Why would your car run badly for the first few minutes?

warm up

A bad idle is caused by a problem with fuel or spark these are two different systems, both with multiple components. Let�s look at Spark first.

When was the last time the ignition components were serviced? I don�t think tat you need an electrical service (commonly referred t as a tune up) the idle would be consistently poor.

So let�s look at the Fuel side of the equation.

There are a few things that can affect the air fuel ratio like carbon, and varnish.

I would try to clean a few things up before wasting money on a fuel pressure regulator and especially on an idle air control valve. I recommend that you First check a plug to see its condition (only one if one is bad well you can figure the rest out) if the plug looks good move on:

1) Injection clean 2) throttle body and induction system clean 3) Carbon chemical clean

More likely than not you have a carbon build up problem this causes a fuel soak condition that causes a hard start and a rough idle until the fuel burns off. Of course someone may tell you that you have a burnt valve but again this would cause a consistently poor running engine.

Answer

It sounds like fuel related. Depending on the year it could be a choke or the cold start sel. Does it smoke? What color smoke? Black would indicate rich mixture of fuel. Or it can be running to lean until it warms up.

First answer by april chandler. Last edit by Ganderton. Contributor trust: 1754 [recommend contributor]. Question popularity: 184 [recommend question]