larger injector characteristic

[renxun]

ok b4 i start, i admit that i have very low knowledge for injectors and thats why im here to ask.

ok here i have few differant sets of injectors of 800cc. I have sard-low impedence,power enterprise-high impedence, and RC- low injectors. for the low injectors i add resistor packs to bring them up to 13ohm so that it will be similar.

so here is the case... i find out that the sard i have a very hard time to start up.. it seems the injector is hard to crack open.. once it starts... it ran ok... so i set it richer to bring up the duty cycle abit for start up. it does start up but it ran dead rich. i have no other choice but to bring down the fuel pressure to a very low value in order for it to start normally, enough duty cycle signal to crack open and being not too rich after that...

power enterprise, i dont have any issue at all... it can be leaned down and it will start as normal car . no issue wid stock fuel pressure. easy to tune..

rc injector, easy to tune also ... doesnt have much trouble wid it.

so the question is why the sard (denso made) had such weird characteristic? oh ya when i tune up the fuel pressure my afr become leaner... i really couldnt understand at all.

[Kedderz]

Do the injectors have different pintle caps on the injectors thus varying degrees of fuel atomisation?

[BMWTurbo]

My SARD's (650's) seem to have fairly poor low duty ability also.

I've found that on a cold start in the morning the car will idle at AFR 10's. Warm idle is 14.7AFR and warm starts are leaner again. The SARDS just appear to have poor flow at low duty meaning I had to add fuel to get it to run okay. It starts and runs fine, no miss or spluttering etc, it's jsut VERY rich on cold starts.

[jondee86]

http://www.robietherobot.com/storm/f...ectorguide.htm

Maybe you are not matching the driver to the injector type ??

Cheers... jondee86

[Celica RA45]

bmw turbo what fuel pressure are you running
what you could do is up the pressure to 5 barwith a magna tec fuel reg and see how that goes
im using 1000cc sards on my 4 cylinder na motor but they are in the 2 stage set up so only from 3000 rpm upwards

[renxun]

wow 1000cc on 4 cylinder NA.... running on methanols?

[BMWTurbo]

Celica :- I was running a higher base pressure, the problem with this and std turbo's on a 2JZ is that you have to remove SOO much MAPO signal with a signal twister that the engine will ping it's head off. I'm currently only getting to 62% MAX injector duty with the 650's. My 440's were previously hitting 100% on occasion, so if I was to increase the base pressure past the stock (as I'd did have previously the twister set the MAP signal that low that the timnig was extremely advanced in areas where you don't want it). Being a 'signal twister' I don;t have an overall timing figure either, so it makes it very hard to bring the timing map back in line.

When my Hi-flo's go on however this should all start to come good as the engine will breath better and require more fuel, pushing the timing curve back to somewhere near where it 'should' be...

[renxun]

hi all.. i try another set of injector. now its the MSD (rochester injector of 1000cc). again i face idle problem. i drive it via EMU and it seems unable to crack the injector open. my fuel pressure initially was 3bar static and i have to wind them down till 1.5bar static in order to get them idle nicely. its a low impedence injector and i had a 10ohm resistor pack to drive them.

so again why is this happening.? although the tune "suppose" can be corrected via the injector change corrector but it doesnt help at all in my case. the car just couldnt start untill i lower my fuel press..

[The Witzl]

What ECU are you using?
Have you adjusted the "injector opening time"? (this will make a HUGE difference at low duty cycles if you get it wrong!)

I'd say if anything, you need some more precise tuning of the injector opening time. Injectors, being a mechanical device, inherently take a length of time to open before fuel starts to flow. Each different type of injector has a different opening time.
If you set that time in the ECU too short, then the injector will flow LESS fuel than it should at a certain duty cycle. Set it too long, and you are flowing MORE fuel.
What the ECU does is apply full voltage to the injector for that pre-defined opening time before starting PWM.
Most injectors have an opening time of approx 1millisecond.

Get the part no. of the Sard injectors you have, and look up the opening time from this page (3rd last column)

http://www.sard.co.jp/after/products...or_hanyou.html

(for example, if you have the purple, side feed, 800cc/min p/n# 63517... the opening time is only 0.75ms.... and hence the typical default opening time of 1ms is TOO LONG.

I'd say what you have is a case of setting the injector opening time as TOO LONG. This means that the ECU is overcompensating for the injectors, and opening them for longer than they need to be open to properly control fuel flow at low duty cycle.

BMWturbo - I would be almost certain this is your problem.

[renxun]

im running stock ecu wid e manage ultimate. i will try and adjust the lag time and see how it goes.

[The Witzl]

i'd say this is your problem.
The standard injectors probably have an opening time of 1.0ms, and the Sards are just 0.6ms.

Can the emanage take out fuel? I thought they could only ADD pulsewidth?

[renxun]

the e manage blue cant take out fuel but e manage ultimate can... standard injector is 0.9m/s...

im now using rochester, not sard. frm the info they ran 0.7m/s at 14v and 0.96m/s at 12v.. im not sure the 0.9m/s for stock injector is refering to what voltage...

what i did is ,
1) i didnt do any correction at the injector setup as it doesnt work anyway. so wid the stock setup, i wind down my fuel press down to 15psi and they fire up. (15psi static presure without engine start up)
2) wid the wideband connected, i slowly raise the pressure and when i see 11.5afr, i lean out the whole map back to 14afr.. and then i wind up the fuel press again..i repeat these step untill i get to idle at 14afr at 37psi (fuel press when car is idling which appx 44psi stock static pressure)
3) everything runs fine, i can drive around. but when i off the engine and restart it, it will not crack open the injector untill i add more duty cycle on it. and once it open, the plug fouled due to overly rich mixture.

above is the injector details. very appreciate your feedback

[wilbo666]

the e manage blue cant take out fuel but e manage ultimate can... standard injector is 0.9m/s...

I don't think that is correct. Both the emanage blue and ultimate can take out fuel...!

There is even an injector correction bit...



Cheers
Wilbo

[RiceburnaGTV]

Sorry to go slightly off topic guys, but I just wanted to see if adding an extra injector in the intake is old school tech?

A friend of mine has gottn all excited because the intercooler he has bought has 2 extra injectors in the intake pipe,I had no idea why and thought it may have been a water spray kit but they are fuel I was under the impression that it is rare to need to ad extra injectors these days as we have such bigger capacity ones available?

I assume this would make it somewhat harder to tune also?


cheers
Nath

[The Witzl]

Nath - adding extra injectors is a low-tech solution to the need for more fuel. Leave that sort of caper to the yanks.

Renxun - i've looked at using those rochester injectors, and they are garbage at anything below 30% duty cycle... they have no flow control down that low, hence not firing up for you. I would definitely stick with the Sards, and do some work with the injector open time and re-tune your idle.

Failing that, buy yourself some dyno tuner time