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Discussion Starter · #1 ·
2006 Spectra EX, 5-speed manual, just north of 200k miles
Within the past week or so, I've noticed that, while the gas pedal itself doesn't stick, somehow the accelerator is sticking even after I release it.
I can be in gear (I've noticed in 2nd, 3rd & 4th, and can't tell whether or not it happens in 5th, as I typically have it in cruise control in those instances) and let up off the gas while staying in gear, on a level surface, and the car will continue to coast as though cruise control is engaged and/or I've still got my foot on the gas. Watching the tachometer, RPMs stay steady or even increase ever so slightly in these instances (generally, about 2500-3200).
Other times, if I go to shift into neutral, to coast down a hill or whatever, I can watch the tach and see it increasing or holding steady instead of flipping all the way down to around 800-1200 RPMs (where it usually sits when I'm idling or in neutral). If there's not a ton of noise inside or outside the car, I can also hear it sound as though I'm revving my engine in these instances.
May or may not be related, but on some occasions, when idling at a light or after just starting the car up or parking, it feels as though it's about to crap out on me. Not all the time, but certainly more than it used to (at least once every few trips vs. almost never in the past). Likewise, there's been a couple instances in the past few weeks where it's been a little sluggish to accelerate, but we're literally talking like 2 times driving roughly 300 miles a week now. The only semi-persistent-ish issue I've had with this car, otherwise, is a bad upstream O2 sensor.
What are some potential causes of this issue? I'll admit I'm not as good as I once was about regimented oil changes, so is the problem something as simple as that, or is this indicative of a larger issue?
Thanks to anyone who can help provide some insight.
 

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09 kia spectra ex,'11 Dodge Journey AWD,04 Chry. T&C, 08 Pontiac G6 gt
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First of all, can you tell us if the Check engine light is illuminated when driving? You need to get the codes pulled from the computer and post them here for better help. As you post of a "finicky" upstream O2 sensor...that is a major control sensor for proper engine operation. bad or no proper working from it WILL cause drivability issues.
Next at posted miles, I'd check the motor trans mounts. A broken one will allow the motor to "shift around" causing movement in the throttle cable to throttle body...thus RPM fluctuations.
Looking forward to your response and P format code(S) the car has for us to be able to help more.
 
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Discussion Starter · #3 · (Edited)
First of all, can you tell us if the Check engine light is illuminated when driving? You need to get the codes pulled from the computer and post them here for better help. As you post of a "finicky" upstream O2 sensor...that is a major control sensor for proper engine operation. bad or no proper working from it WILL cause drivability issues.
Next at posted miles, I'd check the motor trans mounts. A broken one will allow the motor to "shift around" causing movement in the throttle cable to throttle body...thus RPM fluctuations.
Looking forward to your response and P format code(S) the car has for us to be able to help more.
As "luck" would have it, the check engine light hadn't turned on prior to my original post, but but came on during a quick trip to the store an hour or so ago.
5 codes total
P0420 Catalyst System Efficiency Below Threshold Bank 1
P0170 Fuel Trim Bank 1
P0171 System Too Lean Bank 1
It also repeats the 170 & 171, but with a " P" after each that aren't separately listed in my scanner's manual.
Incidentally, nothing specifically regarding the O2 sensor.

To add to this comment, yesterday was first time driving in stop-and-go rush hour traffic, and for a part of it I was able to coast down an on-ramp in neutral, and the entire time the car was "accelerating"--slowly revving from about 1000 rpms up to close to 3k, then back down. And more of the other stuff noted in my original post.

What's the likelihood that I'm just needing to replace the O2 sensor?
 

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Discussion Starter · #4 ·
First of all, can you tell us if the Check engine light is illuminated when driving? You need to get the codes pulled from the computer and post them here for better help. As you post of a "finicky" upstream O2 sensor...that is a major control sensor for proper engine operation. bad or no proper working from it WILL cause drivability issues.
Next at posted miles, I'd check the motor trans mounts. A broken one will allow the motor to "shift around" causing movement in the throttle cable to throttle body...thus RPM fluctuations.
Looking forward to your response and P format code(S) the car has for us to be able to help more.
To add some additional information:
Drove just fine yesterday, and Check Engine Light turned off. Same the entire way to and from work today (roughly 120 miles total both days). Of course, about 45 minutes after getting home from work, I turn around to go pick my daughter up from school--about 1 mile round-trip--and I was noticing the same problems as described in my initial post, and the Check Engine Light turned back on right before arriving at home. I let idle in my driveway for a couple minutes after getting home, but of course it wouldn't do the spontaneous "acceleration" thing, so I couldn't observe the engine in action, at least doing anything out of the ordinary.
Where would I be looking for the motor trans mounts? Is it something that would be visible from above, or would I need to get underneath to view? I'm no car whiz, but I'd rather avoid taking somewhere to get this looked at, if possible, because I've had trouble finding a place near me that doesn't have a 2-week waiting list for an appointment that doesn't feel like they're trying to gouge you.
 

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09 kia spectra ex,'11 Dodge Journey AWD,04 Chry. T&C, 08 Pontiac G6 gt
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So you've done nothing since your last post? Granted there was no direct O2 code you posted, BUT those shown COULD still be a upstream O2 OR intake or exhaust leaks that WILL give the codes posted. A 200K mile car and we don't know what maint the car has (or has NOT) had to offer more help. Diagnosis by your symptoms does not go very far when not checking other items of normal maint by mileage(plugs, wires, throttle body/IAC operation).
 

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Discussion Starter · #6 ·
So you've done nothing since your last post? Granted there was no direct O2 code you posted, BUT those shown COULD still be a upstream O2 OR intake or exhaust leaks that WILL give the codes posted. A 200K mile car and we don't know what maint the car has (or has NOT) had to offer more help. Diagnosis by your symptoms does not go very far when not checking other items of normal maint by mileage(plugs, wires, throttle body/IAC operation).
I replaced O2 sensor this morning, then drove around running errands, plenty of stop-and-start driving, no appreciable difference than before.
I'll just relate something odd but don't expect any response or anything. But, basically, the car seems to run fine on Wednesdays and most of Thursdays. The past few weeks, my work schedule has been as follows: Off Tuesday, Work early AM Wednesday and Thursday (early enough to avoid any stop-and-go rush hour traffic on the way to and from work). The first Tuesday, the weather was crummy and I didn't drive anywhere; car ran fine with no check engine light that Wednesday, and most of that Thursday, up until the last leg of my driving for the day (about 2 miles round-trip to pick my daughter up from school). I thought, "hey, maybe letting it sit for 24+ hours helped?" But I've had multiple weekends off since (usually drive my wife's car then), and that hasn't seemed to make any difference come Monday morning. Anyway, the subsequent Tuesdays off, I've done some driving around--some stop-and-go on residential and secondary roads, a little bit of interstate speeds--and each Wednesday, the car has run fine; each Thursday, the car has run fine up until the couple of miles closest to home. Anyway, it's probably nothing but I found it amusing nonetheless. Guess I'll be calling around to see if anyone can squeeze me in to have a look over the next few days.
 

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Self rising throttle (without pressing the pedal) is indicative of a dirty or malfunctioning Idle Air Control solenoid mounted on the throttle body. Because it only does it intermittently, I would suspect removal and a good cleaning would take care of it. Once again CEL? and What P format codes are showing up?
 
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