surging problem

[VQXTC]

Hi there all

Have a surging problem with my vl commodore which is duel fuel.
hitdrivingdrivingWhen i hit 2800 rpm the tacho needle flickers from 3000rpm to as high as 4500rpm just as i reach the 3000rpm mark at the same time the car surges until it hits 4000rpm then its fine.
It does this more on gas then petrol, however can do on petrol as well.
Have had gas system checked and is all fine.

Any help on this situation would be greatly appreciated

Cheers
Simon

[dan_man31]

had the same problem with mine changed plugs leads and plugs and cleaned throttle body problem went away although mine wasnt on gas but seemed as though mine was struggling to get to 4000 with needle flicking also

cheers Dan

[VQXTC]

Hi there dan thanx for the reply a recent development, I was driving home last night from work and it back fired when i went to put the foot down just prior to that it still chugged and surged. Scared the Sheet out of me....
So i am wondering if its got something to do with the computer receiving the wrong signal from the engine.
Is there anyway i can check the computer for fault codes???

cheers


SImon

[dan_man31]

yeah look it up on Google there is a way you can check the computer but that sounds a lot like air flow meter possibly an air leak between air flow meter and the throttle body or possibly a dud unit i had mine replaced couple of times but it seemed to backfire and chug and struggle almost to the point where it was undriveable car should be slightly rough at idle if afm faulty but again best way to check is to look up the fault codes and diagnose it that way i think i saw a link on here on how to check the computer

also its easier just to replace your air flow meter unit but there is a way to repair them sometimes cheaper to fix it

best way is if u have a friend with another vl ask to borrow his afm unit go for a drive and see if it makes the difference

cheers Dan

[VQXTC]

Hey there dan, I popped the bonnet today to find..........an airbox in a thousand pieces. The back fire that i heard last night was the sound of the airbox exploding........... I also found that if I wiggled the cas plug on the top of the dizzy while the engine was at idle that it started misfiring and surging even at idle and prior to the back fire i wiggled a few plugs and that was one of them. Which of course made it worse i have a new cas kit with the dizzy bearing so i might have a go and fit that tomorrow.......do you know of anyone that may have done this already. (never done one....)

Thanx for the info so far......

cheers

simon

[dan_man31]

far out that sounds pretty wild i know its a common problem with the vn's with the crank angle sensor if your air box is broken then its definetly a combination of your afm getting a faulty reading due to the back fire from the cas

just looking in the repair manual it has directions on how to replace the cas ill write it out hope it helps

1. the crank angle sensor could be regarded as the right hand to the ECCS control unit, as it is the basic signal sensor for the entire ECCS system. it monitors the engine speed, piston position and it sends signals to the ECCS control unit for control of the fuel injection, ignition timing , idle speed, fuel pump operation and the EGR function.

renewal

1.remove Distributor
2.remove the rotor retaining screw and remove the rotor
3.remove electrical connector screw and remove connector
4.remove the crank angle sensor dust cover screws and lift off cover
5.wrap the distributor gear with a rag and place in a vice to hold
6.put a screwdriver into the rotor shaft and remove the screw then the shaft
7.carefully lift out the rotor plate
8.lift the rotor plate positioner and not the wavy spring located between the positioner and the rotor plate base plate
9.remove the three retaining screws and remove the crank angle sensor

refitting of sensor is opposite of removal

hope this helps this is out of haynes commodore repair manual i havent done this myself but if u know any mechanics they should be able to help

[VQXTC]

Hey there dan, I found the problem. It was a wire which had come out of the cas plug. I had the black wire completely not touching it had somehow pulled out of the plug.......So I put a new plug on and that solved the problem it has never run so good......

Thanx again for all the help.....

cheers

simon

[dan_man31]

cant get any better then that same thing is happenin with my afm plug 2 wires are coming out i spent ages tryin to find out why it was happening on and off finaly checked the plug and felt so stupid lol good to hear though

Dan