I turn it on it shakes?

PIPPE74

MEMBER
1999 FORD WINDSTAR
6 CYL
FWD
AUTOMATIC
104,365 MILES

Hi, I have a 1999 ford windstar. When I turn it on it shakes. It will stop is I press on the gas or put it in to gear. It does that some times, not every time I turn it on, but it's getting very frequent. It doesn't matter if I turn it on first thing in the morning or if I have driving it for half a day, it will start to shake any time it wants. It feels like a spark plug problem, but I already put in new spark plugs, cables, oil filter, air filter, and changed the oil. Also, it doesn't have the check engine light on. I will appreciate a lot if some one can help me with this.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,758 POSTS

Hi,

If it goes away when you press the throttle, it sounds like it could either be related to the fuel pressure or the idle air control valve (IAC).

The IAC is responsible for maintaining engine idle speed. If it is failing, it could prevent enough air from getting to the engine at idle. You may want to service it. It will be located on the throttle body.

If you look at pic 1 below, it shows the IAC. It will be at the end of the air induction tube between the air filter box and the throttle body. I highlighted it in the pic.

Here is a link that explains how to service one:

https://www.2carpros.com/articles/idle-air-control-valve-service

Also, you may want to consider checking fuel pressure and pressure drop-off. Here is a link that explains how to perform the procedure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you look at pic 2, it provides the manufacturer's fuel pressure specifications. Pic 3 is the drop-off (leak down) information. This is important because you could have an injector leaking and flooding one of the cylinders.

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below.

Images (Click to make bigger)