Possible Throttle Position Sensor or Idle Control Valve Issue???

[RiskyRick]

My GT recently started doing a couple of odd things-

Firstly, there is a slight stumble at idle. Not a miss, or at least if it is, it is random.

Secondly, while driving, power at a constant throttle position seems to fluctuate.

What the hell is going on? I would think that the icv would cause the idle to hunt rather that stumble every little bit, and I would think that the tps wouldn't have much, if any effect at idle. Any input?

 

[KLeech]

I'd start with cleaning the iac, then check the voltage on the tps.. Should be in the .99 range. And since you said a stumble at idle and inconsistent power that could have something to do with the throttle body. Ever cleaned it?

 

[tobynt]

What year is your car?

 

[tobynt]

My GT recently started doing a couple of odd things-

Firstly, there is a slight stumble at idle. Not a miss, or at least if it is, it is random.

Secondly, while driving, power at a constant throttle position seems to fluctuate.

What the hell is going on? I would think that the icv would cause the idle to hunt rather that stumble every little bit, and I would think that the tps wouldn't have much, if any effect at idle. Any input?

Really need a lot more information. Possibly need you to take a step back and re-group your thoughts.

Right now theirs just not much help I can personally be.

You reference a "stumble" at idle then you reference a "idle hunt".....really need to know if its a "stumble" or if the idle is "hunting". If it is "hunting"...what is the idle "RPM" variation? Also, how rapid is the "hunt". will it continue until it stalls the engine?

You also said "while driving, power at a constant throttle position seems to fluctuate". Need more information. Does the RPM's change during this "noticeable power fluctuation". What is the outside temp when this happens, what is your current operating temp when this happens, Does it only happen on a flat road with no real "load" on the engine or is it only when going up a slight incline with "load"....how much "load".

How many miles are on the car and what year is the car. Whats the last tune up? Have you performed any...again, any engine mods or is it bone stock. Is it an automatic transmission or a manual.

Are you running the heater or the A/C when this happens. Will it happen when you turn on the heater or A?C during both conditions of "Idle" or "driving"? Also, does it happen when neither the heater or A/C is on?

 

[RiskyRick]

Really need a lot more information. Possibly need you to take a step back and re-group your thoughts.

Right now theirs just not much help I can personally be.

You reference a "stumble" at idle then you reference a "idle hunt".....really need to know if its a "stumble" or if the idle is "hunting". If it is "hunting"...what is the idle "RPM" variation? Also, how rapid is the "hunt". will it continue until it stalls the engine?

You also said "while driving, power at a constant throttle position seems to fluctuate". Need more information. Does the RPM's change during this "noticeable power fluctuation". What is the outside temp when this happens, what is your current operating temp when this happens, Does it only happen on a flat road with no real "load" on the engine or is it only when going up a slight incline with "load"....how much "load".

How many miles are on the car and what year is the car. Whats the last tune up? Have you performed any...again, any engine mods or is it bone stock. Is it an automatic transmission or a manual.

Are you running the heater or the A/C when this happens. Will it happen when you turn on the heater or A?C during both conditions of "Idle" or "driving"? Also, does it happen when neither the heater or A/C is on?

Car is a 2002 5-speed w/ 97k miles. Bone stock at the moment.

I was saying that there is no hunt- the idle doesn't fluctuate, but randomly there will be what feels almost like a miss, but isn't. Happens roughly every couple of seconds, but time between varies a bit, making me pretty sure it isn't just one hole. It is audible in the exhaust, but doesn't sound like a miss either, almost sounds like it has a very slight chop.

The power at a constant speed, revs, load, and throttle is what feels like is fluctuating at random intervals. Part throttle light load, any speed.

Engine temp seems to have no affect on either.

Heater and A/C make no difference.

Car never stalls or dies, idle speed always stays were it should be.

 

[tobynt]

Car is a 2002 5-speed w/ 97k miles. Bone stock at the moment.

I was saying that there is no hunt- the idle doesn't fluctuate, but randomly there will be what feels almost like a miss, but isn't. Happens roughly every couple of seconds, but time between varies a bit, making me pretty sure it isn't just one hole. It is audible in the exhaust, but doesn't sound like a miss either, almost sounds like it has a very slight chop.

The power at a constant speed, revs, load, and throttle is what feels like is fluctuating at random intervals. Part throttle light load, any speed.

Engine temp seems to have no affect on either.

Heater and A/C make no difference.

Car never stalls or dies, idle speed always stays were it should be.

Umm...Okay.

really sounds like a tune up is in order. If none of the above "check list" matters. I can't run down a diagnostic for you.

Change you fuel filter, plugs, clean your mass air meter, clean you throttle body, clean your idle air control valve, change you air filter. I would also change the oil while I was at it. After that pull your positive battery cable and reset the computer.

Best of luck.

 

[RiskyRick]

Sorry, forgot to ad, new plugs, air and fuel filters within the last 2k miles. I'll just have to try cleaning the maf, tb, and iac out when I change the oil this weekend.

Thanks.

 

[KITT]

Sounds like your iac needs cleaned. Mine was acting up horribly a few weeks ago. I pulled it off and soaked it with brake cleaner you can use other things as well. This, would be my best guess. I have an 02 with similiar miles. Ford is notorious for iac troubles.

Besides that I would just clean up everything else and disconnect your battery for 20 minutes.