Fast Freddie, I'm only using a single pump so I have no need for anything like that and have no means to currently test it anyway. I have no intention of writing a patch at this point.

That said, everything you would realistically need is there currently to use the secondary pump output as a control for the second pump with a simple rewire to get rid of the resistor. Triggering off load alone is about the same as MAP and then having TPS and RPM settings is just an additional benefit over a simple MAP trigger.

 

ok, acamus is talking about Pin 21, but Pin 39 is the controlling pin for the hi/lo voltage switch-over on a USDM Evo 8. Am I missing something here?

 

His pin number isn't right, but logging that bit it seems correct.

Toss a multi-meter on the high/low relay and watch it switch. Simple revving will change the state of the output.

 

I finished up my rewire that utilizes the relay #3 controller. I did a bit of observation on my test drive, and relay #3 control switches consistently at 0 psi (crossover from vacuum to boost) no matter what RPM or anything else. The code acamus shows has nothing that would indicate a switch point at 0 psi (typically about 90 load). I suspect that the code he pointed out could be for relay #2 which is pin 21 Evo 9s.

 

I'm about 99% sure I've got this figured out. Fuel pump relay #3 is controlled by FFFF6A0C bit.6 in the 88590015 USDM Evo 9 ROM. The subroutines where the bit is set are at sub_232B4 in the 88590015 ROM. Basically, it keys off load only. Here is the table (for the 88590015 ROM):

I'll have time on Friday to test it out thoroughly and see if it can fix my slight fuel pressure overrun issue during off-boost driving with my custom rewire.

It seems that it would make much more sense to have the relay trigger off something proportional to fuel flow rather than load. I could easily rewrite the code to have it trigger off MAF Hz.

On a slightly related topic, if anyone is interested, it looks like fuel pump relay #2 is triggered by FFFF6A0C bit.7.

 

Mrfred, for those running SD, will the code still trigger off MAF Hz?

 

odd as it may sound, maf hz used in all the code in the rom is calculated from master load (which does not go away with the sd conversion), so a maf hz trigger would work with an sd rom.

 

Thanks! I thought so just wanted to verify... I know when you change MAF scaling it will mess with the SD tune...

 

mrfred, with this discovery, do you think there is any possibility to write code to enable an unused pin as a programmable output? The purpose would be to control a fourth fuel pump relay for a second fuel pump, like an electronically controllable hobb's switch.

-Acree

 

Not mrfred but yeah it is possible. Just had play with these during last weekend. Setted unsused egr and purge outputs from my own program. Even these are duty outputs, those can be used as switch output by setting duty to 100% (0x80). Nothing to release yet though but it worked on the table just fine

 

THAT sir, gets me excited. When you feel comfortable, please share your results. This will save me the time and trouble in making an electronic hobbs switch from a microprocessor.

-Acree

 

What would you like to use as trigger for setting output? What rom id? I have worked at the moment with 9653 as there was real need for that in my friends car.

 

Load would be the easiest trigger I'm assuming. I am on the USDM IX Rom, I believe 88590015?

-Acree

 

If you are talking about the bit Acamus pointed out and the code chunk I went over, it doesn't really make sense as the #2 relay. Could be EVAP related?

It is in the main CAS interrupt driven routine instead of the main loop, which seemed kind of odd to be there if it was the fuel pump change over. Doesn't seem like it would really need to be that real time to me.

The corresponding routine in 96530006 is at 205AC and I have it marked as an unknown solenoid. Table is located at 0x4568 and axis is 0x6576, should anybody be interested in testing.

When you say bit.7, are you talking bit.1 being the lowest? It's looking for 0x40, which isn't that bit.6 if you go by bit.0 being the lowest? Isn't that the typical method used? Or is this just matter of preference?

Anybody got any good ways to simulate the crank and cam signals with proper phasing? I have some stuff to build up a test bench and being able to run the ECU on the bench would make it pretty easy to make sense of this stuff as otherwise I have no way to test anything out. I've been thinking about using an Arduino to kick out the two signals?

 

I don't know if you have ever heard of Matlab, but it would very easy to simulate those signals with it. You could simply create a matrix with the correct sampling rate/phase/amplitude and then create a .wav file. Depending on what the required voltage range is on the ECU input pins, the "sound" signal coming from the computer could substitute for the real thing very well.

-Acree