Where does the VN measure airflow?

[VNCalais98K]

I had a problem the other day where my car just died in traffic and wouldnt start again... it was turning over but not catching.
Blowing a bit of black smoke, it was certainly dumping fuel like no tomorrow.

I pushed to the side and checked under the hood and the only thing i found (apart from my spanner set that i left on the strut tower... lucky it was still there) was that the join between the main intake pipe and the elbow that goes to the airbox had come apart.

Now in my old car, the AFM was there which meant that those symptoms would be caused by the car calculating zero airflow and not providing enough fuel.
In the VN, theres no wires or sensors that i know of past the TB, so I'm just wondering how the VN measures airflow that it would have had this result.

As soon as I reconnected this pipe the car ran like a dream again.

[hakhawk]

im pretty sure it doesnt measure airflow, but it measures air pressure and works stuff out from that.

the sensor is a map sensor and is screwed to the firewall on the passenger side and uses a hose that connects to the throttlebody elbow i think.

[VNCalais98K]

Well in that case, why did my car refuse to run when the intake pipe had come apart like that then?

[greenfoam]

Because your crank angle sensor is stuffed?

[immortality]

Because your crank angle sensor is stuffed?

WHOAH there is that CAS again

[VNCalais98K]

But i dont see the problem between:

1) intake pipe connected to airbox - runs fine

2) intake pipe to no airbox - doesnt run

3) reconnect intake pipe - runs fine.

If it was the CAS, wouldnt it be screwed all the time?

[hakhawk]

the CAS ca be random too. maybe go out to your car, rip that intake pipe off and see if it runs shit again

[greenfoam]

WHOAH there is that CAS again

Its that time of year again man:P anytime you get temps near 40c the dodgy CAS's start falling apart

[immortality]

Its that time of year again man:P anytime you get temps near 40c the dodgy CAS's start falling apart

doesn't get nearly that hot overhere so i guess we don't see that as often then. we just get the 99% humidity which sometimes i think is worse, hot & sticky

[VNCalais98K]

the funny thing is friday was cool and it had troubles for that 1 time. Saturday it was 41 and car ran sweet. with A/C on temp doesnt get above 1/4

[immortality]

the easiest way to check then would be to run your car and when it's up to temp pull the intake of the TB and see what happens. should run fine though. i'd go with foam on this and say it's more likely the CAS

[VNCalais98K]

Bugger.

Looks like ill have to pull out a gregorys.

On the bright side, Ive had my crank pulley off once this year already, so doing it again shouldnt be as hard as 18yr old loctite.

[VNCalais98K]

well, its confirmed.
This morning I went to move the car, and it started like shit, running on about 4cyls i reckon.
after 30 seconds or so, it levelled out to a smooth idle, but if you stab the gas, the car stalls.

Reckoning might have been spot on with that CAS thing.
I dont have time to change it over Xmas, how likely is this to be intermittent, or happen non stop?
Also, if I take it to a mecchy, what are they likely to charge to replace the CAS?

[padrickz88]

one little thing ive noticed is when posters like greenfoam or immortality (people who have alot of post, have been here for a while, and know what there talking about) say its something, then usually it is

[VNCalais98K]

Hehe... well, Im always a skeptic with everything in life... and i dont like paying for things to be fixed unless I know that its most likely the problem.

Like paying a grand for a timing chain to be swapped only to find there was nothing worng with the original, and everyone who said it was the chain, black and blue, was wrong.

Anyway... this is cheap luckily... $41 for the CAS and $70 for the changeover.

[greenfoam]

Well if its going to drop two cylinders like that you might want to investigate the coils too, which will drop two cylinders at a time (there is one coil for each two cylinders). The CAS should just kill the spark alltogether but replace the CAS anyway since it's allways good to have a newish one in the car, the local mechanic here does them here whenever a fuel pump fails or coils or whatever just so nothing will break again soon apart from that it's really only the DFI module that can do dodgy things with your spark

[v6vn/vpwagon]

I ahd the exact same problem a while ago. Didn't touch the cat but changed relays and it seemd to go away. Try that first (its alot cheaper)

[VNCalais98K]

Well the CAS was fairly cheap and quick to change, and car runs smoother (seems to) although maybe thats just me.
Also made the rattle noise a lot quieter.
It shouldnt conk out again.
But if it runs crap again, youre right, that isnt a symptom of CAS, and ill probably look at the coils, and also the fuel pump/filter.
At least i shouldnt have to remove the harmonic balancer for the next 100,000km or so... the chain and cas have been done now.

[goose2]

when you decide to change over the coils make sure you go for the vr ones they go straight on we sell them as a pack with dfi mine wnt 6 months ago with symptoms like yours 20 mins later [dropped one of those litle nuts] ran fine with new leads ,commodores like new leads and leads dont like to be touchy feelie ,lifted the bonnet one night looked like chistmas in july