2lt Mi16 Engine Problem

[pug309twin40s 1]

right im having little problem with the acav system on my 405.

 

the problem is the diaphrams are opening the butteflies in the inlet manifold all the time instead of just opening then from 2500rpm till 5500prm where they should or around them revs,

 

which means the engine is getting too much air at low and high revs so is bit flat and crap at high revs.

 

ive fitted a new cylinder on the end of the cylinder head the connects to the diaphrams and its made no difference. which way is the hoses supposed to connect if it makes any difference?

 

if i connect 1 way the vavles open all the time if i swap the hoses round then the butterflies are closed at idle but open when throttle is open/applied.

 

 

what does the big round cylinder do that the hose from the little cylinder connects to do? could this be the problem?

[pugrallye 0]

its a vacuum reservoir, and the valves should be shut below 1800 rpm and open above that

Edited September 5, 2006 by pugrallye

[pug309twin40s 1]

its a vacuum reservoir, and the valves should be shut below 1800 rpm and open above that

 

 

ok cheers.

 

well mine open all the time. so what actually controls the vacuum to open the vavles?

[pugrallye 0]

solenoid on the side of the head (two pin electrical connector attatched) lives just above the vacuum reservoir

[pug309twin40s 1]

solenoid on the side of the head (two pin electrical connector attatched) lives just above the vacuum reservoir

 

 

ive just replaced this with brand new from pug. and it made no difference. electrical connection on it with 2 hoses connect at the front and a connection out the other end that doesnt connect to anything?

[pugrallye 0]

yeah thats correct, is the solenoid actuating though? pull diaphragm feed pipe off and test for vaccum whilst you hold rpm at about 3000

[pug309twin40s 1]

yeah thats correct, is the solenoid actuating though? pull diaphragm feed pipe off and test for vaccum whilst you hold rpm at about 3000

 

 

it must be working cause the butterflies are closed at idle but as soon as you open the throttle the diaphrams operate and open the valves.

 

 

 

but i'll go and do some more testing.

[Guest jim01uk]

IIRC the butterflys move at 1800 at 5000RPM and change the inlet characteristics - they do on my S16 anyway!

 

At engine speeds below 1800 rpm and

above 5080 rpm, the ECU closes the solenoid

valve, shutting off the vacuum supply to the

diaphragms, and the butterfly valves are

closed. With the valves closed, the short inlet

tracts are closed, and the incoming air flows

only through the long inlet tract, boosting the

torque output.

5 At engine speeds between 1800 rpm and

5080 rpm, the ECU opens the solenoid valve.

The vacuum present in the pump is then

allowed to act on the vacuum diaphragms,

which draws the pushrods into the diaphragm

bodies, and opens up the four butterfly valves.

With the valves open, the incoming air is

allowed to flow through both the short and

long inlet tracts, for maximum power

 

and i think the vacuum valve is controlled by the ECU.

Edited September 11, 2006 by jim01uk

[pug309twin40s 1]

IIRC the butterflys move at 1800 at 5000RPM and change the inlet characteristics - they do on my S16 anyway!

 

At engine speeds below 1800 rpm and

above 5080 rpm, the ECU closes the solenoid

valve, shutting off the vacuum supply to the

diaphragms, and the butterfly valves are

closed. With the valves closed, the short inlet

tracts are closed, and the incoming air flows

only through the long inlet tract, boosting the

torque output.

5 At engine speeds between 1800 rpm and

5080 rpm, the ECU opens the solenoid valve.

The vacuum present in the pump is then

allowed to act on the vacuum diaphragms,

which draws the pushrods into the diaphragm

bodies, and opens up the four butterfly valves.

With the valves open, the incoming air is

allowed to flow through both the short and

long inlet tracts, for maximum power

 

and i think the vacuum valve is controlled by the ECU.

 

 

 

cheers for that jim. hmm could the ecu be at fault then if the butterflies are opened all the time?

[Guest jim01uk]

check that the cams which the diaphragms are connected to havent siezed as this has been known to happen too.

[pug309twin40s 1]

check that the cams which the diaphragms are connected to havent siezed as this has been known to happen too.

do you mean the bits that the arm that comes out the diaphrams connect to?

 

if so then there fine as i can get the diaphrams to be closed at idle .but as soon as any throttle is applied the diaphrams open and open the butterflies and i can manually operate the arm etc. everything moves.

 

 

does it matter which way the hoses on the little cylinder on end of the cylinder head connect?

[pugrallye 0]

prob more likely you have solenoid plumbed in incorrectly as they sound like they are immediately recieving manifold vacuum (but you siad they opened at trigger RPM???)

[pug309twin40s 1]

prob more likely you have solenoid plumbed in incorrectly as they sound like they are immediately recieving manifold vacuum (but you siad they opened at trigger RPM???)

 

 

how should the hoses connect to the soleniod? i'll have a look to see what one goes where? should the hose from the reservior big cylinder go to the connection pointing out forward from the soleniod and the hose to the diaphrams come from the connection pointing upwards on the soleniod or the other way round if it makes any difference.

[Guest jim01uk]

do you mean the bits that the arm that comes out the diaphrams connect to?

 

if so then there fine as i can get the diaphrams to be closed at idle .but as soon as any throttle is applied the diaphrams open and open the butterflies and i can manually operate the arm etc. everything moves.

does it matter which way the hoses on the little cylinder on end of the cylinder head connect?

 

yeh the bit that the arm connects to.

 

Im not sure what the problem is - from that description they are working as they should. i think that the 1800rpm opening is a little high, and more like 1080rpm. all you have to do is apply slight pressure to mine to raise the revs slightly and the valves open. carry on raising the revs and the arms move again to close the butterflies.

 

how does it drive? if there was a fault, it would feel really flat (and i mean REALLY) below 5000RPM - is there a huge change of characterisitic in the power delivery? there is always a slight change that is noticeable, but a blatt through the rev range should be fairly smooth. If its not working, the change at 5000RPM feels like a turbo coming on boost. slow slow slow slow goooooooooooooooooo!

 

I'll get under the bonnet of mine tonight and see how the control valve is plumbed in!

Edited September 12, 2006 by jim01uk

[pug309twin40s 1]

the car doesnt fell that powerfull. doesnt really pull at low revs only pulls between 3000rpm to 5000rpm above 5500rpm it just goes flat.

 

if you pull the hoses of the diaphrams so their not operating so butterflies are closed then the car is flat as hell below 6000rpm but then at 5.5k to 6k it takes of like a scalded car lol.

 

 

 

my old 405 2lt mi16 that welshpug now owns the butterflies didnt open until about 1500rpm then shut about 5k and that pulled hard and was fast.

 

where this with the system connected just doesnt seem fast and is annoying.

 

i'll try and get out a take a video of how the butterflies are working etc at the moment.

[pug309twin40s 1]

right made a little video of the car this morning while out:

 

http://homepage.ntlworld.com/pug309twin40s/Video000.3gp

 

will have a good look at the acav stuff on thursday when im not working.