bassmaster5000

Hello All, I have lurked for a while know, reading up on different posts, but I have not been able to find the solution so I figured I would start a thread. Back story; I have a 1990 240sx (originally a single cam, automatic car) that I swapped in an RB20 using Zero Point mounts, and an OEM series wiring harness from Wiring Specialties. Car was tuned for 440cc injectors, running a Z32 MAF, and a T04E on 17-18lbs of boost. The RB I bought came with a top mount manifold, the T04E (that needed to be rebuilt), LS2 truck coils, and a Freddy Intake. I got the motor put in with no issues (other than the mounts setting the motor a couple inches back so I needed a custom driveshaft), the wiring harness plugged up, the battery relocated, front mount hooked up on the car, vacuum lines ran, etc. Went to start the car for the first time, fuel pump wasn't priming. No big deal, just put a jumper in the relay to get it going. Started the car up, and the idle was very high. Started to go over my wiriing, and noticed that the MAF was unplugged. I plugged the MAF in, went to restart the car, but the car wouldn't idle. Car would run rough, sputtering around ~600 RPM until it would die, after 5-10 seconds. I have read a ton of posts, trying to fix the issues. So far, I have tried..
-Replacing the MAF (tried two different working MAF's with no difference)
-Tried trouble shooting the TPS, checking resistance and voltage (even tried installing a known working TPS, and setting the TPS voltage to .45-.5)
-I pulled the AAC, cleaned it, and tried reseting/adjusting the idle screw, with no difference
-I have tried unplugging the AAC, does not change anything
-I have checked for vacuum leaks (only leak would be open air breathers I'm running on valve covers, but even plugging these does not change anything)

I can keep the car running if I feather the throttle, but as soon as I let up, it never "catches" idle, it just bogs and dies. One thing to mention as well, I was testing everything with a GT3071r, instead of the T04E. I had someone holding the idle around ~1000 RPM the other day, while I was checking for vacuum leaks. I noticed that the car started to smoke a little bit, it was burning oil. I turned the car off, pulled the down pipe and intercooler piping, and had a bunch of oil in them. I checked the drain to ensure it was properly draining by pouring some oil into it through a funnel, and there was no problem. I am using a restricted feed, so it led me to believe the seals are bad on the turbo, or that I'm getting horrible blowby, even just at lower RPM. I ended up picking up a rebuild kit for the T04E, so I just pulled the 3071 and through on the rebuilt T04E.

I hadn't messed with the car after rebuilding the turbo, until today when I finally got my consult cable in. I downloaded ECUTalk, free verison of Conzult, and two other programs (Nissan DataScan and Scan Tech I believe), but could only get ECUTalk and Conzult to work. I checked out each program, and tried to check the readings on most of the senors, verifying them off info in the FSM / different forum posts. My TPS was reading around ~.38V through each program, so I adjusted it up to ~.44V, at closed throttle. At wide open throttle, its reading 4.10V. One of my Z32 MAF's was reading around ~.57V, but my girfriend said that it was bouncing around a little when I would attempt to crank it, or even just in the key on. I swapped it with a different MAF, voltage at key on is .5V. Looking at the "duty cycle" of the AAC valve, during cranking it would shoot up to around 80%, I'm not sure what this should be at. My timing said that it was at 16*. Temp. Sensor was giving a reading of around 84* F, which is ambient temperature. I'm sure there are other's I am missing, but I cannot thing of any right now.

I pulled codes again for the heck of it, the other day it had said no faults. This time however, I pulled Code 21, Ignition Signal. I did a quick google, saw plugs could be a problem, swapped them out, cleared codes, tried to start car, nothing. Pulled codes again, still Code 21. I checked all the connections on my LS2 coils, everything felt good, checked the coil plug on back of motor, igniter plug, spark plug wires, etc. Cleared codes, Code 21, wont start.

For the heck of it, I unplugged the MAF again, and car fires right up immediately, Idle jumps really high. I turn it off, plug the MAF back in, car wont start. I'm super baffled, I can't even get the car to idle right now while giving it gas, it seems like it is missing ( which doesn't make sense, when I pull the MAF it doesn't sound like it is misfiring at all ).

Any help would be appreciated, I haven't seen much on the forums about what Code 21 could be. I checked the FSM, not a whole lot of info in there as well. I'm starting to think that the ECU may be the problem, but I'm really hoping that isn't it. Sorry for rambling, I tried to post all of the pertinent information that I could think of.

bfellini

There are potentially so many issues here, you need to read through the FSM and trouble shooting the basics...

What ECU are you running, and if it is "tuned" for a particular setup, you need to have those components installed... do you have the 440cc injectors?
LS2 coils have internal ignitors, so no external (stock) ignitor is needed, and the dwell settings are completely different from any of nissan's offerings.. If your ecu is not setup for these coils, I would revert back to the stock RB20 coils and ignitor... an OEM WS harness will not be correct for LS coils.
Also, I suggest you hook up your PCV system properly, and re-check for vacuum leaks for starters. I would recommend double checking all vacuum lines, and smoke testing your motor.

The fuel pump should prime at first Key On Engine Off, and the fact that it doesn't, points to a wiring issue... remove your hard wiring hack, and trouble shoot why the pump is not priming by probing the ECU fuel pump output pin directly for ground (with a multimeter set to continuity) when you first turn the key to "ON". If the pin doesn't ground for several seconds during the pump prime period (usually the first 3 seconds after the key is turned to "On"), there's potentially an ECU issue. If it does show ground via probing with a multi-meter, then there is a wiring issue in your chassis.
The FSM is your friend, as Im sure you're finding...