For anyone interested I installed an aftermarket Throttle body and Plenum to my 2003 GT. Added an Accufab Plenum and 70mm throttle body. Went 70mm from reading and asking but the size and make is entirely dependant on the car/mods and owners requirements.
Took me about one and a half hours as I`m no mechanic and wanted to double check everything and make sure I done everything right.
Slow test drive then a the same run as earlier. I`ve never been a fan of `bolt on` stuff on any N/A cars as they offer very little for the cash in terms of anything really. The Diablosport Predator 93 tune offered and I noticed virtually nothing although it did make the auto box shift better, the
K&N made no difference, the cat backs made just noise but...........I knew that before spending the money. When added up they all will, however make a difference to the output of your motor.
Anyway, not a full pictorial installation guide nor a bonefide guide. If theres any inaccuracies please let me know and I`ll edit it accordingly so it is more helpful to others. Its pretty straight forward and not as difficult as you might think.
First, Disconnect the Battery
In no particular order I began dismantling the components off the stock plenum starting with the Idle Air Control valve. The 3 main parts are EGR valve, TPS and IAC valve.
In the above pic I`m pointing out the 2 main bolts holding on the IAC valve. As you can see I`ve already unplugged the `elbow` joint and hose from the plenum. A new gasket should come with your new plenum for the IAC valve.
Next I removed the Throttle Position sensor (which I`m pointing out). The two screws holding it on have been locktited from the factory so use the correct screwdriver as you
can`t afford to round off the screws. Use a lot of pressure on the screws and slowly turn to loosen them off. You might hear a slight crack then you`re good. I also disconnected the relevant electrical plugs and connectors. You can easily see what needs unplugged.
EGR valve is a simple 2 bolt affair and using a long 10mm socket made life easier. Theres also a gasket supplied for this. If theres not and the gasket looks like new , as mine did I can see no reason why not to reuse it. However new is preferred.
After carefully removing all the bolt ons, including all the pipework to the TB and the red electrical plug. Theres also a small air pipe to the back of the plenum under the throttle linkage. I`m pointing out one of 5 plenum bolts. All are easy to access.
After the 3 main things are off there are a couple of smaller also important bits to disconnect. At the back is the throttle set up which is attached to the plenum with two bolts on a small bracket. The cruise control is the small black connector which just clips on and off. The throttle cable itself is just like a bicycle brake cable and threads round the black cam roller. The spring just unhooks. Turn the throttle to WOT to make things easier. ie; to give yourself more slack.
When you`re all stripped down your engine should look like this. Do a nut and bolt count (they should be kept well away) and make sure NOTHING falls down the hatch :-s. Your new Plenum kit will come with replacement bolts/screws dependant on manufacturer.
If you have a pre 99 GT you might have a smaller pipe than the one in the picture. Accufab supply an adapter but other makes (
BBK, dragon ect) maybe won`t I`m not sure. Don`t adjust anything on the thing as they come pre set.
End result.
Fitting is a complete full reversal of removal. Don`t rush and check everything is secure. DO NOT over tighten the new Plenum with the 5 bolts as the upper intake manifold is plastic and we don`t want any problems in this area.
Findings?
I had taken the car out a good run prior and when I was all done, started the car up to check there was no leaks and it idled fine. Just a slow run round the block then back to check for any leaks or any possible mishaps. Then took it out on the same run I did prior to install.
I can honestly say, hand on heart that the car now has a much improved throttle response. Before there was that `lag` before it pulled, like a delay of some sort for want of better words. All the stock (ish)modular SN95 4.6s seem to have that notorious lack of `low end urgency` when compared to the 5.0. BUT, they more than make up for it higher up the rev range. Bottom line is, its a noticeable difference in the way the car feels and pulls from a dig, so its a result.