A_Volvo_Driver
I put this one in the Technical section as I think that this may help other people.
I am seeking advice on the best way to proceed. I have removed the snorkel hose that leads to the top of the air box (it had an air leak) and blocked off the hoses at the engine end with wheel nuts (adds some much needed bling LOL). The metal pre-heater tube that lead from the manifold to the bottom of the air box was disconnected at both ends, so I removed it also.
This was done a couple of months ago. I have noticed that the car runs a bit lumpier when cold, but is fine when the car warms up a bit. I am assuming that the current setup is not ideal, is there anything that can be done to the air box to make it run better than factory, or should I look to replace the top snorkel hose?
Angus242164
This is a B23E engine I take it? I doubt the changes to the emissions systems you've mentioned will cause it to run rough when cold, I'd say you might have a vacuum leak (split hose somewhere, leaking injector seals etc.) or perhaps a dirty throttle body or gunked up idle control valve.
The pre-heat tube is connected to a thermostat in the bottom of the airbox, and when the ambient temp is low enough, it moves a flap so that the air entering the engine comes from the shroud around the exhaust, rather than from behind the grille area. The idea is to warm up the engine faster, as cold engines use more fuel and produce more emissions.
I'm pretty sure that in the Australian climate, it never gets cold enough for the thermostat to switch the flap over to the exhaust side, unless you live at a ski resort, so removing the hose won't affect anything.
The other hose that you've disconnected and plugged is part of the pulse-air emissions system. It uses pipes and a hose to connect the exhaust ports in the head to the airbox, via a pair of one way valves on the side of the head. It allows pulses of fresh air to be drawn into the exhaust, to help combust unburnt fuel in the exhaust, reducing visible particulate emissions.
Disabling it shouldn't affect how the car runs, especially at idle, but it's generally advisable to remove the pipes and valves as well, and plug the ports in the head that the pipes connect to.
