Mechanics

A/C CAUSES ENGINE HESITATION

2001 Ford Focus

Engine Performance problem
2001 Ford Focus 4 cyl Front Wheel Drive Automatic 87,800 miles

Hi, my name is Jonathan, I have a 2001 Ford Focus ZX3 with 87,800 miles on it. Problem: My car hesitates and has trouble switching into higher gears whenever I turn on my A/C. A couple of months ago, it had the same problem, but worse, it actually turned off on me - I put in Mobil 1 10W-30 High Mileage Fully Synthetic oil, and reset the car's electronics by taking the battery out for 2hrs, which made the problem disappear. But now it is back again, but it is not as bad and has not shut down on me yet. It is an automatic transmission type.
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BiblosLXX
June 21, 2009.




Do you have a check egnine light and when was the last tune-up?

Possible causes for hesitation or stumbling: Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include: Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

Tiny
Rasmataz
Jun 21, 2009.
Thank you for your speedy answer, it has a lot of info for me to work with. The Engine light is on, and sometimes it blinks and when it does blink it always goes back to solid after a minute of blinking (this is during my driving).

I don't know what a tuneup is, but I change my own oil, oil filter, and air filter. I bought my car used at around 35,000 miles, and since then I've only had the regular " tune-ups" like brake-pad change, wheel rotation, and oil change.

Also, my fuel cap light is always on. But I think that may be a small minor thing, I might have to buy a new cap is all. But besides that, no other lights are on, and the A/C works great even though the car seems to hesitate.

Tiny
BiblosLXX
Jun 21, 2009.
It's been a month since I last updated this question: The CRUISE CONTROL is no longer working, and I now notice that my car engine hesitates when it rains or when I have the A/C on. If I drive it too hard while under these conditions, the car turns off. Can anyone narrow rasmataz's diagnosis? Or offer the correct diagnosis? Please read all my posts (2) so that you are fully informed, I have donated money!

Tiny
BiblosLXX
Jul 24, 2009.
The Engine light is on, Is this the check engine light? If so you need to have the computer scanned for code/s. Furthermore have you checked all the items I've mentioned earlier. Its very critical that you do, to narrow down the problem and comeback with some results

I don't know what a tuneup is: with the mileage you have 88K's miles and bought at 35,000 miles and you haven't done a tune-up
since you got this vehicle I recommend a tune-up be done.

The word " tune-up" actually applies only to older cars, on which you can perform the traditional work associated with the term-spark plug replacement, ignition contact point replacement, dwell adjustment, ignition timing adjustment and carburetor idle and mixture adjustment. For most of today's cars, "engine performance maintenance" is a more accurate term. All modern cars and light trucks are equipped electronic ignition (no points) and at least one on-board computer that automatically adjusts items like the ignition timing, fuel mixture and idle speed. In fact, on modern computer-controlled cars, it's impossible to adjust these yourself.

An automotive tune-up is an orderly process of inspection, diagnosis, testing, and adjustment that is periodically necessary to maintain peak engine performance or restore the engine to original operating efficiency.

Tiny
Rasmataz
Jul 24, 2009.
My car is now at 105,738 miles and its giving me a hard time. I am going to be extremely descriptive in hope for a narrow diagnosis and remedy.

1) The car hesitates when I accelerate fast, but it does not hesitate when I accelerate really slow.
2) The car hesitates more often when I drive it in the rain.
3) If the car begins to hesitate, I can press the " Overdrive" button (which prevents the car from going into Overdrive) and the hesitation is reduced immensely, sometimes it goes away completely.
4) If I start the car in 1st gear, then manually move it to 2nd, and then manually move it to " D" drive, then manually turn on the " Overdrive" feature after 45mph to get it to higher gears, then I can reduce the hesitation because I am manually shifting the gears instead of leaving it to the car.
5) I bought brand new top of the line electric spark plugs which reduced the hesitation for a while, but now it is back.
6) I also bought brand new electric spark plug wires at that same time.
7) Driving my car in the rain with the A/C will make the hesitation so bad that it turns my car off.

SO, the fact that the car hesitates more often in the rain makes me feel like it may be that a sensor may be messed up that regulates gas/air ratio. The fact that manually switching my car makes it easier to drive, and the fact that the A/C turns off my car tells me that I also have a power problem, but I don't know where it is coming from.

It's not a dirty fuel injector, its not bad spark plugs or wires, and its not bad oil, oil filter, or air filter.

I don't know, you guys are the pros, help me out! I am giving $5 now to see if this is legit, but if anyone helps me out I will gladly give $50-100 if it is a precise and true explanation of what is going on. If even after this explanation you still don't have enough info, just let me know and I'll try my best to give more.
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Tiny
BiblosLXX
May 18, 2010.
Raz suggested you get the codes read, I say it's not a suggestion, it's mandatory, Autozone reads them free, get the code(s) read, this will let you know what the PCM(brain) thinks is wrong, drive as little as possible, when the engine light blinks, you are misfiring and could be damaging the catalytic converter. Post all codes found.

Merlin2021
May 27, 2010.

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