TD5 Exhaust

[nedflanders]

Hi, just fitted a full system to my TD5 90 and thought I'd share a few first impressions. Now I know someone will start jumping up and down about the legal implications but before you do, please, just don't.
System is a downpipe minus cat, centre box removal pipe and standard rear silence.
First impressions- A slight increase in noise under acceleration (just a touch more throaty rather than V8 Commodore attract the police noise) but cruising speeds seem quieter.
Definitely more pull in the mid range, most noticeable in 4th, less gear changing needed when slowing down for junctions as it'll accelerate easily in 3rd where as before it needed a change to 2nd.
Engine temp has dropped by a couple of degrees, used to sit at 83-85, now more like 80-83.
Fuel economy is yet to be calculated so will let you know but from what I've heard about cat removal it can only improve as long as I keep driving as I did, it's very tempting to keep seeing how well she goes now :D

[mools]

Year that exhaust mod will make a nice improvement to the drivability without a doubt. I like the noise on tickover too, its just pleasent.

Just wondering, have you done the air box mod? And have you tried disconecting the clutch switch? If not I'd recommend both. Whilst the improvements are only incremental they help with the transformation of the vehicle. Especially the clutch switch, after all if you don't like it, just plug it back in. I'd not bother to modify the air box if I wasn't running a snorkel though.

Ian.

[nedflanders]

I haven't done the airbox mod yet, what are the gains? also what would disconnecting the clutch switch do? I've fitted cruise control so I'm guessing that would mean it won't disengage by pressing the clutch pedal?

[mools]

Yes, if you unclip the clutch switch you can't use the cruise, it wont engage at all (well the way I wired mine in it won't). BTW dipping the clutch is a savage way to knock it out of cruise.

It's difficult to say exactly what it does but it's there to stop the transmission getting shock loaded during/after a gear change, it subdues the engine revs. To stop over revving when the clutch is depressed. Basically, and to quote someone else, if you can drive you don't need it. Just disconnect it and go for a drive, you'll see. No more lazy take off, shifting 1st to 2nd is less of a chore, better pick up after a gear change. The vehicle becomes a lot more drivable - especially off road. Give it a try. Unless I'm going on a long journey, when I want the cruise, I just leave it unplugged.

The air box is one of those little things, you most probably will not really notice a dramatic change, but incrementally these things all add up.

Try it, I bet you won't regret it.

Ian.

[nedflanders]

Cheers Mools, agree I never disconnect the cruise with the clutch, just a dab on the brake pedal to get the lights on.

From what I can gather the fuel is cut during gear changes, the clutch switch is normally closed, allowing current through until the pedal is pressed and then it's cut (the voltage measured at the plug is 12v and the switch cuts this when it is pressed). So I think for the Cruise to work the ECU has to see 12v from the switch and as soon as the pedal is pressed and cuts the 12v the ECU disengages the cruise. So I'm thinking if I join the terminals together at the switch plug the ECU will still see 12v from the plug but won't realise when the clutch is pressed and won't cut the fuel hopefully meaning I get the driveability and cruise will still work or am I talking bollox!!
Anyone have any ideas if this will work?

[mools]

Mate, let me know if your plan works, I had though about sitting down and thinking about it, getting the multimeter out, wireing the plug across itself and seeing if i could have the best of both worlds but just, well, never got to doing it.

But before that, have you disconnected it and gone for a drive? If so what did you reckon? Did you like it?

Ian.

[nedflanders]

Yes did the disconnect and could tell the difference, I plugged it back in and there's a definite sluggishness in 2nd, going to have a look with the multimeter tomorrow at work to confirm the switch isn't anything special and just cuts feed when the pedal is pressed, if it does I might stick a 5amp mini blade fuse in the plug and see how it drives.
What are the benefits of the airbox mod though, seems a lot of different opinions on whether its worth it?

[mools]

Glad you tried it and glad it worked.

RE the air box. I think the benefit is minimal but as I said incremental. Making it flow a little more freely has to be a good thing. Take the air box out, have a proper gander at it and I reckon you'll want to change it up. It's a bit of a marvel really, engineered to give every chance of separating water from air yet, just past all that, a small, maybe 6 square mm, hole in the bottom of the air box next to the ducks bill! Go figure!

If I didn't have a snorkel I wouldn't have changed it, but I do and once I saw what was in there it had to go. Anyway, pulling the air box takes a few mins, take the pipe connected to it and joined below the clutch box off too, if anything like mine there'll bit a surprising amount of **** in there, give it a clean have a look and make up your mind as to weather or not its worth it. If not seal up the little square hole and pop it back on, nice and clean. Bet you chop it up once you see it though.

My TD5 was set up well when I got it and it went like stink then, but I've done a lot of little things since, now it's so much, much more responsive. So much so that I have a boost box and MAF upgrade on the shelf but am in two minds as weather to bother with them (and the VNT that I don't have) as I don't want to try for too much and stress the engine an I think the performance is sweet as right now.

Let me know how you go with the switch,

Cheers,

Ian.

[nedflanders]

Tried bridging the plug with a 3amp fuse, cruise worked, ran but lots of flat spots and really held onto the revs between changes. Not sure why it ran worse as the switch has no resistance through it, very strange so back to running with the plug on, might put a switch in line in the cab to disconnect the feed when I don't want cruise :)

[Blade74]

So does this mean on my 2003 TD5 i have to remove the wire clip on the clutch master cylinder and put a shorting wire between the terminals of the wiring connector to disable the clutch switch?

[mools]

No, just unplug it that will disable it.

[Blade74]

Cool.
Thanks Ill give that a try...
Ill have to read up on this airbox mod a bit more too.