Excellent video Shane! I had this happen on a 1,500hp drag race S10 I tune when we bumped pressure up at the race track, in my mind I figured it had to be harder for the injector to open but just didn't make the connection why it was slightly leaner at idle. I changed the fuel map of course, being much less experienced than yourself. Now I understand what to do next time, thank you for putting this content out!
I was just learning about differential fuel pressure and after reviewing my notes this exact dilemma popped into my head. Since deadtime increases with dpsi, I was wondering if that would affect the rate at which flow is achieved with the injectors, particularly when they havent opened for much time at all. since the valve might be opening at a much slower rate than usual, I figured the flow might be less initially. This was an incredibly informative video, Thank you so much for sharing this information!!!
Shane thank you so much for this information it is very helpful I was actually having the same problem on a car that I recently started tuning and change fuel pumps and I noticed this behavior but I really did not understandThe behavior of it .thank you so much for sharing
You can get close by using the old fashioned way. Nearly all injectors have become linear by 4mS unless we are talking really low voltage (less than maybe 10v) So you can run the engine at the right load and rpm to attain 4mS and keep it there. Observe the mixture, rpm and load. Change the battery voltage (disconnect charger or take alternator connector off) Go back to the same rpm and load points, adjust pulsewidth to attain the same mixture. Observe the PW. Subtract the PW from the first test. The difference is roughly the voltage offset.
Thanks Shane, it would be cool if you could make a video of your test equipment. Like what you use for the engine simulator, I don’t know the correct term for that device but you used it when testing coils. Show your scope etc. I would be very interested in that testing equipment and a run down. Thanks. Have a glorious fing day. Lol
The short story is, it took so long (and is still ongoing) and so much $ and effort to get it to the level it is today, I’m not willing to share that with anyone.
Shane T, are there any engine management systems that can account for fuel pressure changes or should the fuel pressure remain the same to eliminate that variable?
Great illustration Shane, presuming the engine in this case example runs an M1 ecu, fuel only needed to be added because the injector wasnt characterised at that higher pressure initially?
Correct me if I'm wrong but that reduced flow at lower pulse is due to the coil windings ? Your trying to open injector lower pulse with higher pressure so it will struggle more that's how I think of it is that right ?
I think you have it backward or at least the terms are backward. The opening time is the part we adjust when tuning in the engine management system. The fuel pressure is adjusted to a specific pressure and maintained. The opening time is dictated by the pressure.
Depending on the system layout, strategy and more specifically if it is Sequential (Fires one injector per cylinder in firing order) and synchronous (has a unique trigger event referenced to a specific point in the cycle) then the timing relative to the reference point can be adjusted anywhere in the cycle. Which is a long way of saying yes.
Thanks for another great video. Your ability to explain complex things in a simple way is amazing. 👍
Awesome to hear thanks for watching
Awesome info , thanks for sharing, I would’ve never guessed the idle needing more fuel at higher pressure but now know why, cheers
Excellent video Shane! I had this happen on a 1,500hp drag race S10 I tune when we bumped pressure up at the race track, in my mind I figured it had to be harder for the injector to open but just didn't make the connection why it was slightly leaner at idle. I changed the fuel map of course, being much less experienced than yourself. Now I understand what to do next time, thank you for putting this content out!
Yep happens often. Becomes clear when you see the data.
Thanks Shane for posting another excellent video.
Glad you enjoyed it
Great Stuff. Super helpful for a visual learner like me. 👍🏽👍🏽
Good deal thanks for checking it out
I was just learning about differential fuel pressure and after reviewing my notes this exact dilemma popped into my head. Since deadtime increases with dpsi, I was wondering if that would affect the rate at which flow is achieved with the injectors, particularly when they havent opened for much time at all. since the valve might be opening at a much slower rate than usual, I figured the flow might be less initially. This was an incredibly informative video, Thank you so much for sharing this information!!!
Shane thank you so much for this information it is very helpful I was actually having the same problem on a car that I recently started tuning and change fuel pumps and I noticed this behavior but I really did not understandThe behavior of it .thank you so much for sharing
Awesome, always easier to recognize when you have had real world experience with the symptom to draw from.
@@TunedbyShaneT is there a way to calculate injector dead times when you don’t have any info on the injector it self?
You can get close by using the old fashioned way. Nearly all injectors have become linear by 4mS unless we are talking really low voltage (less than maybe 10v)
So you can run the engine at the right load and rpm to attain 4mS and keep it there. Observe the mixture, rpm and load.
Change the battery voltage (disconnect charger or take alternator connector off)
Go back to the same rpm and load points, adjust pulsewidth to attain the same mixture. Observe the PW. Subtract the PW from the first test. The difference is roughly the voltage offset.
@@TunedbyShaneT thank you so much for the input I will look into that method to calculate the offset times thank you so much for the advice
Thanks Shane, it would be cool if you could make a video of your test equipment. Like what you use for the engine simulator, I don’t know the correct term for that device but you used it when testing coils. Show your scope etc. I would be very interested in that testing equipment and a run down. Thanks. Have a glorious fing day. Lol
The short story is, it took so long (and is still ongoing) and so much $ and effort to get it to the level it is today, I’m not willing to share that with anyone.
Shane T, are there any engine management systems that can account for fuel pressure changes or should the fuel pressure remain the same to eliminate that variable?
Thank you Shane didn’t know it was the square root that’s quite useful math
Yes that is EFI 101 stuff.
Great illustration Shane, presuming the engine in this case example runs an M1 ecu, fuel only needed to be added because the injector wasnt characterised at that higher pressure initially?
They were M800
@@TunedbyShaneT amazing what you can do with an m800 some 20 years after first release.
Thanks shane
Correct me if I'm wrong but that reduced flow at lower pulse is due to the coil windings ? Your trying to open injector lower pulse with higher pressure so it will struggle more that's how I think of it is that right ?
Yeah when the pulse is very short, there is not time enough to build the power you need in the winding to get the injector to open all the way.
Great video!
🙏
Hey Shane do you remember how much these 850's flowed at static at 90 PSI?
Thanks dude.
So kind of like dwell ? Edit - with higher pressure needed due to shorter opening time ?
I think you have it backward or at least the terms are backward.
The opening time is the part we adjust when tuning in the engine management system. The fuel pressure is adjusted to a specific pressure and maintained. The opening time is dictated by the pressure.
Does it ever get to where you are opening the injector ahead of the intake valve ?
Depending on the system layout, strategy and more specifically if it is Sequential (Fires one injector per cylinder in firing order) and synchronous (has a unique trigger event referenced to a specific point in the cycle) then the timing relative to the reference point can be adjusted anywhere in the cycle.
Which is a long way of saying yes.
Thanks for helping me understand !
Good info shane! Hearing u out of breath i think u should exercise a bit
No doubt that it true.
It's called passion man. Even so called, fit people can run short of breath from time to time.