VL runs on 3 cylinders!! unplug 1 injector and runs on 5

[DOORMY]

Hi I am new and hope someone can help me with a problem .
Ok the engine seems like its running on 3 cylinders , I take
off an injector plug and it runs on all 5!! put the injector plug
back on and back to a very rough 3-4 cylinders, got me stumped,
Thankyou any help appreciated


I will try explain better !! The engine runs with all injector plugs on them , though
it runs as rough as guts and seems its running on 3-4 cylinders.
I can take an injector plug off of either 1 of the 6 injectors and it runs smooth on 5 cylinders.
Put the plug back on the injector and back to rough again. its like with all 6 connected it shuts
off a couple of injectors, but take 1 plug off and it activates the others !! dont know but it just happened.

[siroller]

beats me. i'd take it to a mechanic.

maybe its running rough because there isn't enough fuel getting in there and it's not igniting properly? i'd give it a full tank (to knock out the in tank lift pump... if the fuel tank is full and the lift pump isn't working the external pump wuill still provide enough fuel)

clean the spark plugs as i'm guessing they will look pretty rough after how it has been running, clean or replace the fuel filter then plug everything back up and see what happens.

my reasoning is that maybe its not getting enough fuel. by knocking out one injector there is one less to feed and suddenly there is enough fuel to run 5 cylinders... really odd i know but worth a shot.

[DOORMY]

Thanks siroller !!
I was thinking along the same lines last night wrecking my brain !!
the injectors need there 20-30psi or whatever !! and with the
whole six plugged up they are not getting it with a half working fuel pump.
and with taking 1 injector away , the pump may be able to keep up with the 5
But then I have recently changed the pump . I will give the the pump a pressure test
I suppose when I can get hold of one .

[nasty1]

Dont be a tite ass and buy new plugs.

Start looking at simple things first like testing leads.

My second port of call would be making sure the wires on injector plugs are ok first

[DOORMY]

Plugs leads all good all cylinders fire !! another example of whats going on!!
All 6 injectors connected , take number 1 plug off injector 2 3 4 5 6 fire
put it back on the engine turns rough as guts !! now take off number 2 injector
plug off and 1 3 4 5 6 fire , and number 3 off and so on , its like theres an issue with 6 injectors
all connected .

[nasty1]

Plugs leads all good all cylinders fire !! another example of whats going on!!
All 6 injectors connected , take number 1 plug off injector 2 3 4 5 6 fire
put it back on the engine turns rough as guts !! now take off number 2 injector
plug off and 1 3 4 5 6 fire , and number 3 off and so on , its like theres an issue with 6 injectors
all connected .

so where does the running on 3 cyl come into it?

[nasty1]

First check that the electrical system is operating correctly by listening for a clicking sound from each injector, then if you cannot tell which one did not click you then proceed by disconnecting each injector wire in turn and connecting it to a noid light ( a 12 volt light bulb with 2 wires ) , when you turn the engine over the bulb should flash mimicking the injector pulse.

If they are all good move on to the ohm meter test, check ohms against a known good injector if you do not have the specs or look for variation across all the injectors. Also check the injector terminals to ground, if continuity is detected replace.

you could use a Digital Voltage OHM Meter and measure the resistance across the terminals of the injector. make sure vehicle is off and key out of the ignition. if the resistance is not within specification(can be found in vehicle specific manual or through dealership) replace that injector.

[nasty1]

if you have a gregorys vl manual book go to page 82.gives you step by step to test fuel pressure at the fuel rail and you can test it at the low fuel pressure pump to.

i would suggest purchasing one of these books its the best thing you can do

[87RB30VL]

i would suggest purchasing one of these books its the best thing you can do

Best thing I ever did by far, the only car I didn't buy a manual for, was my S13

[DOORMY]

First check that the electrical system is operating correctly by listening for a clicking sound from each injector, then if you cannot tell which one did not click you then proceed by disconnecting each injector wire in turn and connecting it to a noid light ( a 12 volt light bulb with 2 wires ) , when you turn the engine over the bulb should flash mimicking the injector pulse.

If they are all good move on to the ohm meter test, check ohms against a known good injector if you do not have the specs or look for variation across all the injectors. Also check the injector terminals to ground, if continuity is detected replace.

you could use a Digital Voltage OHM Meter and measure the resistance across the terminals of the injector. make sure vehicle is off and key out of the ignition. if the resistance is not within specification(can be found in vehicle specific manual or through dealership) replace that injector.

