Tuned By Jake

After some major headaches trying to figure out what the deal was with Javier’s Corvette I finally figured out that there’s a few things different about the LS3 MAP Sensor.  Apparently the new LS3 uses a different sensor/location/pinout compared to the earlier LS1/LS2-based applications.  The sensor is now moved to the front of the intake which likely gives a quicker more accurate readout of manifold pressure, and the pinout for the sensor is different. Wiring the new LS3 plug directly into the old pinout will produce a static 21kPa readout in the PCM which will of course not allow the car to crank up and run right.  When wired differently the MAP readout is entirely wrong and doesn’t produce an accurate reading in the PCM.  At atmosphere (motor turned off) the sensor will read out 84kPa which is definitely not right.  Once the engine is at idle it surges and won’t stay in a single cell, it’ll skip around to several cells way beyond the range it should be in.  I did some research last night and figured out that Katech makes an adapter harness, but I’m not sure if it’s a straight wire harness or if it’s got resistors in it to make the voltage readout similar to the LS1/LS2 sensors.

Anyways, after messing with the LS3 sensor a lot we still couldn’t get the engine to idle right and finally I just figured to wire up the stock LS2 sensor and make it fit somehow in the larger LS3 MAP hole.  Once we wired it up everything was as smooth as silk.  The motor cranked perfectly, idled just right with a little chop, and the throttle transitions were much smoother and quicker.  This weekend hopefully with some better weather we’ll make sure topend is where it needs to be. We should get some nitrous numbers soon too with Javier’s setup!