candrade

Hello. what causes this besides a bad ecu? distributor, tps, afm?
I have voltage in all 6 injectors but no ground at injectors #2 and #5.
thank you.

ES300NZ

what on earth are you on about ?

the injectors are given switched power from the main relay, they are earthed by the ecu as they need to be fired. Your question makes no sense.

candrade

yes, i know that. im asking what makes the ECU to not send the ground signal to just 2 injectors? i suppose the ecu determines when to fire them according to sensors

ES300NZ

the ecu doesn't send a ground 'signal' anywhere. It switches a wire to ground.

could be alot of things. dude, .. how are you testing for this ? because I'm smelling inexperience.

candrade

with a noid light. 4 injectors are being fired by the ecu. injectors #2 and #5 are not.

ES300NZ

ahhh ... you've misunderstood the test.

candrade

Ok, so what does it mean when 2 injector connectors doesnt pulse when the noid light is connected and the other 4 do?

LeX2K

If you have the noid light connected inline with the injector then it could mean the injector is shorted out. If not inline and no signal then either bad harness or bad ECU.

candrade

the noid light was not inline with the injector. just the connector.
does the ecu take input from sensors (tps, afm, vss, distributor, lambda) to fire or not fire individual injectors?

ES300NZ

ECU's aren't that smart. even on brand new cars they are programmed to either fire all the injectors or not at all. I could list the conditions in which they won't fire any injectors but it's long and boring.

to answer your question simply, the ecu either sees the conditions in which it should fire all the injectors or it does not.

IF you have an ecu fault (and I'd be a suspicious that you might), then you've lost an injector driver in the ecu (it's failed), which would explain why two cylinders aren't firing, because the injection is paired in that year range (not sequential). You'd need to work out if those injectors are paired.

That's easy enough to do, do they have the same coloured wires running to them (not the striped wire), solid colour.

LeX2K

The 3VZ is a sequential multi-point system see here for a technical overview

candrade

Can i wire the 2 injectors that the ecu isnt firing to some other injector?

LeX2K

Doing that will double the load on the driver transistors. You need to test the resistance of all the injectors to make sure none of them are shorted out.

candrade

Ok, ill check the injectors. So, can i buy the driver transistors and make someone experienced in soldering to replace them in the ecu?

ES300NZ

you would think so, but the next like down says " The fuel injection system has 3–groups injecting to
two cylinders each. "

so, that means the ecu has 3 injector drivers, which it uses to put fuel in 6 cylinders, in pairs of two.

which is paired injection, which would make sense, cos Toyota didn't go sequential until something like 1997, or 1999 (well after 1995 anyways).

so, .. not sequential at all. well, .. not in the sense we would use it.