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:confused: car seems to hesitate before she goes-new plugs wires cap and rotor , anyways the o2 sensor on drivers side is broke and loose. is that enuf to make my car hesitate? im gettting ready to change but want to know if anyone has any other ideas or input:confused:
 

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:confused: car seems to hesitate before she goes-new plugs wires cap and rotor , anyways the o2 sensor on drivers side is broke and loose. is that enuf to make my car hesitate? im gettting ready to change but want to know if anyone has any other ideas or input:confused:
yes, it's enough to cause a multitude of issues with how the car runs once warm.

Jody
 

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dirty maf sensor could be an easy fix....
 

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bad 0/2 sensors dont make a car hesitate. unless maybe if it is hot.maybe look at map or mass or temp sensor.or if you got a k&M oil filter and you put to much oil in there.

once the car is warmed enough to switch to closed loop a bad O2 can definitely make a car hesitate, stall, run rich/lean, etc.

Jody
 

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also changed the o/2 sensor-still does it a little-does my car have an idle control valve? or what
You should have an IAC, it would be located on the throttle body. On a GM it's usually a round valve/motor with a 4 wire square plug.

Have you changed your fuel filter lately? That will definitely affect fuel pressure if it's dirty which would result in a lean condition, hesitation, pinging, etc.

Jody
 

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We could help more if we knew what kind, year, model, and engine of car you are working on. Why is the o2 loose?
What kind of maintanence has the vehicle seen?
I would guess a bad maf, if the vehicle you are working on has one.
Could be ignition or a base fuel supply problem.
Could be the computer is bad
Could have any amounts of bad connectors, or wiring.
Could have a bad engine or trans.
I've even had a bad battery make the car hesitate
 

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Ohhh, I see your other post, a tbi car, check the map, is it getting manifold vacuum to it all the time. The throttle body vacuum port for the map cokes up on these. If it's restricted would definately make it hesitate, along with a ton of other stuff.
 

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An O2 sensor doesn't respond quick enough to capture the instance when you step on the gas to go. The O2 sensor does a better job of reading the steady state mixture. The computer is programmed to zap the mixture up when the throttle positon sensor changes.

BUT

If the engine can't get the mixture in the ball park due to a bad O2 sensor, it's estimates of how much fuel to add when you step on the gas can be off. Replace the sensor for starters. Chances are it won't fix your problem. But anything you try to repair without a working O2 sensor may result in other issues that make you chase your tail.
 

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An O2 sensor doesn't respond quick enough to capture the instance when you step on the gas to go. The O2 sensor does a better job of reading the steady state mixture. The computer is programmed to zap the mixture up when the throttle positon sensor changes.

BUT

If the engine can't get the mixture in the ball park due to a bad O2 sensor, it's estimates of how much fuel to add when you step on the gas can be off. Replace the sensor for starters. Chances are it won't fix your problem. But anything you try to repair without a working O2 sensor may result in other issues that make you chase your tail.
he already replaced the O2 which helped but did not eliminate it completely. An O2 that's broken/loose as he stated should be the first thing to fix, as no matter what it can cause issues and needs to work correctly.

By the way, I have personally witnessed an O2 swap fix a hesitation twice already. Of course the car was super lean with the O2 reading wrong, so even though it had acceleration enrichment built into the tune, it was so far off it hesitated anyway.

Jody
 

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Here’s a quick check you can use to check for a
faulty TPS: First, with the engine and ignition off,
unplug the electrical connector and attach an
ohmmeter between the center terminal and one of
the outer two terminals on the TPS.
Manually operate the TPS by s-l-o-w-l-y opening
the throttle. Note the ohmmeter reading. It should
increase or decrease smoothly as you exercise the
sensor through its full range of travel.
Next, connect the ohmmeter between the center
terminal and the other outer terminal. Repeat the
same test. The ohmmeter reading should again rise
or decrease smoothly as you exercise the sensor.

You should also rev the engine while observing the
primary pattern to make sure swell lengthens
(increases) as rpms go up, and shortens (decreases)
as rpms go down.
 
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