Rb20 breaking up in boost, lean!

[92R32GTST]

My rb20 smells rich at idle but when getting into boost around 5psi it starts to cut out and break up. Spark plugs show that it is indeed lean. White color.. Anything to check? In time. New plugs gapped at .08, what could it be?


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[h4X6]

Fuel pump. Check that. Fuel filter. Best places to start

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[ToroGTS]

Lean conditions from fueling (weak pump, clogged filter orinjectors ect.) tend to present through a detected knock event. The car will still rev out and be audibly smooth, but have a total loss of power at some point during boost. Looking at it with the benefit of standalone (or nistune) and software, you will see the timing massively retarded at the moment of this power loss.

What you are describing is more than likely ignition related, in particular weak coil packs or a defective Cam Angle Sensor. Check your coil packs with a ohmeter across the + and - terminals (they are marked), should be seeing 0.6 - 0.9 ohm resistance. If they are out of spec replace them with OEM or better yet, convert to LS2 coils if you are running lots of mods (big turbo, injectors, intercooler, intake & exh). Another likely cause for high RPM break up is corrosion of the 12 v power feed or grounds in the OEM ignition harness. After 20 + years the wiring begins to break down all over these cars unfortunately.. CAS missing at higher rpm is usually harder to pin point, best to try swapping with a known good part to rule it out. May also be worthwhile to check calibration or just straight up replace the TPS sensor. I've had issues with original TPS's even though they read correct calibration, due to worn out idle contact pins within the sensor.

[Skym]

Lean conditions from fueling (weak pump, clogged filter orinjectors ect.) tend to present through a detected knock event. The car will still rev out and be audibly smooth, but have a total loss of power at some point during boost. Looking at it with the benefit of standalone (or nistune) and software, you will see the timing massively retarded at the moment of this power loss.

Correct, but not power loss, torque loss. The torque graph has a big V shape in it when stock ECU pulls ignition timing. Power graph looks normal, but power graph is derived from torque (what the dyno measures) via a formula.

[92R32GTST]

Car now has new filter and another Walbro 255, 40 psi pressure to rail and plugs all gapped good. Timing is dead on...


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[92R32GTST]

Break up is at 5-6 psi so low to mid rpm


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[ToroGTS]

Throw a new fuel filter in for good measure and take the resistance reading on your coils.