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engine idle Pulsing


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RodmanB
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Jun 4, 2011, 9:06 PM

Post #1 of 12 (5678 views)
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I have a ‘03’ Ford Taurus SES with a 3.0L V6 and 123K miles. When idling through say a neighborhood or school zone the engine RPM pluses from 400 to 1400. Up and down, Up and down, Up and down, unless it dies. If it dies I can restart it but, sometimes it dies again. If it does I have to turn the key to off before it will start again. It does the same thing when coasting up to a stop light or sign, but once stopped, it levels off. I just replaced the catalytic converter because the engine light said it was bad, however the engine light is NOT on now. I’ve also notices on the Hwy. when I let off the gas pedal and then press it again it will hesitate. I’m just looking for information and suggestions. If you’re a mechanic looking to supplement you income never mind. This is the information Highway not an opportunity to make money from my dirty hands. However, I will greatly appreciate any knowledge sharing offered.


(This post was edited by RodmanB on Jun 4, 2011, 9:10 PM)


Hammer Time
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Jun 4, 2011, 9:17 PM

Post #2 of 12 (5666 views)
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  You may have a bad IAC ( idle air control) but try eliminating any vacuum leaks and cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



zmame
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Jun 4, 2011, 11:23 PM

Post #3 of 12 (5649 views)
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if the old converter came apart there is also a change that the muffler is plugged with the crap from the old converter restricting flow at times.


RodmanB
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Jun 5, 2011, 1:38 PM

Post #4 of 12 (5639 views)
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Thanks for your reply, I really appreciate it. However, just before I read your post I went to the store and the engine light came on. I had it scanned today and it reported "O2 Sensor". So I guess I should replace that before moving on to your suggestions. Again, thanks for the help.


Hammer Time
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Jun 5, 2011, 1:40 PM

Post #5 of 12 (5636 views)
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No, you shouldn't That code doesn't mean "change the sensor". It needs to be diagnosed correctly. What was the exact code number?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



RodmanB
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Jun 5, 2011, 2:14 PM

Post #6 of 12 (5632 views)
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P0420 - Catalytic efficiency low bank 1


Hammer Time
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Jun 5, 2011, 2:17 PM

Post #7 of 12 (5628 views)
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And you think that code means change an 0/2 sensor?

That is nearly always a bad Catalytic Converter and rarely has any effect on engine performance.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



RodmanB
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Jun 5, 2011, 3:29 PM

Post #8 of 12 (5621 views)
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My thinking is irrelevant, I'm on the internet get advice from strangers, that alone says my thinking is flawed. I'm just going by the code and description generated at the local Auto Zone. Your conclusion "nearly always a bad Catalytic Converter" is interesting, seeing as how I just replaced the Catalytic Converter last week in hopes to correct the idle problem. I guess I'll just sell it and go back to riding the Bus like I've done for the past 3 years.


Hammer Time
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Jun 5, 2011, 3:31 PM

Post #9 of 12 (5618 views)
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Why was the converter changed? Was the computer cleared when that repair was made?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



RodmanB
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Jun 5, 2011, 4:11 PM

Post #10 of 12 (5611 views)
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Auto Zone, and Salinas Muffler Shop said that was what the check engine code said. And, Yes the light was cleared. It has seemed to preform better and labored less on acceleration since the CC change. It's also died less since the change.


Hammer Time
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Jun 5, 2011, 4:13 PM

Post #11 of 12 (5609 views)
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Then I would bring it right back to them. You have the same code and the Converter is under warranty.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



RodmanB
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Jun 5, 2011, 4:16 PM

Post #12 of 12 (5603 views)
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Fine. Thanks for the suggestion.




engine idle Pulsing


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