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Idle Car RPMs are way too high


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#1 Kondrath

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Posted 01 September 2010 - 22:24

First off, I'll apologize. You know those people who don't know anything about computers, who can't even tell you how many gigs it has, and say things like "My computer has 6 Gee Bee's and a few RAMs of memory" ? Well, I'm the automotive equivalent of that...

Today I noticed that when I turned the car on (1994 Ford Tempo), the RPM's were way too high, as if I was holding down the gas pedal. I don't have an RPM meter on the dash, so I can't give specifics. But it is definitely higher than usual. If you give it a little gas, it gets very loud and takes a long time to go back down to "normal" RPMs. But in this case, normal RPMs are still too high.

Gas pedal isn't jammed. The throttle/accelerator thing isn't jammed either. Umm, the "choke" (I think that's what it is?) is also fine. My dad and I looked at it but didn't see anything out of the ordinary. Then it just so happened that my uncle who runs a car repair / towing business was right down the block. He checked it out and said that it might be a vacuum/valve leak. But we couldn't find anything.

Then he said it could be the idle control valve / sensor.

When you put the car in drive, it goes back down, but you've gotta keep your foot on the break or else it'll take off faster than usual. While driving, it's like I have automatic cruise control. Speed won't drop unless I brake. And as soon as you put it in park again, the RPMs climb back up very fast, so I turn it off quickly.

I think we're going to check for leaks again later, but until then, just thought I'd ask for opinions.

OH, this may also be of importance, but I noticed that I was a little low on gas, so I went to fill it up. When I unscrewed the gas cap, a bunch of air shot out of the tank. That never happened before. Not sure if it's related or not.

So, yeah :wacko:


#2 xendrome

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Posted 01 September 2010 - 22:30

Could have an O2 or similar sensor going bad, and it's thinking the mix of air/fuel is off, so it's compensating by increasing the idle to keep the car from stalling. When it's readings are infact bad, and the fuel mixture is fine.

Also it could be the idle control valve / sensor.

#3 OP Kondrath

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Posted 01 September 2010 - 22:36

Could have an O2 or similar sensor going bad, and it's thinking the mix of air/fuel is off, so it's compensating by increasing the idle to keep the car from stalling. When it's readings are infact bad, and the fuel mixture is fine.

Also it could be the idle control valve / sensor.


Ah, THAT's what my uncle mentioned. Not sure where I got "intake motor" from, LOL.

Thanks for the suggestions, I'll forward them to the people who know more than I do.

#4 MR_Candyman

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Posted 01 September 2010 - 22:45

Xendrome hit the mark

#5 redvamp128

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Posted 01 September 2010 - 22:46

He probably said== Mass Airflow Sensor- is possibly what he said-- I would say it is probably your Throttle position sensor going bad---without seeing the car.

I would probably take it to a shop-- unless you want to be replacing parts left and right.




#6 andrewbares

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Posted 01 September 2010 - 22:50

Yeah, we have a Toyota Celica 2002 that idles different than it used to, and the shop says that it probably has a bad O2 sensor. A bad O2 sensor of course triggers the Engine Light too.

#7 micro

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Posted 01 September 2010 - 22:51

if the car is also overheating, it can be a good indication of a bad O2 sensor.
There could also be other problems such as misfiring sparkplugs or slipping timing belt.

etc, but as said. Take it to a shop to have them "Asses" what they think the problem is and a quote of what it would cost to replace.

That way you know for sure what the problem is. Guessing and replacing parts can be costly.

#8 OP Kondrath

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Posted 01 September 2010 - 22:52

Yeah, we have a Toyota Celica 2002 that idles different than it used to, and the shop says that it probably has a bad O2 sensor. A bad O2 sensor of course triggers the Engine Light too.


My engine light isn't on, though.

I'm gonna check the idle control valve / IAC in a bit.

I'm not too sure about the throttle position sensor. My dad isn't exactly a mechanic or anything, so he wouldn't even know where to look to find most of this stuff. Specifically the O2 sensor.


@Micro, the car isn't overheating, but it is hotter than usual. However, it's staying within the normal range and hasn't come close to the red / dangerous temp levels.

#9 timmmay

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Posted 01 September 2010 - 22:53

I've had this happen in two previous cars that I've owned and both times it's been the oxygen sensor!

#10 OP Kondrath

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Posted 01 September 2010 - 22:56

I've had this happen in two previous cars that I've owned and both times it's been the oxygen sensor!


Good to know. So it's most likely one of these goofy sensors dying on me :p

#11 xendrome

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Posted 01 September 2010 - 22:58

Good to know. So it's most likely one of these goofy sensors dying on me :p


yea, the problem is those goofy sensors are usually expensive... :(

#12 OP Kondrath

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Posted 01 September 2010 - 23:00

yea, the problem is those goofy sensors are usually expensive... :(


My uncle has a 93 Tempo with no title that he had to tow earlier in the year; maybe I can just swap with the parts from that one? Unless of course, it's the labor that jacks up the cost and not the part itself..

#13 wrench

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Posted 02 September 2010 - 02:47

Sounds a lot like a vacuum leak. If it's not obvious, maybe it's the intake manifold gasket.
Unplugging the idle air bypass valve while the engine is running should cause the engine to slow down or stall on a working system. If there is a vacuum leak or the valve is sticking, it may have no effect.
Just something to try.

#14 strekship

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Posted 02 September 2010 - 18:40

My car had a similar problem. Turned out a few of the cables that go from the sensors to the PCM had been damaged. I believe that it was the TPS that was causing that specific issue.

#15 OP Kondrath

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Posted 03 September 2010 - 17:22

Okay, well it turns out my dad doesn't know where ANYTHING is. I took some pictures just in case you guys could help, but most likely I'll end up taking it to my uncle's shop.

Where is the Idle Control Valve? The Idle Air Bypass valve? the TPS? Is it possible to even see in these pictures?

Also, would the O2 be underneath the vehicle?

Sorry for the noob questions, but I really do feel like I'm picking up on this quite fast. Same way I learned about computers; had them go bad on me and the internet helped me identify problems, etc. :p

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