INJ duty cycle 0%

[OpeLok]

So basically this is what's keeping my car from running. Using Power FC, it shows the injector duty cycle setting back to 0% 1.5 after crank period. The car will start every time, and then die. The power FC has been tested on another RB20, and works fine, and the wiring harness has been double checked and ohms tested on every pin and was built locally by someone who is considered one of the best here in PHX. CAS has been tested and while rotating by hand you can hear all injectors and coil packs firing.Things that have changed since I last drove it over a year ago (not that some of this stuff matters).

Intake ManifoldMaf is now blow through setupWiring harnessIAC and AAC eliminatedIC and IC piping Wiring harnessvarious vacum hoses

Current setup:Z32 MAFT04E turbocustom intake manifoldSARD FPRSARD 550cc injectorsfactory coil packs

the thing that gets me is that I drove this car, parked it... tore it down, and now this **** happens. I've double checked all connectors and made sure everything was tight and clicked in... I just don't get it. HELPO! p

Modified by OpeLok at 9:29 PM 4/26/2008
Modified by OpeLok at 10:45 PM 4/26/2008

[Carl H]

what other symptoms are present?perhaps damaged cas drive?

[OpeLok]

Forgot to mention that I've swapped the CAS with a known good one and same result. Doesn't matter where throttle position is... no change. Injectors just seem to power off as it's show on the PFC.

here's a shot of what I'm workin with:

[Carl H]

hrum...are the sard injectors low imp and if so do you have a resistor pack?

[BoostFab]

hrum...are the sard injectors low imp and if so do you have a resistor pack?

i was going to say the same thing with the resistance of the injectors. don't run it it if the impedance is wring, it will burn your injectors driver on the pfc, measure the imp. on the injectors, if it's 2-3ohm then you need to wire in resistors to work properly.

[OpeLok]

well I was running these injectors before with this turbo and everything. Only minimal changes were made from then till now. Injectors are direct replacement, high impedance. I paid extra for the peace of mind not having to worry about resistors, etc...

I appreciate the brainstorming that's going on

[BoostFab]

recall waht changes you did ?

[OpeLok]

Intake ManifoldMaf is now blow through setupWiring harnessIAC and AAC eliminatedIC and IC pipingWiring harnessvarious vacum hoses

[USMCgetsome]

simple check. U said wiring. So check if you made a lil mistake at the eccs relay. Such as 12vdc constant now changed to 12vdc switched. Probe it with a volt meter. also, afm. Swap em out see how that goes.

[Darius]

Since you upgraded the injectors and MAF, did you change the appropriate settings in the PFC to match?

[mello88]

Maybe not your no-start problem but it looks like you'd have a huge vac leak running your PCV like that.

[gawdzilla]

IAC and AAC eliminated seems like a pretty big deal to me. how are you controlling idle? haven't heard of people doing this before.. pfc doesn't throw a code for it?

describe your IAC and AAC (air regulator i assume?) elimination setup air plumbing and wiring..

are you sure the 0% duty cycle is what is causing the motor to die, or is it just showing 0% as a result of the motor stalling out?

have you tried starting it with the throttle partially open?

[OpeLok]

simple check. U said wiring. So check if you made a lil mistake at the eccs relay. Such as 12vdc constant now changed to 12vdc switched. Probe it with a volt meter. also, afm. Swap em out see how that goes.

I'll contact my wiring guy about this and see what he says. I'm giving him the harness back again.

Since you upgraded the injectors and MAF, did you change the appropriate settings in the PFC to match?

Yes, I have 5 options on the PFC.. doesn't matter which one I choose on the MAF setting. Also, when I parked the car and took it apart, all of these same components were running on the car.

Maybe not your no-start problem but it looks like you'd have a huge vac leak running your PCV like that.

No oil comes out of it, and it ran fine like this for a long while with no side effects

IAC and AAC eliminated seems like a pretty big deal to me. how are you controlling idle? haven't heard of people doing this before.. pfc doesn't throw a code for it?

describe your IAC and AAC (air regulator i assume?) elimination setup air plumbing and wiring..

are you sure the 0% duty cycle is what is causing the motor to die, or is it just showing 0% as a result of the motor stalling out?

have you tried starting it with the throttle partially open?

IAC and AAC connectors are just hanging out. It is still wired for this. To eliminate I just used a block off plate on the side of the intake manifold. For idle I just used the set screw on the TB. The injectors show 0% and the motor dies another second after wards. It's got plenty of fuel. Coil packs spark and ignite remaining fuel, but injectors are no longer powered. So injectors die out, and then of course coil packs after it runs out of fuel. I can set lag time and duty cycle to max, dump fuel into it, and run the car for a while. Of course it's running like ****, and injectors still read 0%. I should have also noted, (a bit short sided on my part) that this car actually will run off of a stock ecu. ****, the car even runs off an SR ecu. I've tried ROM tuning, and there were some issues with that. Basically the car wouldn't respond to the changes being made on the chip. Set rev limit to 2000rpm and it will still hit 8000 if I revv it that high. Idles well at 1000 nice and steady. Since the car isn't responding to the changes, it's dumping **** tons of fuel and after the car is shut off, the fuel pump fuse must be pulled, start the car and clear the fuel. The car will actually run without fuel pump for a minute. This led us to believe initially the Power FC was bad because it could run off of a stock RB20, and even an SR20 ecu. I tried the PFC on another working RB20, and it worked like a champ. No idea the difference between the two ecu's and what and how the interpret things. Again, I really really really appreciate all of the brainstorming going on. I'll talk to my wiring guy about the power to ECCS relay. I know he did something funky with the relays, but he assured me it would have no effect. Instead of 2 green relays, I now only have one.

[Carl H]

check your power wire for the injectors/sensors...its white/black.if there was an issue with it then it wouldnt switch power to the injectors properly and would have to backfeed to power them.also the way the car is wired its better to keep both relays to keep current load to a minimum, if anything converting to the brown nissan relay vs the green relays would work.

a quick test would be to unplug an injector and power the car on, then test the white/black wire found on every injector...it should have power key on.

[OpeLok]

I think we did that about a month ago, but I will do it again... got a new snap on test light, might as well break her in.

[OpeLok]

so it's been a while now, but tonight the headache has ended. Take me off of the NOn Running RB list. Basically what happened is the ground distribution block was full of corrosion. During its down time when I put the intake manifold on, I also had the harness re-done. Before it got to the person that was doing the harness a leaking a/c unit had dripped all over the car and exposed harness that was sitting on top of the engine ready to be pulled. Cleaned everything off the surfaces, no big deal. After literally months and months of diagnosis, ohm checks, pin checks, harness comparisons, the nightmare is over. Just in time for gas prices to be so high! hahahaa! My car has been down for 1.5 years. I'm fuc*king happy right now!!!!!!

[Kansei240sx]

First word of advice, dont ever, ever, EVER, use a test light for electrical diagnosis.

I was having a similar problem, it was a bad ground AS well as a shredded power wire to the injectors.

[OpeLok]

no, no test lights on anything. Always used a DVOM. We we're running an oscilloscope on this thing as well watching all of the sensors patterns that control ignition/fuel. There was continuity and everything... just not good enough of a ground for the Power FC to work. The factory ECU would work, and that's why it was so frustrating. I don't even own a test light haha

[Carl H]

gotta love bad grounds...make for a pain in the *** to diagnose.

[OpeLok]

haha, just re-read this thread and found out that I do have a test light. I totally forgot I had it! hhaha, It's done me pretty much no good Yeah, stupid ****ing grounds! hahaha