About my car

Tiny
LIONELL8732
  • MEMBER
  • 1996 CHEVROLET MONTE CARLO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 217,000 MILES
This problem just started and I want to know what controls the rpm on my car because everytime I get up to speed my rpm would drop and I hear a weird sound and this only happen whenever I pick up speed
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Saturday, February 5th, 2011 AT 2:43 AM

29 Replies

Tiny
CARADIODOC
  • EXPERT
Once you're in third or fourth gear and the engine is warmed up, the torque converter locks up to increase fuel mileage. That will cause engine speed to drop noticeably. The converter will unlock if you tap the brake pedal. It will also unlock if you accelerate quickly. