Engine Performance problem
1986 BMW 535 6 cyl Two Wheel Drive Manual 198000 miles
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Why do most cars have fast cold idle and a select few don't? Do non-fast idle cars have to run extra rich during warm up? Why don't more cars have the slow cold idle?

Hi there,

This is just at the whim of the designer i feel, some cars just use a cold start injector which makes it richer (like an old choke system, others use a idle air by pass system which is more complex and costs more, some of the systems are a nightmare to get right (early Nissan) while Toyota (cold start injector) is a dram and realy give a problem. I don.t know why there are so many different systems about, but i know one thing, each company will say theirs is the best.

mark (mhpautos)