Drivers side Injectors are dead!

[Dog House]

My 89 was running on four cylinders apparently do to the vats?
I had to put a new ignition cylinder with a chipped key. The old one was a generic cylinder with a non chipped key.
The chip I found under the hush panel with the two vats wires held on to it with a clamp. After putting in the new ignition I got the left bank injectors back and all was good. Drove the car to work the other day and service engine light came on. I ran a scan when I got home and had cod 42 which I forgot to clear after setting the timing so I cleared it and went in the house. Went to drive it to work the next day and it was back on four cylinders. What is causing the drivers side injectors to go dead? ECM?

 

[vetteoz]

Nothing to do with VATS.
VATS takes out all the injectors , not just one bank.
Check the injector fuses ( one for each bank ) then ohm test the injectors.
One shorted injector will cause the ECM to shut the whole bank down
If that checks out you may have a bad wire / connection/ short on the control wire ( black ? ) to the ECM from that bank only.
Injectors are grounded at the ECM to pulse them so at injector plug you should see 12V on the pink ( key on ) and nothing to ground on the black

 

[BADDUCK]

I'm gonna bet it's a shorted injector. May ohm out in the 3 to 4 ohm range.

 

[Dog House]

I should probably add the fact that all the grounds at the ECM are tapped into with the blue wires and all tied together with the red wire nut shown but not sure why. Where is the main ground at?

 

[John Robinson]

ECM Ground

On my 93 the ECM main ground is attached to a stud on the bell housing with two other grounds. If I were you I would sit down and trace each of the blue wires to were they interrup the ground they are attached to and remove them. One thing I just discovered when I was trying to trace a knock sensor wire was that between the knock sensor and the ecm there must be several other circuits depending on input from that wire. In other words the ECM must look at each wire and circuit and decide what to do something like this. If the ecm senses (A) happening then It must look for (C) and if (C) is correct then It will check (B) etc. That is an over simplification I am sure but what it tells me is that the wires going to the ecm are not stand alone in there function. What I think is happening to you with that wireing is that since they are all hooked together they may be confusing the ecm with signals from other circuits crossing over were they are all bundled together.

Good luck and again before spending a lot of money on enjecters and other parts get the wireing right and I will bet your problem will be solved.

 

[vetteoz]

I should probably add the fact that all the grounds at the ECM are tapped into with the blue wires and all tied together with the red wire nut shown but not sure why.

The injector grounds are not chassis grounds.They go straight from the injector plug to the ECM and are then grounded by the ECM to the ECM main ground.
A DVM on the inj ground wires ( at inj pug ) should not show a connection to ground

Inj 1357 Blk / Pink Terminal D15 @ ECM
Inj 2468 Blk /Green Terminal D16 @ ECM

Bottom two wires in RH column of pic