VL idles OK, hunts above that.

[Outwest34au]

Hi team,
on behalf of the guy next door....
His wife stopped the VL 6cyl auto wagon to fuel it up, after that it started and idled fine, but hunts above idle. At full throttle (1200 rpm maybe) it sounds like its being cut off by a rev limiter. If you open the throttle and try to drive it, it pigroots and lumps.
I've just been over and checked the codes on the ECU, nothing shows up as strange there.
I also clamped off the fuel return line to see if it would boost fuel pressure, that also had no affect.

Weve got multimeter and a workshop manual, can someone here point us to a logical starting point please.

Thankyou.

[vnv8driver]

could be a mixture of things, without seeing it the list would start at-
fuel pump
airflow meter
pressure regulator

There the first ones to come to mind

[VL_5SPEED]

Sounds like AFM or CAS.

[VL Berlina 5speed]

from my understanding you need fuel air and spark to work
if it wont rev over 1200rpm you starving the engine of either fuel or air and causing a limp mode

turn ignition on and walk to the fuel flap area.
can you hear the fuel pump humming as it primes??
the pump should produce a humm or buzzing noise if its working even when the engines running.
if no sound then there fuel pump has died


i recall some thing about the catlic convertor collapsing which causes problems but im not sure if it would cause those exact probs, ill find out

check for spark. if there is no spark at all from the coil lead THEN it will be either the CAS or the coil. If you have spark then it will probably be the CAT (catalytic convertor). When the CAT is stuffed the mesh in side deteriorates and blocks the exhaust allowing the car to only go 20km/hr if you're lucky, even not go at all.

[Doctor Bob]

the air flow meter is faulty

[GoldCoastCommodoreSpares]

cat converters will usually stop a motor from running period in my experience with them, but i suppose anythings possible, restriction to the exhaust will prevent it from running/running properly. If that is the problem it wont last long until its stopped completely. remove and inspect it to make sure but by the sounds of things most likely a fuel/electrical issue

[BUT50]

maybe a vacuum leak?

[Outwest34au]

Thanks for the rapid responses guys,
tested fuel pressure and checked all vacuum lines for leaks again, and fuel regulator doesnt have fuel in vac lines,
Looks like a CAS at this stage, he did put a 2nd hand dizzy in a few months ago Ive found out.
Will let you know the outcome, cant get a CAS till monday here.

Thanks again.

[harry3]

if its the airflow meter, removing the plug from it will make no difference

[Doctor Bob]

Thanks for the rapid responses guys,
tested fuel pressure and checked all vacuum lines for leaks again, and fuel regulator doesnt have fuel in vac lines,
Looks like a CAS at this stage, he did put a 2nd hand dizzy in a few months ago Ive found out.
Will let you know the outcome, cant get a CAS till monday here.

Thanks again.

its the air flow meter, dont mess with the distributor

[Chirpstr]

I have a spare working one if you need.

[Holdfast]

Thanks for the rapid responses guys,
tested fuel pressure and checked all vacuum lines for leaks again, and fuel regulator doesnt have fuel in vac lines,
Looks like a CAS at this stage, he did put a 2nd hand dizzy in a few months ago Ive found out.
Will let you know the outcome, cant get a CAS till monday here.

Thanks again.

Mate don't forget that the second hand dizzy may have a stuffed bearing.

If the bearing is buggered it may put rust dust on the Crank Angle Sensor and the steel Rotor plate that has the slots cut in it.

You may not have to replace the CAS but maybe cleanup the CAS and rotor.

The bearing for the dizzy only costs about $7.

Best of luck

[Outwest34au]

Latest update...,
we put a new CAS and bearing in the dizzy, figured that wasn't going to be lost money after all the 2nd hand ones he has fitted. That never fixed the problem.
We borrowed an airbox lid and bingo, problem solved instantly.

So, I can go ebay-ing, but I thought I'd see if anyone here has a good 2nd hand or surplus new AFM they would like to convert to cash.

Thanks again for the help.

[maxpower QLD]

I had a similer problem with my AFM so i decided to test it (you'l need a multimeter to do this) before going out and buying a new one and found that the screw had been adjusted too high . To test and adjust mine i removed the ruber boot off the plug on the AFM turned ignition on and inserted one probe on number 6(the wires are numbered on the AFM) and the other on number 1 , then i adjusted the screw til the multimeter was reading 3.55 volts or 382 Ohms . Your AFM might be beyond repair or what ever but its worth a try . I did it to mine and i was amazed how much of an improvement it's made to the car lol it revs so smoothly and pulls harder through gears (now my CAS is about to pack it in) but as i said it prob won't make a difference to ur AFM but its worth a try and may save u $150 bucks or so . Anyways thats my 2c

[Outwest34au]

Thanks Maxpower, as a stopgap measure I thought I might adjust it while we waited for the new one, It read 402 Ohms. When it was adjusted to 382 made no difference what so ever.

Thanks for the help from all the interested forum members.

Chalk this one up as 'case closed'

Cheers :-)

[eko]

guys wats CAS ???

[Bax]

Was it the CAS (crank angle sensor eko) or the AFM?

I would have said CAS because the AFM only deals with the mixture under 1200 and then the cas takes over.