[JonNX]

Hi
I have an Focus ZX3 2003, 66160 miles, automatic, great condition but problem started about a 2 months ago. When i've come to a sudden stop/braked sharply the engine judders and sometimes cuts out completely. It had done it several times in the last few months.
Last week I needed a oil change, took the car to a local Midas and mentioned this issue in case something was noticable in the check.
They called and mentioned the battery was running very low and could be the problem (having replicated the stalling) due to inadequate current from the battery. I got them to put in a new one and they couldn't stall it again however on my way home from work today it happened again.
So, any ideas on what this could be? I have a extended warranty on my car but it'll cost $80 to get standard tests done to figure it out (which i'll get back if there is a covered fault) but my concern is what if its something that isn't covered or they can't find the cause.
I'm thinking i'll just drop it off next week anyway but i'm curious as to what could be up with it.

Any help much appreciated!

 

[iminhell]

Why did you buy a warranty if you're afraid to use it?
Use that sucker to it's fullest, don't pay for something and just let it take money from you.

My guess would be a bad brake booster, booster check valve or vacuum leak in that line.

 

[JonNX]

Oh i'll use it and i'm thankful its still valid, won't be able to drop it off till the end of the week and wanted to be prepared for what may be found. Spoke to the service dept at my dealership and they weren't aware of anything like I described, thought if I had some ideas from people here I may be better prepared.

 

[sunyfoci]

keep us updated my car stalled on me once and the idle goes crazy low when i push the brakes

 

[whynotthinkwhynot]

Before you go thinking it's anything else, try this. Get some carb cleaner and a rag. Remove the air intake tube from the throttle body. Now spray the cleaner on the rag, and wipe it around on the inside of the TB. Continue doing this until you've removed all the black there. Especially clean the throttle plate around the hole in the plate. Use a Q-tip to insure you've cleaned that hole completely. Now, reconnect everything, and drive the car until it's warmed up. Afterwards, park it and remove the neg terminal from the battery. Wait 10 mins or so, maybe a good time to clean your battery terminals (I use Windex and a rag) then reconnect and tighten. Now, start the engine, but do not touch the accelerator at all. Allow the car to idle for 5-6 minutes. The ECU will actually time the idle for 5 mins after it drops out of startup idle, and reset the air fuel ratio during this time. If you have a tach, you can watch the idle fluctuate slightly during this time, and when it's finished, the idle will drop down.

If that doesn't fix the problem, try this test: start the engine, allow it to warm up to normal temperature (drive it, then stop somewhere), now crank the wheel while sitting all the way to one side or the other and see if the idle drops to the point where the engine shakes the car like you described. If it does, you can either replace the IAC, or remove it and clean it to see if that will fix it.

 

[JonNX]

I have to apologise, I have no real car knowledge. Can you easily explain where these engine components are or should I look for details?

I thought connections but I had a maintenance chekup last week (and new battery installed) at a Midas and think they would have spotted any issues or corrosion...at least I hope they would have.
I'll try the idling test this evening though.,

thanks!

 

[sunyfoci]

the black build up on the throttle body is carbon, your throttle body should be right behind the valve cover in the middle where the throttle cables are hooking up and your intake tube ends. As for the iac valve its going to be impossible to get at from above because it is below the throttle body between the engine and intake manifold so you need to get at it from under the car and even then its difficult.

 

[JonNX]

I'll take a look at the former tonight.
I'm thinking back now and trying to see if theres a pattern between the stalling and the fuel level, I think it happens when the gas tank is low on fuel. Been reading around and that seems to be something that can exacerbate the problem.

 

[carguychris]

My guess would be a bad brake booster, booster check valve or vacuum leak in that line.

+1. Check the following:

1) Does the idle quality or engine RPM change in any way when you apply the brakes with the transmission in Park?

2) Open the hood and have someone listen carefully to the area around the driver's side firewall when you do this. A faint "hisssss" that starts when you apply the brakes is a hallmark of a bad booster or vacuum line.

Regarding the battery problem, do any of the car's other electrically operated features (starter, headlights, dash lights, radio, etc.) do anything strange while the car is stalling? One of my old cars would stall and the entire electrical system would go dead, then everything would come back on. It turned out to be a bad battery terminal.

 

[revolution9]

any update on this????

mine is doing the same thing. i changed the vac line and still...stalls at braking sometimes.

 

[JonNX]

any update on this????

mine is doing the same thing. i changed the vac line and still...stalls at braking sometimes.

It actually stopped doing it, didn't do a thing. It was more prevalent when the gas tank was low, think there is a known problem with the fuel tank in this car thank can occur esp after a collision accrding to my service centre. I was waiting to see if it crops up again b4 i posted to give anymore info. At mo its fine.