This copy’s seen better days! I’m sure I have one in better condition somewhere….
Interesting that the air injection diagram is really only indicative on how the system operates. The actual channel bw the heads is through the centre of the inlet manifold & more often than not would be completely blocked by carbon within a few years of operation. Once the airpump seizes from a lack of decent lubrication & other valve failures, the channels in the heads would quickly block up & the only way to correct the issue is head removal. If you add the EGR system to the mix, the engine will slowly choke itself. I often wondered why people were so against the emission gear since it was designed to cut out at full throttle anyway. Perhaps others weren’t aware of this fact? Certainly the EGR pipe under the too-small-for-the-engine throttle plate affects air flow. Now I’ve come to realise the system has numerous points of failure & carbon deposits are a very real issue. Carbon deposits on every intake surface significantly affects performance. This carbon layer would become thicker every time you turn the key and worse still on short drives with long periods on a closed throttle.
It’s likely the designers never really considered the longevity of the system. It was designed to clean emissions, however in the real world it just makes the inside of the engine filthy and robs it of the power it once had when it rolled out of the showroom.
