Exhaust Air Pulse System removal

Guide by Gavin Dent

The exhaust manifold on the rs2000 16v escorts is well known for being restrictive. The reasons for this are partly to do with the construction method of it and also due to the air pulse System (APS).  This system is also incorrectly known as the EGR (exhaust gas recycling) system, which it is not, that is a completely different type of system.

The APS's job is solely to speed up the heating of the Catalyst in order for it to work efficiently, that's all.

This system is only used on the warm up cycle and it does not affect the emissions come MOT time as this reading should be done when the car is at working temperature. Due to this fact many rs2k owners remove this system. First you need to remove the manifold.

We will start with the APS and below is a diagram and a list of parts:

1)      Manifold 2)      Pulse air tubes 3)      Pulse air valves 4)      Air control system 5)      Pulse air filter 6)      Lambda/hego sensors x2.

 This mod will remove parts 2, 3, 4, 5 and all relevant pipe work.

 Jack up the car and support on axle stands. Remove the starter motor and radiator fan to give you some room to move in and also remove the dipstick tube. Unbolt the APS pipe work from the top of the manifold and remove it. Unbolt and support the exhaust system from the down pipe back. Undo and remove the two lambda probes from the down pipes, taking note which one went where. Be careful with these, as they are fragile. Unbolt the manifold from the head and remove the manifold from the car.

 Inside each branch you’ll see a pipe as shown below that it what is going to be removed and how you do it is up to you.

You will be left with 4 rather large scary looking holes in the top of each branch in you manifold, now you need to find a good welder!! Get these holes welded up and while you are at it get the branches welded to the mounting plate around the outside.

This brings us to the second part of the restriction in the construction of the manifold.

If you take a look inside the branches of the manifold, you will see a weld running round the inside.

The original welding leaves a large blockage in the port of the branch.

 What you want to do is grind off the weld on the inside (the reason for having it welded on the outside) so it looks like this:

As you can see there is a vast improvement in the size of the outlet.

 This is a one way mod, as re-instating the APS tubes is not going to be easy.  As such it’s worth removing the small mounting bracket for the APS valves that’s located on no.4 branch.

 Although these mods will not give you a big hike in power or be noticeable (at best 1-3bhp) they will enable other mods to work better and when combined with a de-cat pipe a good quality free flow exhaust and an air filter, you will get a good improvement in pick up and mid range torque and, considering it is almost free it would be rude not to do it really wouldn’t it!!!

 Another mod that can be carried out whilst the manifold is off the car, is to wrap it in heat protecting tape/cloth.  This will help to keep the under bonnet temperature down and can help power to a small degree by keeping the exhaust gasses that bit hotter, therefore they retain a bit more energy and thus velocity.  Plus it also looks good.

Oninonfx’s car and heat wrapped manifold.

(Note non removal of APS pipes and mounting bracket.)

 Aftermarket tubular replacement manifolds are available for our cars and are usually in stainless steel.  They may be a bit better flowing then the standard Ford item and are also lighter, but they can cost over £300.