simultaneous injection. His argument is flawed. By injecting twice, one short pulse will more than likely hit the very hot closed intake valve. This will allow the liquid fuel droplets to become more of a true gaseous fuel state. When the valve actually opens, the second pulse of fuel will be directly injected into the open valve.
oh did you misread the diagram you posted where it even shows how both injector pulses are the same across all injectors.... and last I counted there were 6 injectors..... so if it only fires twice.... that means only two of the six possible valve openings will coincide with fuel being squirted, except even they don't exactly

let's allow crowbar to get his calculator a t-square out and graph this, nevermind reality, let's press on

crowbar wrote: Gasoline actually burns in two parts. I assume everyone knows this.

really? is that like cooking a hamburger on one side then flipping it over? quick someone tell the oil companies you can burn fuel twice....

damn the torpedos...

crowbar wrote: Since mcx is a fireman, he will actually tell you that most 'burning', like a campfire, is also like this. The second phase of burning is dependant on the by products of the first phase (as we all know). The first injection of fuel in simultaneous injection, by going into a gaseous phase, provides the first phase of combustion these byproducts.

so let me get this straight, the puddle of fuel on the intake valve becomes "gaseous" and starts to burn like a "campfire", and turns into some three byproducts - none of which is the usual smoke and soot from burning hydrocarbons - which is then followed by more fuel that does what exactly?

......