Super Strange Injector Troubles

[pablo_max]

First I would like to say thanks for the feed back I got on my non-starting troubles.

Heres the deal with my non turbo 1983 280zx:I took out all the injector and gave a good cleaning. I cleaned out the throttle body and the intake manifold as well. I replaced all the hoses and tubes I could and then I put it all back together.Before I put it back together I had sprayed a bunch of carb cleaner into the intake manifold and the injector holes to clean them out. When I tried to start it back up, it fired right up, BUT died after about 10 seconds. It was clear that it was only burring what was in the manifold and cylinders at the time. Then of course, it would not start again.

Now, heres the strange bit...the number 6 fuel injector holder was cracked, so I thought that perhaps it was leaking somehow..so I unplugged the electrical connector on the injector and tried to start it again. Started right up and stayed on. Great I thought! I must have a bad injector. But just to make sure it was not some fluke, I unplugged number 5 and plugged 6 back in. hmmm. Still on. Now if I plug 5 back in, it dies straight away.I noticed that as long as I unplugged any 1 injector the engine stayed on.Now once it would die the fuel pump stayed on..(I heard that was an indication the AFM was working)

Can this be an ECM problem?I am really stumped on this guys.. Any ideas on this?

Best regards,

Patrick

[evildky]

that is wierd, did you check all your other connections? check the CHTS and the afm connector

[pablo_max]

Ok, stupid question...what is CHTS?

I didnt take the AFM off, so the connector should be fine..also it does not seem reasonable that the AFM would shut it off directly...I would imagine that if it were a sensor of some kind it would run like crap, supper and die rather the it being almost as if someone just turned the key off no?

What a grounding issue? I dont have a drawing of the electrics, but can it be that somehow connecting all the injector wires somehow makes a short and turns off all the injectors?I also unplugged a 2nd one while it was running at it increased the idle by about 50 rpms...\I told you this was strange.

Best regards, Patrick

[evildky]

CHTS= Cylinder Head Temp Sensor, it's either at the base of the head on the passanger side between I believe spark plugs #4&5 (might be 5&6 but I'm too lazy to go look, or on earlier cars it was located in the lower thermostat housing, it'll be the connector with 2 wires

the afm tells the pump to come on and stay on, if the afm gets stuck it only primes the fuel lines then shuts the pump off, might be kinda dumb but thats how the bosch L-jetronic injection system on the z's was made,so you'd have adequate fuel pressure for startup then when it ran out it would die, and bad afm or just bad afm connector contacts have been known to casue all kinds of wierrd problems

as for the injectors, they do not use a ground, theyu use a square wave disconnect signal, basically constant hot on one side and disconecting hot on the other side

as wierd as this p[roblem seems to be could also be a bad ECU, is your car turbo or n/a?

[pablo_max]

If the AFM was bad, I would assume that it cant keep running with 5 cylinders.

I dont have the drawing for the electrics or an O-Scope so I cant check the wave on the plug. I did notice however that the two wires have continuity between them and also both have continuity to ground. Should this be the case?

I did notice that there are two ground leads coming from wirewrap that has the injector wires.

Does anyone know what the amplitude of the wave should be?

[pablo_max]

Is there any chance that someone with a multi-meter can check something for me??the bottom electrical connector on the distributer that goes into the fuel injector wireloom on my car has one of the wires going to ground and i dont know if that should be the case. Can someone please confirm that for me? Now, I dont know what the part is...it behind the fuel pressure regulator towards the driver wheel well and to the left of the throttle body (under injector wireloom) it has a electrical connector on the side towards the radiator and a blue/white and blue/yellow wire on the other side....When I disconnect the blue/white wire, the short to ground on the connector on the distributer goes away. is that normal?Can anyone help with this?

[evildky]

so I ma to assume that we're dealign with an N/A car which I am not so familar with, the connector on the manifold you describe sounds like either the cold start valve or the cold start injector depending on what the n/a of that year came with

the distributor on the n/a is I believe a variable reluctor so the 2 wires coming from the black box should trigger the ecu, which in turn shoud trigger the spark, does the n/a use an ignitor next to the coil?

[pablo_max]

I am not sure if it uses that actually. Next to the coil there is nothing though..just the coil...although the distributor has a couple things bolted to it.\

I am also not sure if it a cold start injector or not. I only know that it has a bosh connector on one side and two wires for power on the other...along with a hose which goes in one end and out the other. I got a spare AFM and i will stick that in and see if it makes a difference.

[pablo_max]

ok, its actually the coolant temp sensor that i was thinking of...the blue/yellow wire on it has a ground and when i plug that in, the distributer bosh plug gets ground as well...is this normal?

[pablo_max]

ok, now it's running. It was a pinched wire near the ECU.

New problem, but i will make a new thread for that.