2000 Ford Focus Stutters, Shakes

by Sasha
(Marion, Ohio)

It stutters bad. When I start it, sitting still, accelerating(99%of the time), I can't use my air conditioner because it stutters so bad it doesn't want to go. When I accelerate it shakes bad but eventually quits and while im going it doesn't stutter just when accelerating. It doesn't die out it will idle down and kick back up, thats the best way I can explain it. I have replaced spark plugs, wires, coil pack, o2 sensor. I have tried fuel injection cleaner that you pour into gas tank. Nothing works. At one point after replacing the spark plugs multiple times I put a new pair in and it stopped for maybe 6 or 7 months and it drove pretty good but started right up again and now spark plugs ain't fixing it. It does it real bad when its raining. It started when a hose broke off and my car overheated really bad while I was driving it but I fixed that and then it started so I don't know what it is or what to do. Can you help?

Steve Says,
Hi, Sasha. Thanks for visiting my website. If you find it useful please "like" it and share with your friends!

As far as your car question goes, I'll do my best to help you out and give you some advice. There are several things that could be going on here. The first thing that worries me that I see is that this problem started after your car overheated "really bad". This tells me that the problem might be a bad head gasket. Sometimes when a car overheats and the head gasket goes bad it will cause coolant from your radiator and cooling system to leak into the cylinders in your engine and cause them not to fire normally. This might be why you feel the car shaking because one or more of the cylinders is not firing.

I think this is where I would start. To diagnose this problem you can do several tests. The first test I would do will test for exhaust gasses in the coolant. You will need a block test kit that you can get from my Store. This is basically a tool that you put into the neck of the radiator then start the engine and let some of the air in your radiator go into the tool. It has fluid in it that will change color in the presence of exhaust gasses. It is a quick and easy test and one that usually works well.

The other test that you can do is called a cylinder leak down test. You will need a leak down tester that you can also find in my store. You will also need a source of compressed air. This tester puts compressed air into the cylinder when it is at tdc. Then you listen at the oil fill area, the radiator and the exhaust to see if you hear leaking air. If the head gasket is bad you should see bubbles in the radiator. This means that the air is going into the cylinder through the bad head gasket and into the cooling system.

Other things you might be noticing if the head gasket is bad. Excessive white exhaust, engine overheating or heating up more than normal, a lot of water coming out of the exhaust.

These are the two tests I would do first, there are other things that could cause a problem like this, but these tests will narrow down the most likely causes.