Author Topic: It's alive!! Power Commander III + 36 lb/hr injectors (Read 10674 times)

ClubSport · « **on:** November 14, 2006, 09:53:11 PM »

Well I can't believe it, but she fired right up and idled!

For those who haven't seen it, I followed Shawn Fogg's idea to use a Power Commander for a Suzuki GSXR 1000 to add larger injectors to go with the DASC. This gets rid of the rising rate FPR, and adds much more tunability to your AFRs. As far as I know there's one other guy who's done it on an M42. I loaded in a zero TPS map with a first guess of -53% pulse width, but the wideband showed it was a few points rich. I gradually stepped it down to -62% and got it to stoich. Now I have to button up the loose wires everywhere and find a place to stow the PCIII box itself before I can take it out and road tune it.

The interface on the laptop shows TPS%, rpm, and injector duty cycle. I can tune the injector pulse widths at 0, 2, 5, 10, 20, 40, 60, 80, and 100% TPS, and in 250 rpm increments. The PCIII basically sits inbetween the ECU and the injectors and stretches or compresses the ECU's desired injector pulse width. Obviously adaptation will undo whatever isn't stoichiometric during closed loop, but in open loop I can dump in fuel.

Let me know if anyone wants details of the hardware or the install. The wire colors were a little different than the M44 in Shawn's writeup.

I didn't make the "current fooling" array of resistors that Shawn set up, I'm going to wing it and see if OBDI does the same current checking.

Now I just need a MAF conversion! bmwman91 how's it going?

bmwman91 · « **Reply #1 on:** November 14, 2006, 11:36:43 PM »

Very cool! I looked into a PCIII at one point to tinker with, but funds were tight.

The MAF SHOULD be working soon enough. I have some electronics hardware coming tomorrow that should complete my "lab" of stuff needed to finish V3.0

ClubSport · « **Reply #2 on:** November 15, 2006, 12:52:21 AM »

Great, I'm looking forward to it.

I took it out on the street for a little test'n'tune and it seems to be running very well. I can actually see it go rich when I nail the throttle, which is something I could never get to happen with the baby injectors. I just need to make a throttle stop and hire a friend to ride shotgun and tweak while I drive. Driving at night while typing on a laptop blows.

Tonyb · « **Reply #3 on:** November 15, 2006, 02:53:55 AM »

How does the DASC compare to stock? (seat of the pants feeling?)

Gunni · « **Reply #4 on:** November 15, 2006, 07:00:54 AM »

This is a piggyback unit that gets pwm signal from the ecu and then based on inputs from the load and map in the PCIII extends or shortens the pwm signal?

If so, this is the perfect way of piggyback tuning, when you change the fuel normally on piggybacks the load signal is changed, thus messing with the ecu�s ignition maps .

ClubSport · « **Reply #5 on:** November 15, 2006, 10:47:08 AM »

Quote from: Tonyb;13805

How does the DASC compare to stock? (seat of the pants feeling?)

The difference is huge. Stock the motor had no balls below 4000 rpm, but now it can really crank down there. It never runs out of breath either. First gear is almost useless, even with the 3.23 diff.

ClubSport · « **Reply #6 on:** November 15, 2006, 10:49:00 AM »

Quote from: Gunni;13818

This is a piggyback unit that gets pwm signal from the ecu and then based on inputs from the load and map in the PCIII extends or shortens the pwm signal?

If so, this is the perfect way of piggyback tuning, when you change the fuel normally on piggybacks the load signal is changed, thus messing with the ecu�s ignition maps .

Correct, it doesn't mess with the ignition maps because it doesn't modify anything that goes into the ECU, like the AFM. Except O2, obviously.

Gunni · « **Reply #7 on:** November 15, 2006, 12:12:39 PM »

I NEED to get Perfect Power to built that kind of a piggyback unit
Alot smarter then what is normally done

Alpine003 · « **Reply #8 on:** November 15, 2006, 12:46:32 PM »

Nice alternative.

Another that I was contemplating at one point was to use the older SDS EFI additional injector controller or the HKS AIC to plumb in 1 or 2 additional injectors into the system and would only be activated by positive boost pressures.

One thing I found about using larger injectors is that depending on the size of the injector, it can be hard to achieve a very smooth, stock, steady idle.

What kind of injectors are you using and how's the idle(and low rpm characteristics) on the car?

ClubSport · « **Reply #9 on:** November 15, 2006, 10:20:04 PM »

They are Lucas injectors that I bought used off a guy on bimmerforums. The idle is great, actually. I was a little worried that I'd be getting near the minimum open/close time at idle, but it turned out just fine. And no check engine light yet from the ECU not seeing the expected current from the injectors.

The problem I can see with increasing fuel based on boost is that the supercharger can create boost even at relatively low throttle positions, i.e. closed loop. What I saw during my brief road testing is that the ECU immediately trims out excess fuel during open loop. I can't even fatten it up briefly during moderately heavy acceleration. On that note, does anyone know for sure at what throttle position the transition to open loop occurs? Isn't it around 80% or something?

Alpine003 · « **Reply #10 on:** November 16, 2006, 12:30:06 AM »

Quote from: ClubSport;13873

The problem I can see with increasing fuel based on boost is that the supercharger can create boost even at relatively low throttle positions, i.e. closed loop.

Huh?:confused: Boost is boost and as long as you're below 0 psi, the factory program should be able to compensate just fine because below 0 psi, you should techincally be in "na" mode. Maybe I'm not understanding you 100%.

ClubSport · « **Reply #11 on:** November 17, 2006, 03:00:05 AM »

What I'm saying is that at 50% throttle position I may be making 3psi boost, and want to richen it to 13:1 or something. But at that throttle position the ECU may still be in closed loop, adjusting whatever I fuel I add back to 14.7:1.

Gunni · « **Reply #12 on:** November 17, 2006, 10:38:35 AM »

Then take out the O2 and re tune the engine with the power commander, it must be able to run closed loop, if so hook up the o2 to it instead of the ecu

Alpine003 · « **Reply #13 on:** November 17, 2006, 11:34:51 AM »

Quote from: ClubSport;13934

What I'm saying is that at 50% throttle position I may be making 3psi boost, and want to richen it to 13:1 or something. But at that throttle position the ECU may still be in closed loop, adjusting whatever I fuel I add back to 14.7:1.

The question is at what point does the BMW M42 ECU switch over to the open loop maps. I know some ecu's are more sensitive in relation to throttle position/map readings than others. Some do it way before wot is achieved and some only stay in closed loop only for steady state cruising amongst other things.

One interesting aspect that I came across while my '02 sensor crapped out is that you can somewhat measure the point where it switches from open loop to closed loop by disconnecting the O2 sensor. The car should still run good(albeit a little richer). The cel won't stay on all the time but will go on at various times. I would assume this is when it is switching to closed loop and unable to find an O2 signal. This is when the light would flash on and eventually go off. This can merely be a simple correlation at best but a simple thing to try nonetheless.

ClubSport · « **Reply #14 on:** November 17, 2006, 10:26:32 PM »

Quote from: Gunni;13943

Then take out the O2 and re tune the engine with the power commander, it must be able to run closed loop, if so hook up the o2 to it instead of the ecu

I'd like to take out the factory O2 sensor, since I have a wideband, but then I'd be driving around with a check engine light on all the time, which could conceal a real problem.