16SE running problems - won't rev

[Iain]

I have a 16SE fitted to a Nova with a flap type AFM

It'll crank OK, start and tick over, but the moment you try and rev it it'll die immediately. The AFM flap doesn't seem to move when you rev it.

If I wedge the AFM flap open it'll rev though

I forget how this system works, what opens the flap? Is the AFM knackered or could this be caused by a big airleak after the AFM causing it not to open?

[dgbnova#1]

It could be air leak, serpristine alloy wheelsvo fail or servo pipe if its not easy to spot it just give that a good check all around

[Iain]

Well the intake pipe is ruined and now heavily gaffa taped up

It seemed weird that the flap didn't want to open at all, and for the life of me I can't remember how it works lol

[dgbnova#1]

It's electric iirc so should not open unless engine tells it to .

Find a replacement silicon one for the pipe is ure best bet as used ones just gona do same again

[Iain]

You saw the bit where the flap isn't moving at all so it chokes itself of air? Sounds like the AFM may be knackered then.

Don't really want to spend any major money as trying to get it up and running on the cheap so I know if it's a decent engine or not.

[mowgli]

i have a genuine gm diagnostic box for this engine i can lend you... i've probably got another afm too hidden somewhere..

[Adam]

Wont be an air leak else it would be revving higher than normal on idle. Surely this flap thing must have to open for it to rev?

[mowgli]

if the leak hasn't been picked up on, people turn the idle down on the ecu(afm), this causes it then to run terribly, but idle fine.. its a similar problem if the ICV or the CTS are fubared

[Will F]

That flap won't open unless engine is under load iirc.

could be loads of things... Fuel supply ok? Will it idle ok for a while? Ie is the engine just running on the fuel supplied when the pump primes?

[Jeff16v]

Fuel pump pressure drop on mine caused it to cut under load but run fine on idle, I had a small hole in the petrol supply hose. Any damp patches on the fuel lines?

[Iain]

Thanks all. Spare AFM might be useful Mowgli just to reassure myself, I'd have thought the flap opened even when stationary.

One thing I forgot to say was previous owner thought removing the intake pipe with AFM attached from the inlet helped it run.

I had to chuck some fuel in to get it to run this well, so I guess there could be a leak or something causing the pressure to drop. It'll sit there ticking over for 30 seconds without revving though, and when I ram the AFM open it'll happily rev right up and not cough and splutter, so I assume it's got enough fuel and it's purely air intake issues?