I have to say, no offence, I hate that term no effect whatsoever.
Should be writing no noticeable effect whatsoever instead.
Only way you are going to know no effect whatsoever is with flow and engine cell dyno testing with and without... Something ford have probably done already which is why they installed the flaps in first place because it solved something they perceived as a problem and nobody is qualified other than ford to conclusively say the engine is better off without them... Was designed with them, ford don't spend money designing, developing and testing things which are useless to an engine... It's too expensive... And makes engine more expensive to make also which doesn't fit in with fords money saving.
Yes people post that engine runs fine without them and anybody who wants to run without them also up to them... But nobody other than ford it's designers and testers are qualified to make the judgement that the engine is better without them.
Well said. I have waited til inspecting my flaps before commenting on this issue.
I agree things are put there for a reason. The flaps apparently assist low rpm air flow, aid spark, and do something for emissions and/or low end power.
I already noticed, with the vacuum hose to the flaps actuator disconnected, that the engine gives a worrying kick when applying power from idle. That's to say, from an idle-cruise, the engine jolts when the accelerator is touched. Feels a bit like a gear change. I have seen one other mention of this symptom on this forum. It's drivable but would annoy me and I wonder if it's doing harm. I assume this is something to do with the different air flow.
Then there are the other less obvious issues: fuel economy, are the plugs and leads being stressed (in which case avoiding the cost of replacing flaps might be a false economy), etc.
So, in my case, it turns out the flaps have been replaced at some point by the previous owner, and I estimate that they have done about 100,000 km. There is wear but I would say they're a ways from failure. Since the rod is re-usable, replacing the flaps at a cost of about 35 GBP is acceptable to maintain as-designed engine performance.
I will rotate the rod which will give me until-next-time life, at which point it will presumably be worn out. This is the most annoying part of this problem in my view, the 3.5 mm square steel being used is clearly far too soft. I had a brief look at stainless stock online but the closest I can find is 4 mm square bar, and then it's still just 304 or 316 which again will be too soft. With more effort it may be possible to find some harder duplex grade in the right size, that's a project for next time.
Now if the entire manifold needed replacing, because of the need for a new rod or other damage, the cost might make it a silly proposition on a 15 yr old Mondy, vis-a-vis going flapless and accepting the out-of-design air flow, so Paul definitely has a point there.