oblio

ok- i think that my last post was too long - heres what i need to know:
does the barometric pressure sensor tell the ecu how much boost your car is making? my stock gague isnt moving up past like 10mmHG, but i know by connecting a mechanical gague that my car is making ~9 lbs of boost before my wastegate opens. is this causing my ecu to starve my car for fuel under boost? any time i boost i hear detonations (or, i think i hear detonations). my compression numbers are still good, but i am afraid to go give the car boost. sounds like a clicking or a popping coming from the injector side of the motor. i have tried to replace the Baro. Press. Sensor - with no results... is this an ecu problem?

oblio

PS. i also replaced the fuel filter - o2 sensor, and checked for vac. leaks. replaced my plugs and triple checked my plugwires to make sure that they werent crossed.
the car is relatively stock - 40K on a rebuild using n/a center iron, one-piece apex seals, straight piped with stock mufflers, emissions removed, turbo switching actuator removed.
any help?

NZConvertible

If you mean the manifold pressure sensor (in the engine bay), then yes it does. The atmospheric (barometric) pressure sensor is under the dash.

No, the ECU's main load sensor is the AFM, not the MAP sensor. The MAP sensor does contribute to fuelling and ignition timing in minor ways, but if the ECU is receiving a reduced MAP signal you would still be safe uness you were already right on the edge of detonation. That's how FCD's work.

The best way to check if the ECU is receiving the right signal is to measure it. Use a DMM to measure the voltage on pin 2B while driving. At 9psi it should be about 3.7-3.9V.

ECU pins: https://www.rx7club.com/attachment.p...hmentid=165722

With your mild mods you should not get detonation. Possible causes are incorrect timing (check it), very high intake temps, low octane fuel or a combination of these things. Are you sure it's actually detonation?

oblio

no, i am not sure... i have never heard detonation before - what i do hear is like somebody is whacking the firewall with a wrench, sounds like a backfire within the manifold? or something like that. when trying to time my car i have had problems because my high tension leads are soo thick, that i cant get a steady blip with my timing light... this brings up another issue - when i have the timing light connected, and the cover off the crank angle sensor, i see it blipping usually when the main (180 degree, and topmost) part of the rotor is hitting the magnetic sensor. then, occasionally, i see it go off by 90 degrees for a second or two, then come back. it did this with both of the crank angle sensors that i have.
lastly - i think i am confused - despite the sticker on the sensor (map sensor?) that is on the pass. side strut tower which clearly reads "barometric pressure sensor", i guess that is something else. when i remove its vaccuum, my in dash gague does nothing...
thx nzconvertible for doing the research on pin voltage, ill hook it up to a good voltmeter and measure it.