Can anyone tell me what the sensor is near the back of the plenum, on the bottom, on my 89 L98? Also what years were map sensors used?
Thanks
-Gabe

 

That sensor is the Manifold Air Temp sensor. There's a sensor identical to it on the front of the intake which is the Coolant Temp Sensor...both sensors are actually the same part #... how nice huh

Not sure on the map sensor question... someone else might be able to help you with that.

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1986 Trans AM
305 TPI
Well over 200,000+ miles (speedo/odometer non-funtional! Odometer reads 142,000)
4 Wheel Discs
9 bolt Borg Warner Rear (2.77's....oh joy) :P
Completely Stock
Current Project: upgrade to a 355 TPI, 6" rods, 9.7:1 Compression, Stock TPI ported, 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech hot coil.

 

The Speed Density system uses the MAP sensor. The SD was introduced in '90. Some, I'm not sure all, have the mounting in the rear for the MAP. Funny how GM went to SD from MAF, and F#RD went from SD to MAF. Although there is a bit of HP increase with the SD, because it is more rigidly mapped. That is why it is less forgiving to mods. The best system would be to use both MAP, and MAF.