It's quite possible that there is a minimum amount of time the injectors are allowed to open. There is no reason to do it, but there is also no reason not to do it.
Ira
It's quite possible that there is a minimum amount of time the injectors are allowed to open. There is no reason to do it, but there is also no reason not to do it.
Ira
Do you have access to an ocilliscope? it may help to monitor the pulses while you play with the tables to get it right.
2001 Camaro SS
EFILive Custom OS3
The real problem isn't the drivers, its the injectors, and the way we control them.Originally Posted by GMPX
Basically what is happening is that the 96 lb'ers are like a big heavy truck, and the stock ones are like a VW beetle. The engine in the ECU that drives the beetle (stock PCM) was programmed to work well with the VW's, but now that we put that engine in the truck(big injectors), we can't get going from a stop very easily...then once we get going, we are using the brakes from the beetle to try and stop again...
In essence, we lose control of the actual movement of the pintle inside the injector. Most stand alone ECU's compensate for this by regulating the current flow to the injector at opening and closing time. They do this by using a PWM strategy on the trigger side of the driver.
With the factory PCM, we have more of an analog type signal to the injector driver....on when its time to turn on, and off when its time to turn off. This can normally be compensated for well enough by simply increasing the PW demand over the theoretical amount required for the flow you want by the amount of "lag" or dead time the injector has.
Example: you need 2.5 mSec of flow out of the injector, but it has .8 mSec dead time, so the command PW equals = 3.3 mSec
The real problem though in controlling the injector is how well the oscillation of voltage (created when you open the circuit) is dealt with.
Most ECU's have a simple zener diode (typically about 5-10 watts and 35-40 V) to avalanche this "kickback" voltage to ground.
Again though because we can control the current through the circuit with the aftermarket ECU's you can custom tailor the control strategy for each individual type or part number of injector to get the control you want.
When you just take the signal from a saturated driver, and apply it to the signal side of a P&H driver, you do gain the ability to sink the current to the injector without letting all the smoke out of your PCM, but you don't necessarliy gain any more accurate control over the injector itself.
I am sure there are tables somewhere inside the PCM to deal with this, but they probably are not obvious because the PCM was designed only for one kind of injector, so there wasn't much need to make it adjustable.
Now that I think about it, we might be able to play around with tables:
B4006 and B4005 to get a useable solution????
Basically if anyone could do some testing and find out if changing these settings helps, hurts or makes no change, that would be great!
-ben
"Freewheeling diode": soaks up the injector coil's inductive back emf when the driver circuit opens to protect the driver transistor from popping.
Cheers
Joe
There is a injector current table. I am going to log this table and then lower the current and see what happens. There has to be a way to control this injector. My afr at idle is also a little erratic. When I figure out out. I will write something saying how I did it.
Geez, does'nt everyone run 96 lb injectors?? I feel like I am in completely unknown territory!
'71 chevelle
Twin turbo ls1
1000 HP 93 octane street car!
96 lb injectors
Yes you are in unkown territory without a map and blind :lol:
I have quite a few cars running the big injectors and the same box , but they are combo's that can make use of the big injectors down low , on a stock cube motor you ar always going to have problems controlling the injectors at very low flow rates.
I have got around it with tuning but I would not say its 100% to my satisfaction but thats why I get paid to spend countless hours tuning monsters.
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