Injector Opening times

This might be asking a bit much but does anyone have any specs on the stock toyota injector opening times for the 3sgte?

Ta! James

Reply to
Coyoteboy
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I do not recall ever seeing a specification for injector opening times, probably because injector opening times vary with coolant temp, MAF/MAP sensor output, O2 sensor output, throttle position sensor output, crankshaft position sensor output, and engine RPM. With all those possible permutations, it would be difficult to come up with a "stock" opening time.

Reply to
Ray O

Sorry i mis-represented my question - by opening time i meant "time between current applied to fuel delivery", not calculated pulsewidth. Low impedance injectors tend to take 0.7ms to 0.9ms to open and high impedence ~0.9-1.1, depending on flow rate and current/voltage control method. The 3S-GTE injectors are low impedance and have a series resistor. For normal tuning its not a problem - so long as you tune to a specific AFR you dont have to worry about the opening time as its fairly constant but as you approach idle, if the opening time you have programmed into your ECU is significantly inaccurate the adjustment of the VE table becomes a lot harder. For example if you have your injector opening time set to 1ms but your injector opens in 0.8ms, even if you drop your VE to 0 you still get some fuel delivered - this effect means that at low VEs your tunability goes out of the window.

I have tuned my car at cruise and under-hoof but at idle im at 12:1 AFRs and i cant seem to make it go lower by adjusting VE bins - hence the actual opening times are probably shorter than i have set, but id like to know for sure. I have scanned the net for hours and not found the info and even between two similar makes/models there can be large variations of opening time. Toyota look at me like im some sort of lunatic when i ask, as i suspected!

James

Reply to
Coyoteboy

I thought that was an odd question for you to ask, and I had thought to ask if you meant injector pulse duration or something else.

AFAIK, there are only 2 places where the info you seek might be published where the public has access - the factory repair manual, and the service training department's new model intro course for dealership technicians for the year that particular engine was first sold, although I doubt if that information is included in either of those sources. That info was not even widely available internally at Toyota. I've seen that stuff published for use by product engineers and field product engineers, but that stuff was supposed to be top secret, mainly to make it more difficult for competitors to "reverse engineer" something.

I'll try to remember to take a look at a factory service manual and see if the info is included in the ones I have.

Reply to
Ray O

Ya, and from reading the above, that's understandable! Now, I don't get too much into tuning. What is the purpose of getting this specific?

Reply to
Hachiroku

wouldn't that number depend on throttle opening, water temp, barometric pressure, inlet air temp and rpm? sammm

Reply to
SAMMM

I have an idle tuning problem on my megasquirt and im fairly sure its due to my specified opening time being incorrect for my injectors. Trial and error could find it approximately but id rather get it bang-on, also so i can switch between single and multiple squirts per cycle (engine runs much smoother at 4 squirts per cycle but the whole fuelling needs scaling every time due to injector times being wrong). The closer i can get to OEM setup the better i can push the upper end "safely".

Reply to
Coyoteboy

Badly worded, sorry, check my reply to Ray O.

Ta J

Reply to
Coyoteboy

Cheers for that Ray, I suspect it wont be there but it'd be handy if it was!

I suspect the only way i will be able to determine it is using a current probe on an oscilloscope to watch the current flow as it opens

- it should plateau as it hits "open" i think.

J
Reply to
Coyoteboy

I checked the factory service manual for a 1997 Avalon, and the spec you are looking for is not listed. It does show pulse duration at idle for that car, which is a hair over 2 m seconds but not the opening time. All they show is a graph with a picture of what the waveform should look like on a scope, and yes, it does plateau when open. Unfortunately, they only show the pattern for all of the injectors on a 100 m second scale and an expanded view of only 1 pulse on a 1 m second scale so there is no way to even guesstimate what the time between signal generation and injector opening is.

Sorry, it looks like it will be trial and error unless you can get a product engineer to do the research for you and part with the info.

Good luck!

Reply to
Ray O

Excellent info there thanks Ray, and I've just received an email back from an injector repairing company who were kind enough to part with some info. He suggested that the low impedance injectors around the size of mine coupled with a resistor pack, such as mine is, usually open in around 1.5 to 1.6ms. At idle that would equate to around 2ms pulse width in total which aligns with your information nicely (I currently have an idle total PW of 1.4 and little or no control over fuel).

But all of this confuses me as I'm currently running rich with a total PW of 1.4 so god only knows what its going to do when i set the opening time to more than that! Tuning an EFI system is a lot harder than it seems on the outset LOL!

Reply to
Coyoteboy

To me, tuning an EFI system is part chemistry, part electrical engineering, and part voodoo.

I don't know if you can set opening time and pulse width independently, but if that is possible and the AFR is already rich at idle, then if you increase the opening time, then I would reduce injector pulse width by a corresponding time. If you are running rich at idle, make sure that the ECU is getting a signal from the coolant temp sensor, that the system enters closed loop, and that the signal from #1 O2 sensor is in spec.

Reply to
Ray O

Amen to that :)

The end of the MS calculations, when you check through the assembly code, is basically commanded_PW = opening_time + fueling_PW so increasing the opening time will just increase the fuel - annoying!

Yup, running ~87C but ignoring feedback from the wideband 02 sensor for now, it only complicates matters while tuning im afraid- i use it to log my latest changes and adjust the fuelling accordingly- I will put it closed-loop when i have the VEs almost bang-on so i can set its correction parameters to low and slow to prevent surging. I'm not far off that for the rest of the table but idle is driving me nuts!

Ta J

Reply to
Coyoteboy

Good luck, let us know how it turns out!

Reply to
Ray O

Well I tried opening times from 0.4 (killed engine without leaning) to

1.6ms and nothing eased the rich mixture. I changed from 2 squirts of all 4 injectors simultaneously to 2 squirts in banks of 2 (so effectively from 2 squirts per cycle to 1, and lessening the pressure drop on the rail) and i get my idle adjustment back! Woo! I'm not sure why this makes such a difference - I'd have expected some difference (going 2 squirts per cycle to 1 means eliminating 1 opening time from the mis-fueling) but the difference was so great I couldnt have expected it.

Anyway, been out tuning again and getting a really nice OEM driving feel but with more oomph now so im grinning from ear to ear. Note to self - save configuration somewhere it cant get lost!

Thanks for your input! James

Reply to
Coyoteboy

I don't know that I actually provided any useful information for your project, but I'm glad to hear it's driving right!

Reply to
Ray O

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