Mechanics

ENGINE

2007 Ford Focus • 170,000 miles

Everytime I hit my brakes my car cuts off, sometimes I can be sitting on a hill at a stop light and it cuts off, but it starts back up every time. I have every possible part to fix it any help would be great. Thanks leanna
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Leannag
October 6, 2013.




Everytime you hit the brakes it cuts off? Im assuming it shuts off. If your driving at 40mph for example, and hit the brake pedal to slow to 30mph, does the car still shut off, or is it only doing it when your stopped with your foot on the brake? Do the RPM's drop slowly before it dies? Also, if you step on the gas before it dies, can u keep it running?
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Madmike1735
Oct 6, 2013.
Its when I'm stopped or the car is sitting on a incline. If I hit the gas before it starts to die it is fine. I have replaced fuel pump, air filter, brake line, checked air intake and none of it helped. The rpms do not drop it just cuts off as if I turned it off and for the most part it starts back up without a problem, sometimes it takes a few tries as if its flooded. Thanks so much

Tiny
Leannag
Oct 6, 2013.
Ok, this info will get us a good start. Is your check engine light on? Why did you replace the fuel pump? Was the fuel pressure low, or it was inop? You mentioned you checked the air intake. Do you mean the throttle body? Its hard to inspect an intake unless its off the car. So far, with the info you have given, im leaning towards the Idle Air Control solenoid.

Madmike1735
Oct 6, 2013.
We thought it may of been the fuel pump, but we haven't checked what you are leaning towards what does that do?

Tiny
Leannag
Oct 6, 2013.
It controls your idle speed. It will be located on your throttle body. They sometimes get clogged with carbon, and it prevents the pintle from closing completely.

Madmike1735
Oct 6, 2013.
My husband said they checked that and it was fine we haven't tried the intake manifold gasket and fuel injectors could it be either of these?

Tiny
Leannag
Oct 6, 2013.
How did they check the IAC? An intake manifold gasket would cause an unmetered air leak, and increase idle. A bad fuel injector would give a misfire. Im still leaning towards the IAC. They are a pretty common failure.

Madmike1735
Oct 6, 2013.
While the problem is occurring, keep the engine running by giving it just enough throttle to keep it from stalling. With the Idle Air Control (IAC) valve connected, monitor the voltage across the 2 wires at the IAC valve connector. The higher the voltage, the harder the Powertrain Control Module (PCM) is trying to raise the idle. Expect more than 4 volts if the idle is lower than normal. Then, with the engine running at a low idle speed, unplug the connector, and if the RPM does not drop when the connector is unplugged, replace the IAC valve.

Madmike1735
Oct 6, 2013.
When its on a incline, it starts shaking and then cuts off could that be a misfire?

Tiny
Leannag
Oct 6, 2013.
It sounds like it is. If you have access to a snap on modis, or an OTC genisys, you can get into mode 6 data. Check monitor $53 as on a ford, this is the misfire monitor. There will be more of a load on the engine on an incline, but the shaking could also be the rpms dropping under 500, and then it stalls.

Madmike1735
Oct 6, 2013.

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