Im not sure if this is in the right folder, but anyway…
I’ve been thinking of giving my throttle body a good clean, mainly because when I take my foot off the gas the revs (occasionally) drop to ~550rpm, before recovering. My 5 is a '91 with 88k on the clock, and I doubt it has ever been done. If anyone has any other suggestions that might help this then I’m all ears.
But anyway, the point of this post is to ask where (in the UK at least) I can get throttle body cleaner? My local car parts shop and halfords could only offer me carb cleaner or brake cleaner - which I’ve read should not be used due to the protective film on the valve.
The only place I’ve found that says suitable for use with coated valves is in the states, which seems a bit extreme to me.
I’ve used Wynn’s Intake Cleaner (Halfords), which is xylene based. Benzene-based cleaners can strip the anti-sludge paint. Benzene is generally considered a fairly bad chemical theser days (carcinogen http://www.epa.gov/ncea/pdfs/benzenef.pdf), so I expect most “carb cleaners” these days are benzene free.
I’d be wary about going too ballistic on the throttle body itself. Ford applies a “pre-sludge” coating, at least in the US, to minimise fluctuations in idle speed on new cars. Some reference here:
Even if a solvent doesn’t lift the paint, mechanical rubbing of the butterfly might be enough to damage the seal. The paint applied is done in an incredibly crude fashion. Some say that Ford didn’t intend their paint to be long lasting, based on the assumption that a build up of crud will naturally provide a seal. I know of an owner who successfully reapplied a coating using thinned down Humbrol paint.
But, I know of no coating in the ISC valve, under the throttle body, which is basically a stepper motor. That can gum up, and could be worth cleaning. But, you will need a fresh set of paper and rubber gaskets from Mazda.
The other source of idle dips are leaks in the intake; worth going around and checking all the connections are sound, if necessary, cleaning them up a bit (I’m not sure if anyone has considered how a piece of plastic trunking might wear after 20+ years). Idle control is supposed to have been one of the biggest technical challenges wehn eletronic fuel injection was introduced, so one could imagine its a fairly finely balenced system.
I’ve also found a low battery to cause this problem on mine. The base idle may also need resetting and this would be worth doing if you find the throttle body to be really slodged up (details on this are probably on this forum somewhere, but can be found in the Rod Grainger Enthusiasts manual).