Air/fuel mixture screw that does nothing

[lyod]

Hi, the engine in my car did nothing when i adjusted the air/fuel mixture screw on the carb, now i am only able to adjust the idle through the air-con idle screw, is it ok to leave the screw or it is something i should be concerned about?

Topic

[Its me]

What year, make and model of vehicle are you working on?

[lyod]

Hi, its a 97 daihatsu mira

[Its me]

It should be a computer controlled carb…

As such, most carbs are sealed so that people (the most common problem) do not mess with them (think 3 mile Island, think Air France flight 447)….

99.9% of the time, the problem is not in the idle screws… It is somewhere else…

What you can do to fix the problem is find out how the screws “should” be adjusted from a dealer or professional… Most likely now they will have to be screwed in all the way and backed out a certain amount of times…

Hence if anyone is ever so inclined to make carb adjustments, they should always back them in and count them… remember the number of turns, and then remember them and adjust off that…

I have fixed many problems when people have tried to fix their own carbs by just messing with the screws… 99% of the time it was not the problem and I appreciated their honesty when they told me they F#@#!ed with the screws…. At least I knew I had to fix that too.

I always asked them “do you know what adjusting that screw does?”….. The answer was always the same… a stunned dumb look on their face with no reply….

Tell us about the base problem before you made carburetor adjustments…

-Karl

[lyod]

Thank you for your help, i went to a mechanic just now, apparently the previous guy connected two vacuum hose wrongly when they put back my engine after a transmission swap, a simple vacuum hose swap solved the problem, my brake also improved, thanks a bunch for your help

chong

[Author]

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