2000 Mercury Sable Engine Hesitation

Tiny
ATIREIRON
  • MEMBER
  • 2000 MERCURY SABLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 197,000 MILES
I've noticed over the last week or so that my engine hesitates, sometimes on acceleration and sometimes when my speed is steady. I haven't noticed it on deceleration. It's worse when the engine is cold, but still happens after reaching operating temperature. Over the past two days the hesitations have become significantly more frequent, as in, I feel it several times in ten miles, as opposed to once or not at all in ten miles like it was a week ago. I haven't noticed any strange sounds, rattling, groaning, squeaking, anything like that, but I have noticed that my rpms don't seem to fluctuate when the car hesitates. I've also noticed that sometimes the transmission seems a little sluggish when shifting between 1st and 2nd gear, and 2nd and 3rd gear, and is sometimes a little rougher than usual between 3rd and 4th, and 4th and 5th. However I can't tell if this is because there's a hesitation at the same time of the shifts or not. It does not happen all the time and doesn't SEEM to be an independent problem, but who knows. I can't think of what could possibly be going on that would cause that kind of a symptom without also causing the rpms to fluctuate, either up or down.
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Saturday, December 26th, 2009 AT 2:27 PM

3 Replies

Tiny
RASMATAZ
  • MEMBER
Hi atireiron, Welcome to 2carpros and TY for the donation and selecting us as your auto repair site Feel free to ask questions at anytime and Merry Christmas and a Happy New Year 2010

Do you have a CEL and also when was the last tune-up?

Check and test the following:

Oxygen sensor
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/high resistances
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Saturday, December 26th, 2009 AT 5:01 PM
Tiny
ATIREIRON
  • MEMBER
I don't have any warning lights at all right now, either check engine or otherwise, and my last engine tune-up was 50,000 miles ago. I'm guessing there's a possibility this is simply because it's been too long between major services. Also, my fuel pump failed and I had to have it replaced about two weeks ago. I'm guessing there's also a possibility that replacement has something to do with this?

Thanks for all the info. It's nice to have an idea of what could be going on. Merry belated Christmas and Happy New Year to you as well. :-)
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Saturday, December 26th, 2009 AT 9:13 PM
Tiny
RASMATAZ
  • MEMBER
I'm guessing there's also a possibility that replacement has something to do with this?

Won't hurt to check and verify the fuel pressure if its within specs
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Saturday, December 26th, 2009 AT 9:17 PM

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