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Discussion and questions related to the course Practical Standalone Tuning
Question . I have a 2.1 ecotec engine . L61 block lsj head . Lsj crank rods and pistons. On the fuel tech ft450 ECU it has a generic setting for injector phase angle off 400 degrees. How does one correctly find the right angle ? Would I look at the crank trigger and wheel Wich is a 60-2 . And the offset is 120th tooth? But I don't have a cam sensor . I'm using wasted spark. I think I'm making it harder the. What it is for my self. Could any one slap some input to me ?
The injector phase determines when in the engine cycle the injectors either start opening, or complete opening (i.e. end-of-injection). Normally it's easiest to have end-of-injection. While you may find some small gains, it not unreasonable to just use constant value of 380 - 440 degrees.
If you do want to tune this, what you do is vary the injector phase and see if the mixture goes lean (ie, more fuel is being used for combustion and not wasted) -- if so, find the phase angle for the leanest mixture, then adjust the mixture back to your target for maximum power. If the mixture get's richer as you change the phase, then you are going the wrong way, or need to go further to see if it ever starts to lean out.
Sometimes using a different phase value at starting RPM will help the engine start better.
David thanks again the great input ! You rock man!
David I have one more question I'm sorry to be a pest but just want your personal opinion on input on this. So explain the block the head in the Pistons on the first post I got aluminum fuel rail 101 reference fuel pressure regulator 10 gallon fuel cell walbro 370 lph grams 1000cc injectors. Custom manifold to mount external wastegate 38 mm and a t3 t4 6267 trim turbo do you think I'm running too much excessive fuel maybe too big of fuel injectors I'm having the issue now at idle where black smoke Puffs out every once in awhile and I notice on the wideband I'm running down to 10.9 11.2 I noticed some of my perimeters were wrong though so I have to recalculate for the computer but even if I pull fuel it's still running rich could it be because I have something entered in wrong on my fuel settings or is it because I'm throwing too much fuel at the motor. Could I load my data log or would that be too much for your input. I've been a mechanic for about 18 years but tuning has always fascinated me and I've understand the basics but I'm really trying to grasp the full fundamentals of it
Normally 1000cc injector shouldn't be an issue, unless the ECU doesn't have the resolution to control them accurately. If reducing the fuel in the fuel table does not change the mixture as expected (ie, if you have AFR 11.0 and want say 13.5 at idle), if you change the table cell in the fuel table by 0.81, and don't get 13.5 then I would suspect that your injector dead-time parameters are not correct -- Errors in injector dead-time show up more at low pulse widths (idle) than anywhere else. Some ECUs also have a minimum opening time parameter, I would just make that smaller to test if it is affecting anything.
I assume your fuel pressure regulator has a manifold pressure reference (i.e. below the throttle plate) -- if you are using boost pressure reference (above the throttle plate) then the ECU may not properly compensate for the change in differential fuel pressure at idle).
Okay you are the man bro. So I noticed after reading this over ten times and re watching efi fundamentals 4 times 😂 my numbers were way off. I correct injector dead time compensation . Fix the flow rate asks for. And had the wideband data set up wrong. The only question I have left Dave is for grams 1,000 CC injectors the data sheet it gives me is for the battery offset. Now on fuel tank in engine setup asks for a primary injector dead time . On the chart posted below is shows all the differences from 8 bolts to 16. And psi from 43. Too 100. . so now do I go off of 14 volts the car runs around 50 psi so it's going to be an injector dead time of 1.050? Is there something I'm not seeing here?
So if your ECU only has a single "injector dead time", then yes you would use the 1.05 ms (or 1050 micro-seconds).
Some more sophisticated ECUs might have a dead time compensation that allows various battery voltages (so the deadtime would increase when cranking and the voltage drops). You will just compensate by using a slightly larger injection time when cranking. Any other slight errors will just get baked into your fuel table -- don't worry as long as you can tune the fuel table to hit your target wideband reading.
Just be aware that with a single dead time offset value, if your battery voltage changes from the value set when the engine was tuned, then when your injector dead times increase without a commensurate increase in the actual delivered pulse width, the longer dead time is using up injector cycle time and reducing the time that the injector is actually open for. This will lead to the engine leaning out.
Voltage = 14V, Dead time (DT) = 1.05, Tuned PW (TPW) = 4.55, Delivered PW (TPW - DT) = 3.5ms
Voltage = 12V, DT = 1.35, TPW = 4.55, Delivered PW = 3.2ms
This change in voltage without a change in the dead time leads to an approximate reduction in injected fuel of 8.5%
Okay so I was able to input a injector offset values on the map for 11volt 12 volts 13 volts and 14 volts. On engine set up it asked for primary injector dead time . On the injector dead time sheet it lists the injector offset values. Not a single value . So I imputed the volts that the car charges on 13.7 Wich is 1.058. I'm going to run the car today to see how it goes thanks for all the help guys