vacum on tb

[johnny27]

fitted a 1800 tb, where do the vacum pipes at the bottom of the tb go, the 3 beside each other on the bottom right hand side of tb?
At present i've just blocked them off, because there is no where for them to connect to on my 1.2, have attached vacum tube on back of manifold, and vacum at the side going up to a little unit on the bulk head (don't know what the little unit is), btw have'nt got a clue what they're for. So anyone any ideas what i should do with the 3 vacum outlets on the new cav 1800 throttle body? it could be what is causing my idle speed to be reving so high, or is it alright just to block them? Sorry for the long post and loads of questions, i have no idea of SPi units, i'm used to working with carbs. Cheers

[Adam]

WHere were they on the old 1.2 tb?
Do you know?
As the connections are the same

[johnny27]

the old 1.2 tb there is 1 vaucm pipe on the front, where as on the 1.8 there are 3 on the side

[Adam]

The one on the front goes to the airbox iirc.

[johnny27]

managed to switch the new 3 vacum pipe plate to my old 1 pipe vacum plate, so thats now sorted. Engine still idling high, thinking 1. air leak, 2 need 1.4 injector. What do you think? BTW the throttle plate is tottaly closed so how is the engine still getting fuel and reving high?
What is the little unit on top of the firewall, its got a plug and a vacum hose leaving it? Thanks for all your help
Also there is one other thing its called vacum control unit, its got 2 pipes in and 1 pipe out which is'nt connected anywhere, should this go somewhere on the spi?

[Adam]

The sensor on the firewall is the MAP sensor, it has vacuum pipes going to it.
If you've left one of the pipes off it will cause a air leak.

Not sure what your referring to with the vaccum control unit?

Have you fitted your old ICV into the new TB?
Or left the one that was already fitted in it?

Try your old ICV.

How high is it idling?

[johnny27]

where does the map sensor vacum line enter? is it back of manifold or where? there is a oulet on the rear of the manifold beside the water tube, does MAP tube go here?i have'nt changed the ICV, have'nt got a clue where to start, its idling around 3000rpm

[Stanley]

ive just got myself a cav 1.8 spi TB and a 1600 astra inlet manifold too

any tips to share?

i also have the astra 1600 TB too if thats any use

cheers

[johnny27]

do you know where the map vacum tube attaches to the manifold, is it the pipe at the back? will pm you with my experience later

[Adam]

Right.
MAP sensor goes to connection at the back of the tb.
The manifold has a small connection next to the coolant pipe, this goes down to the breather box thing(by the starter motor)

Front of the tb has 2 connections, small one is for the airbox.
The one on the left of the front goes to the carbon canister(it has like a clothy type pipe,lol)

Let me know if that sorts the idle, im planning on doing mine sometime next week.Lol

[johnny27]

Right.
MAP sensor goes to connection at the back of the tb.
The manifold has a small connection next to the coolant pipe, this goes down to the breather box thing(by the starter motor)

Front of the tb has 2 connections, small one is for the airbox.
The one on the left of the front goes to the carbon canister(it has like a clothy type pipe,lol)

Let me know if that sorts the idle, im planning on doing mine sometime next week.Lol

Hi mate, connected all like you said, still no better. Do you know of any website's that explain howto replace the icv? I don't know where it is located on the tb. Thank you very much for all your help, hopefully i could get it switched over tomorrow and let you know how it is running, i'm anxious to see how the engine preforme's with the englarged tb and 285 cam, suppose you would be too if your going to try the tb mod. Cheers

[Adam]

The icv is the black thing at the front of the tb as you look at it from the front of the car.
It has a plug on with 4 wires.
2 small torx bolts hold it.

[Adam]

ICV-Bottom left of tb
http://img.photobucket.com/albums/v86/Nova-crew/ICVontb.jpg

When you start the engine and its idling too high, is the ECU flashing on?
Or not.

[johnny27]

sometimes its on, then sometimes its not. i will go ahead and switch the ICV tomorrow. Thanks again

[Adam]

Any news on this?
Did you sort it?

[johnny27]

I changed the idle control valve and its still no different. I'm going to a scrappy at the weekend, i'll pick up another 1.8tb, 1.4 injector and possibly a manifold without the EGR. Will let you know if i get it fixed, its a real pain, considering i thought it would be striaght foward when i started. Thanks

[Adam]

Hmm, im really not sure why its idling high.
THe icv is allowing the right amount of air bypass the throttle plate, so it should idle fine.

Theres not really much than can go wrong with the TB, apart the the icv/tps etc, the rest is mechanical.
Try changing the throttle position sensor, its on the right hand side.
Just swap it for the one off your original throttle body.

When its idling high, is the ecu light on? Or not?

[johnny27]

ecu light is now off. Had to reset it on my obd2 machine, it just came up MAP sensor and Idle stepper motor, the faults cleared fine.

[Adam]

Still sounds like an air leak to me.
You dont need much air to make it run at 3K rpm.
Look how little the hole for the icv is.

So a small leak somewhere which cause it to idle high.

[Stanley]

ive got the 1.8TB and the 1.6 inlet and all this is starting to put me off lol

hmmm hope this works OK

[Aragorn]

right ive done this and wrote the guide so here goes:

the 1800 TB has a throttle stop screw on it which as it comes off the cav is set too high and will mean it will idle very high (over 2k iirc)

if u look closely at the linkage you'll see it comes down against a screwed rod, on the other end of this screwed rod all u can see is a metal blank, prize it out with sharp thing and u uncover a screw, wind this screw back untill u get sensible idle then get the engine FULLY warm, then continue winding it out until its idling at 900rpm

if u cant get it down that far u have an airleak somewhere, but if u wind the throttlebody down u should be able to hear the leak very clearly..

once the idle is correct you should be good to go, however note that it will idle high on coldstart as the ICV channels are much larger and the fine control isnt quite right

[Aragorn]

idle stepper fault is occuring becuase the ecu has closed the ICV completely and its still idling high so it assumes a fault with ICV

map sensor fault will occur if its not piped into manifold?

[Adam]

Also swap your ICV back to the 1.8 one.
The 1.2/1.4 has a different icv, the plunger is a different shape.
Which i didn't know till yesterday.

With the 1.2/1.4 icv you will get a high idle, as the plunger end doesn't fit the hole inside the tb correctly.

[johnny27]

will do that, as for the throttle stop screw, the flap at the bottom of the tb is fully closed on idle, will adjusting it be any good for as far as i see its already fully resting?

[Adam]

Hold the tb up to the light and you will see light around the throttle plate ;)
Closing the gap should lower the idle.