Every injector has a pulse when 1 injector is removed so 5 injectors are working when 1 is removed !! I put the 6th plug on the injector and all
the sudden with all injectors hooked up it runs as rough as guts like its running on 3-4 cylinders !! I can take off any one injector and it runs fine.
well I mean alot smoother but all 5 are pulsating.

[nasty1]

Could be getting to much fuel...

Take it to a mechanic if not 100% otherwise your pissing in the wind

[Tree cutter]

It could be getting too much fuel with all injectors plugged in. If the vacuum hose has fallen off the fuel pressure regulator you will have high fuel pressure at idle so your engine will run rich. Pull a spark plug out and check to see if it is black from running rich.

[siroller]

deffinetly pull out those plugs to check for richness. I should have explained in more detail but you can tell a lot about how a car is running from the plugs.

I'd still be looking at any fuel blockages. that makes logical sense to me thats all. is the pump wired up ciorrectly? I haven't done it but my father replaced the in tank pump and couldn't figure out why the hell the car wouldn't run properly. he had it wired in reverse so it was fighting against the main pump....

other than that the vac lines on the pressure regulater is a good suggestion. you said the afm is properly adjusted?

[DOORMY]

Finally got the engine purring !! what I first done was remove the computer and swap it with my other vl computer
that is working fine in the other car. No change to engine at all, so I put the original computer back in.
Then swapped distributors!! again the same , no change still running rough!! so then I thought to put back the other computer
from my other vl, and guess what its running beautiful. At the end of the day I would imagine the CAS was stuffed as well as
the computer, because no change was made to the engine running rough using the computer and distributor separately!! both
had to be together to fix the problem, Luckily I had the other vl for parts. Thanks everyone for you input!! much appreciated.

[bachig24u]

step 1. disconnect MAF/AFM and start engine? any difference? note: it is normal for the engine to only rev to about 2000rpm.
step 2. disconnect battery for 10 minutes, unplug the 02 sensor in the exhaust, reconnect battery, start engine? Any difference?

Is the car turbo'd? be worth checking for air leaks.

With your experiments with injector unpluggin, you may have discover that 2,4,6 and 1,3,5 are connected together.
basically if either one from either batch is firing, this illiminates the ECU as a fault.

have you check the ECU for fault codes, sometimes they can help. dial the adjustments gently to the end clockwise (270deg).
the red and green leds flash.

ECU Leds
Turn Diagnostic selector fully clockwise then and start engine.
errors; 11=CAS, 12=MAF, 13=CTemp cct, 14=VSS, 21=ign cct, 23=TPS, 24=Neutral, 31=A/C (ignore), 32=Starter cct, 34=VLT-knock, 44=A/C (ignore).
a red LED is 10's and Green is 1's (eg. error 31 will be 3 red flashes and 1 green then it goes to next error if not then it repeats)
to reset codes, have reds on and turns diag selector fully clockwise for 2 secs and fully anticlockwise for 2 secs then turn off reds.

some codes are normal, speed sensor, neutral, A/C.

Also check nice smooth fuel flow from the fuel rail to the fuel pressure regulator, no pulses etc. (should be smooth like a garden hose after 7 seconds).
If it still pulses after a 30 seconds, theres a problem. If you try to put your thumb over the hose to block fuel coming out it should turn into an unstoppable fine mist.
when bypassing fuel pump relay, don't follow the service manual they are often wrong and you'll blow ECU pump circuit to another world.
only connections closet to driver and front of vehicle should be connected (terminals 30, 87 on relay).

let us know how you go.

buggar .. took me that long to write this, is it still fixed? often the CAS plugs corode causing intermittent issues. sometime heat related.
I'd like to know if the ECU still works !!! It's a little unusually to kill them both.

[Munz]

buggar .. took me that long to write this, is it still fixed?

What? 20 days to write a post? lmao

[DOORMY]

Thanks for the long post and your time doing so !! the car is still running beautiful !! just put some extractors on it and 2.5 exhaust !!
Changed the rear drums to disc with slotted discs all round !! hsv vt 18 inch rims!! going to put a 5 speed in it as I have 2 spare wagons which
one has the 5 speed! hoping to put an aero kit on it !! back bumper will have to be modified to fit my wagon !! lowered it a bit in the ass and doing the front
soon got the springs though. Want to put a thicker sway bar in the rear !! thinking a vn wagon one might fit !! heaps I want to do.