240 missing, weak, runnin on 3 cylinders

[specialedd]

i have a 93 240, it started out occ missing but has prgressed into all the time now. it is getting fire, has new plugs n wires. it seems not to b getting the positive groung from where ever to open injector. it changes injectors from time to time, started out it was #2, then 4, then 3, now its 1. i can pull plug wire off n nothing changes but can hear it arcing. idle is rough and car shakes excessively when stopped in gear. computer is throwing trouble code 34 which should be the knock sensor. i swapped it out wit a friends used 1 n it didn fix it. any ideas on what it cld b wld b greatly appreciated.

[93240cooool]

try the techical forum.

[nissans13240sx]

Its an injector most likely. Ohm test them they should all be around the same reading.

[specialedd]

i tested the injector for power before, found constant hot, but no ground. i figure the ecu sends the groung to the injector to make it open. not getting that ground.

[roadboy240sx]

it is an injector or an injector o-ring, trust me it happend to me a while back

[Shabbernigdo]

on my car when i was having a similar problem one of my ground wires that are up inside that black case that sets up over the intake mani was was messed up it was worn through and was making a bad connection and my no4 injector was bad.after i fixed that i havent had the problem sence.

To be a bit more clear the wire was more toards the front of the engine.

[nissans13240sx]

i tested the injector for power before, found constant hot, but no ground. i figure the ecu sends the groung to the injector to make it open. not getting that ground.

You cant really test for injector pulse without an oscilloscope. If you use a dvom to check power it will just show constant power because it pulses to fast for the meter to read. Use the OHM feature if there is one, disconnect the injector and touch your leads to the 2 prongs on the injector. Do that to all 4. they should be in the same range about.

[specialedd]

wld 1 injector bad cause all 4 to act up? right now it is #1, but all 4 have done it. i have been chacing it dwn, n never knw which one its gonna be. i figure it wld b something that all 4 injectors share or have in common.

[nissans13240sx]

Maybe fuel pressure regulator is leaking? Pull off the vac line to it and see if theres any gas in it. Also try swapping out the ecu with a known good one.