The ECU is "requesting" an IPW that is longer than the available time.

It is nice Jack of Trades that you put on a duty cycle meter, what would be very interesting was the IDC on the meter when Evoscan is showing 95% though as the 104% would really give a 100% IDC which your meter showed as 99%... does fit with other observations. Trouble is most meters have a slow update rate and would need the IDC to be held constant which is difficult! 0.256x to give IPW in ms is what we've used before and I suspect this has been calculated from factory tools at some point. The ECU clock speed is 40MHz then the timer unit controlling the pulse widths will have a prescaler that chops up this clock, in this case it might well be 1024x10 which rounds neatly to clock speeds... although 10 is a slightly odd divider in microcontroller terms and the ATU section of the hardware manual for the SH705x is a nightmare to follow it looks like it can do it.

 

FWIW my car made 340whp on the same dynomite as the other car you are speaking of. 11.5 AFR to redline. Don't know if that helps any or not?

 

The scaling only relates to the AFR maps IMO. If you compensate the AFR map to have the same WBO2 curve with a different injector scaling, the IPW and IDC will be the exact same. It would obviously have an effect on the closed loop parameters too but I can't test that right now because I rewired my FP trying to track down an old issue and it obviously bypassed the low voltage/low load feature in the factory fuel pump wiring. All of my fuel trims are pegged at -25% in Evoscan since my idle FP is roughly 45psi as well as my static FP since the walbro is outflowing the stock FPR. I will be returning the wiring back to factory soon so I can better see how the closed loop trims are effected. As long as you can get the scaling to within +/-25%, the ECU should be able to achieve the stoich target values.

 

I may de-tune my setup for 19psi and then retest the IDC at the injectors. It seemed to start staying pegged at 99% in the same rpm range that I would exceed 100% in evoscan (around 6000rpm) so its possible that evoscan is very close.

 

I am curious what your IDC's were Nuked, cause Charlies were peaking at 95-96% when he made those pulls. He has since gone back and on racegas (obviously leaner) and made 396whp/418 on the same dyno on stock injectors with no meth and a 255.

The other car was running out of injector and later went on meth to compensate and that was on a dynojet. I am just wondering at the inconistency in the IDC's for a given power level. I would normally suspect that a dyno that reads high would also have lower IDC's compared to a car that is on a low reading dyno making the same amount of horsepower.

 

Bump for good reading since it has been brought up recently.

 

..

 

The one piece of evidence that needs to be considered for the IDC being based off scaling rather than injector size is the fact that fuel adjustment past 100% is possible (nearly 120 in some cases) which is impossible if it were correct.

I would like to put out there then, this:

If the IPW numbers we are seeing arent based off scaling rather than actual size as well. Has anyone observed this independent of EvoScan?

 

I am trying to borrow my friends handheld oscilloscope which can read rms and peak-to-peak PWM. I can tap directly onto an injector wire and see whats going on. I tried my meter but it was rms. I personally think its evoscan and the IPW output via the OBDII port is from the actual PWM output circuit.

 

Jamie, then you could watch the PWM and compare it to EvoScan at an idle or whatever RPM you wanted to see if the msec matches or not...awesome.

 

Indeed Well, I gotta go drop an ALT MAP switching harness in the mailbox