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Discussion Starter #1
me again guys. After I got the egr valve replaced, the check engine light went off...for a while, and didn't have the $$$ to get it inspected in that time. Suddenly One day I turned it on and it reved instead of idled. I pushed in the wire connected to the throttle PS and it started to idle, but the light stayed on. A month or so later I started to get times when i'm driving on the highway and suddenly the speedometer starts to fluxate drastically, gears start to shift slightly up and down

I got my oil changed today and the guy said the piece of plastic on the tps that hooks to the connector was loose. He tightened it as much as he could. Reset my codes, and on my way back I was on the highway, suddenly my speedometer hit 0, and it shifted to 1st gear, and stayed there, for a good 10 seconds as I started to slow down, it then jumped back up to 60, shifting back up quickly as it did. Could this be related to the TPS? transmission position censor?

thanks
 

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LIFETIME HILLBILLY
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It downshifted to 1st going 60?
 

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LIFETIME HILLBILLY
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Not trying to scare, I've had mine to 45 in 1st going down a kiss your a$$ goodbye steep hill. I just would't figure the transmission would do it, even while having issues. Possibly faulty pcm (7th gen)/tcm (8th gen)?
 

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Discussion Starter #7
yeah I was going from i20 to 287, wasn't on the highway but the connector. Scared the shit out of me and I slowed down as much as I could, I was about to pull over then suddenly it went back up

the guys at the car place are just :WTF: when I told them. They had no idea what it could be and they know a fair amount (this is a oil change/inspection and _light_ service place)
 

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8th Gen Antagonist
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I second Jemima on the speed sensor, it makes the most sense.
 
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Hazardous Materials
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I'd look at the tps. It does send signals for gear shifting
 

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I'd look at the tps. It does send signals for gear shifting
I always thought TPS was Throttle Postion Sensor...:dunno:

And, I was wondering if THAT could be part of the problem too...making it rev...
 

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Hazardous Materials
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I always thought TPS was Throttle Postion Sensor...:dunno:

And, I was wondering if THAT could be part of the problem too...making it rev...
yes tps is throttle position sensor

it could very well be
had a customer complain their car wouldnt downshift (2002 century)

the tps was the culprit
 

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Discussion Starter #12
TPS could also be transmission position sensor, which is why I specified throttle PS

ok, I stand corrected, but this getting wierd, and i'm getting scared

it does not go into first, it goes into neutral. Its done it 3 more times..but heres the thing, it does it in the SAME PLACE. Going listing lazily to the left, at about 80% on the onramp from 20-west to 287-south. It hits 0, and goes into neutral for a few seconds. Just to test it out, I put it in neutral when I got into 287, sure acted the same way.
 

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Discussion Starter #13
ok this problem is getting worse. When my steering wheel is in the middle or left the speedometer begins to fluctuate, and the gears shift erratically, if its turned to the right, it hits each gear hits perfectly

I already took it to one of the best places I know they they just could not figure it out, they called everyone they know and no one had ANY idea what it could be. they told me to take it to a chevy place :(
 

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Hey Uranium-235,

Sorry to hear that they weren't able to figure out what was causing the speedometer to fluctuate. Well, hopefully the dealership is able to find the cause of your concerns. Best of luck.

Amber N.
Chevrolet Customer Care
 

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Discussion Starter #15
even the guy at vandergriff told me he never heard of such a thing in his life (and hes been working there a long time)

I posted it on yahoo answers and so far the only response I never thought about or heard is this:

"Your engine may be moving around due to old engine mounts, have them inspected / replaced. My 2000 Olds needed them a few years ago. Yours are probably bad. May cause issues you describe."

the guy at the first shop told me my mounts definitely needed to be replaced, but wasn't sure that was causing the issue
 

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8th Gen Antagonist
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What would that have to do with anything? The speedo and shifting is all electronic.
 

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no kidding. The mounts have nothing to do with your throttle position or your irractic shifting. I still say speed sensor.
 

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Discussion Starter #18
and GM agrees with you, they also add throttle body (which i'm not sure that was one of the reasons for the steering issue or not...but it was never replaced and the car is 14 years old). There was also a 3rd part they said on the phone. I don't remember what it was

ether way, i'm down $1200
 

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8th Gen Antagonist
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I could see the throttle body maybe causing some shifting issues, but certainly not anything with the speedo, thats still purely electronic. The VSS sends a signal that tells it what to say, thats it.
 

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Discussion Starter #20
well, what chevy told my mother (shes the one that picked up the phone)...and this might sound like total BS. Is there is a switch in the throttle body that was shorting out, causing my RPM's to drop. I'm still not sure what having my steering wheel turning to the left had to do with that

but its not going to be ready, they can't find a f'n TB in stock, so they say it might be ready next week. Grrr
 
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