Simpson

car was running , died suddenly


have 12 volts to igniter, coils have resistance of .2 ohms
crank angle indicator has 150 ohms
fuel pump works on starting
ignition switch checked out


15 amp fuses good under drivers dash
engine fuses like egi good


But no spark

satch

iTrader: (1)

Check the Brown/White wire of the TPS w/key to on as it should read 5 volts. If it is close to 0 volts then there is a short in the system (likely the AFM).

Simpson

thanks satch

i found 10.5 volts on the brown and white (from wire to ground)
Do think it might be the ecu ?

satch

iTrader: (1)

Just for kicks check the same wire at the pressure sensor and also check the Black ground wire at this sensor (both w/key to on). First wire should have 5 volts and the ground right near 0 volts. You 'might' have a grounding problem as opposed to an ECU issue.

Simpson

At the pressure switch the brn/w wire had the 10.5 volts . And the black had 8 volts. so I would say there is definitely some voltage shorting into the black.

the wire harness has had a lot of patch work done in the past (.seven blue crimp connectors.) I will investigate further . I am going to do a motor swap soon , might get a better inspection of the wire harness when the motor is out.

thank you for the insight
Simpson

satch

iTrader: (1)

The pressure sensor has 4 wires. One wire is solid Black and that is the ground. There is also a Black/White wire which is supposed to supply 12 volts to the sensor. If you are measuring the proper wire, the ground wire (solid black and not Black/White), then you have a grounding problem. If the main engine ground were disconnected from the engine block it would have 12 volts w/key to on (speaking of the ground wire at the sensor). Since you have close to that i would say the main ground is not properly grounded and that is why the solid Black wire you measured has the voltage that it does. There are a series of ground wires at the ECU. Pins 3A, 3G, 2C and 2R are all grounds (some of these are tied to each other). Pin 2C supplies the ground to the engine sensors such as the pressure sensor. If you backstabbed this pin at the ECU w/a wire which is grounded then it should drop the voltage on the Black wire at the pressure sensor to 0 volts w/key to on. Also, if you set a multimeter to continuity followed by placing one meter lead to the Black wire you measured and the other lead to a ground source (negative battery terminal) then the meter should ring out signifying the wire is grounded. If it doesn't ring out then it tells you the ground wire is not grounded.

kardoktor1

you could also "as a test", install a second or redundant ground to your sensor ground circuit, As a temporary test/fix to see if your headed in the right direction.

Simpson

spark is back

I did a motor swap and after fixing up wire harness. and finding a loose connection to air flow meter. the spark is back

thanks to all for help