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Discussion Starter #1
Looking for some insight on what might could cause this issue.

First off, the motor is out of a jzx110 running a drive by wire delete and using a jzx100 ecu. 12lbs of boost running these mods: J-pipe delete, futurefab downpipe, twisted motion turbo internals upgrade, stock 370cc injectors, Aeromotive FPR set at 36psi in reference to atm. The motor is in a 1992 240sx (I have no idea where else to go for help).

The car is slightly rich idle at 12-14:1 on an AEM wideband. Once the car is driving the AFRs stay around 12 at cruise. Once the car goes from vacuum to 0 or 1psi the AFRs max out at 10 on my gauge and the car starts to break up horriblly until boost builds. After boost comes on the car runs perfectly at 11.7:1.

Codes 42 and 47. Speed sensor, traction control respectively.

Here is a list of what I have replaced/changed/done while troubleshooting:

New copper plugs gapped at .026
checked for boost/vac leaks
TPS
ECT coolant sensor
O2 sensor
MAF
Knock sensors
Camshaft and crankshaft
Timing twice
Ignition coils
Plug wires
130amp alternator
340lph fuel pump with 12v mod
ECU looks good, no leaks or burns.

Any ideas? This has been going on for months and is driving me crazy.
 

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Try another ECU. Are all the plugs black, or certain ones?
 

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Discussion Starter #3
Try another ECU. Are all the plugs black, or certain ones?
I'm in small town arkansas or I would try another ecu. I'll pull plugs again and report back. First time I changed them they were all black. I have also had the injectors cleaned and tested. Using a new wiring specialties engine harness as well.
 

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I'd definitely go through the wiring harness, too. A continuity meter from plug to pinout.

Takes 30 minutes max, and you know for sure.
 

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That, I won't comment on because I haven't used a factory ignitor in ten years.
 

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Discussion Starter #7
So it is definitely overfueling. Just threw new plugs in, gapped at .026 and I lowered the fuel pressure down to 22psi in reference to atm (where it idlesat 14.7:1) still maxed out at 10 under slight load where it used to hang but no longer stumbles and was at mid 11 to mid 12 during boost.
At this point im really thinking the injector control might be a little wonky from the ECU but it looks absolutely mint on the inside. I'll check continuity tomorrow once my neighbors are awake.
 

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I just use a blank pin connector on a long wire into the car.

I'd prioritize the check with things like TPS, MAP, AIT, and such.

When Tweak did my harness, he had the TPS swapped around backwards and totally didn't install the ECU ground. Easy fixes, but I recently stripped that harness to build my new one.
 

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TPS could also be out of adjustment. Just throwing the regular checks at you.
 

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Have you had a chance to check the TPS or anything else?
 

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Discussion Starter #11
Yes sorry about that, I just rented a new shop so my house and garage could be cleaned up and all my projects can be moved.

So Ive had a hard time finding any writeups on what the jzx110 4 pin TPS is supposed to be set at. Only thing ive found is the 1st and 3rd pin should have a resistance of about .45kohms with the throttle closed.
The TPS is new and set right in the middle which is at .45kohm. I also moved it both ways to see if the adjustment would help. I had also extended the piping between my filter and MAF sensor (which is new) incase turbulence was an issue. Both had little to no change. Unplugging the maf the car runs absolutely horribly. I have about 3ft of exhaust right after the o2 sensor currently and will be hooking up the rest of the exhaust tomorrow once it gets in. I was wondering if it would throw off the o2 reading enough for the ecu to run full rich. Rechecked ecu for any leaking caps or flaws. It is seriously the cleanest ecu I have seen. Looks factory new on the inside.
 

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Discussion Starter #12
Got it!!!! I tracked down someone at a drift shop an hour away that happened to have a JZX100. I took my ecu, igniter,. and MAF down there with me. Everything worked fine until we swapped MAFs and it could barely stay idling. The MAF I had was brand new factory lexus/toyota and I guess was just a lemon. Anyways, ordered a known good and it will hopefully be here next week! thanks for the help. After months and replacing almost every part it ended up being one of the parts I replaced also being a bad noodle.
 

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I have a similar setup & problem on my s13. Pretty sure you need a JZX100 MAF to go with JZX100 ECU, cant use JZX110 MAF. Was your problem fixed?

With mine Im running 9.5 rich at WOT and running into fuel cut at WOT/high rpm. I have a full JZX110 setup. Fault codes 42/46/62/63/65/68/75/76/77
 

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Discussion Starter #14
I have a similar setup & problem on my s13. Pretty sure you need a JZX100 MAF to go with JZX100 ECU, cant use JZX110 MAF. Was your problem fixed?

With mine Im running 9.5 rich at WOT and running into fuel cut at WOT/high rpm. I have a full JZX110 setup. Fault codes 42/46/62/63/65/68/75/76/77
Sorry for the super late reply, I had a brand new OEM jzx100 maf which was bad from the factory. I replaced it with a new one and solved the problem instantly. Able to figure out your over-fueling issue?
 
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