if it is indeed a temperature issue, as in the injectors are getting heat soaked, do you think that changing the little aluminum adapter into a different material ( PVC ) or maybe even steel , could change these charateristics.. just at thought.

 

I am starting to really think it has something to do with temps and the fuel injector locking/not opening (whatever you want to call it) on the first set of cranks...especially the more I am looking at logs and such during start-up.

Here is a log I just did after my car sat for 3 hours at work today - the first set of cranks the car according to the wideband is not getting any fuel at all. After I stopped cranking I stopped and let the wideband read before I started cranking and it didn't move - then when the car finally started on the next set of cranks it started and was pretty rich (dipped into the 10's)

I attached the log....I need to get the car cranking and pull a plug after it wont fire and see if they get wet - will try and do this after work, its a nice day here finally after it rained all weekend.

 

I wonder what could be causing them to not open during warm starts but work ok during hot and cold starts.

 

if the fuel gets trapped at the tip of the injector and vaporizes?

 

Pressure needs to be supported by pressure. Any vapor at the tip cannot be at higher pressure than the fuel rail pressure unless there is some anti reverse flow check valve in the injector.

 

I'm thinking that maybe the injector coils are being cooled when fuel is moving through them. However when you stop the pump and let the car sit, the coil heats up and doesn't perform as one would expect. Couple poor coil performance with reduced battery voltage during cranking and the car ends up "sputtering" to life instead of briskly cranking to life. The question now would be, why on stock ecu EVO's and no other combination of either aftermarket ecu in and evo or other brands of cars? Perhaps the injector drivers in the stock ecu cars just isn't as good as many after market ecu's? I know Motec's have baller injector drivers.

 

Keep in mind that saturated injectors are not designed to work with a high power injector driver box, so the only job of any ECU with a saturated injector is to close the circuit.

 

here is a start-up vid of my car....this is after 1 hour of sitting.



I will try and get a video of the FP gauge during cranking as well.....

 

Has anybody tried plugging the injector resistor box back in to see how that affects warm starts? Does anybody have the part number/manufacturer for the injector driver on the evo 9 ecu. Travis has my evo 9 ecu or I'd check it myself. I have an evo 8 ecu that I can check here but would like a number off a confirmed "hard start" ecu first.

 

that's a terrible idea.

 

Very thought out and insightful. Would read again.

 

Where do I find it - I can look on my ecu, still need to swap it back in before the weekend so I can drop off your backup ecu at your place saturday.

 

Thats right, do it to your ECU, I don't want you stabbing and scratching mine. Pry the case near the plug and put spacers near the 4 locking tabs and the board slides out. Normal electronics precautions apply, do not touch the board etc without a wristband. Below is what I *think* are the drivers. I basically looked for four of the same device that looks like it would be a transistor, FET, or MOSFET and said, humph, that must be them. This is on a 2003 evo 8 ecu.




I got the number K2926, and out of context with respect to manufacturer that doesen't mean much to me right now, or maybe it does. I'll find out later.

Again don't touch the board and don't go sliding around on the carpet in your slippers and socks.

 

ZedX...I had a customer car come in with the resistor box still hooked up. While its not the best doing the opposite is worse (running a car meant for high impedance with low impedance and no box). It doesnt hurt the ECU but it makes it VERY HARD to restart hot even. Throws off idle afrs (wont stay consistent, trims or no trims), and cruise is somewhat erratic as well.

 

Would somebody (travis) please amuse me and plug the resistor pack in when the car *should* be hard to start. I want to see if we have inductive flyback on a hot injector coil that doesn't play nice with these injector drivers (or some other weird capacitance mismatch issue). The extra resistance of the injector resistors should effectively retune our RLC circuit so that you can at least get a result (or a sputter) on the first crank. Like tony said, no problems on other ecu's and/or standalones in an evo.