eCtune

I have a 1989 Honda Prelude 2.0SI with a B20A5. -9:1 Wiseco Pistons -Bisi Rods -Stock head, intake mani, and head -WeiRtech Tubular Turbo Mani -Precision SC61 -Tial 44mm WG -Tial 50mm BOV -Precision 880cc Injectors -Hondata 4bar map -Ostrich 2.0 and Hulog Basically my problem is that the map sensor stays at about .30volts. I tried putting a good oem one in and the same thing. It sticks on the lower vacuum portion approx 24 in/HG. I have ohm'd the wires out from ECU to map sensor and they are good. I have checked the hose and it is in good shape. When I unplug the sensor it goes straight to 4.8volts and no code is thrown in ectune. I have had the car running for a few minutes here and there with some crazy fuel settings, but didnt have datalogging on. Now I can only get it to run for a few seconds. I am at a loss for what else to try. My vacuum/boost gauge was reading the changes in vacuum, but nothing in ectune, which I verified with a voltmeter. Any help or ideas would be great. Thanks.

make sure all the wires going to the map sensor are good. You want to check for continuity from ecu to the plug on the harness. Make sure your getting voltage on the wire your supposed to be etc....

I checked continuity from ecu to harness and the wiring is all new. I get 5volts on reference and the ground is good. Is it normal to be reading 5volts on signal with the sensor unplugged?

Sounds like a faulty map sensor if it's sticking under vacuum... I had a map sensor issue I had to fix once, instead of a throttlebody gasket they used sealant and plugged up the map sensor port. Check the map sensor's vacuum source; make a temporary alpha/n indexed map so you can run without the map sensor to check vacuum

I was thinking faulty map as well and then I tried an OEM one, but I guess I cant verify that it is in good working order, so maybe thats it. I will try AlphaN. I am out of town for a week and I will see what I can find out. Thanks.

faulty map sensor +1

Bad ECU?

Simple diagnosis... 1) Check output voltage from MAP sensor using a voltmeter. 2) Apply controlled voltage to MAP input on ECU (for example bridge the input to TPS for the duration of the test). Check MAP input voltage in eCtune to see if input is working. /Allan