Whenever i first start my '95 4runner, after its sat over night, it will shake and sputter like its running on 5 cylinders, which im pretty sure its doing. Then after about a minute or two the rpms will go up and it will run fine. Only when its been sitting for a while, like overnight. All the plugs have been recently changed, but one is a stock NGK and the rest are Bosh dual electrode. The NGK is there because its stripped and stuck in the cylinder head, but its only about 6 months old.

Could this be plug wires? The ecu is also throwing a code for the knock sensor, but i think its because its sitting in between two vacuum lines and cant hear anything. thanks

 

anyone?

 

Hi,

When it is running poorly pull off one plug wire and see if the idle changes, if not go to the next one. I'd start at the NGK plug to rule that one out first.

Is your cold start valve plugged in? Maybe you aren't getting the fuel enrichment?

Take off your throttle body and clean it till it shines, pay attention to all the little vacuum holes AND the Aux Air Bypass valve which is operated by the coolant lines passing through. If that is gummed up and sticky it could produce the symptoms you describe.

There is no other time it runs poorly? A rain storm or amazingly humid day? Thinking leaking wires or moisture in the cap that gets dried out as the engine warms up.

ECU temp sensor on the back of the intake not working?

How did it run before the new plugs were put in? Were they put in to fix the poor starting?

To help you it often helps to know what area you live in, dry desert, wet pacific NW, Frozen Plains States, etc. Some problems are climate specific.

Hard to say without seeing the truck, one can only do so much with a keyboard!
I do strongly suspect the cold start system though. That is the fuel valve, the temp sensors of both the water and the air and of course the air valve.

Dave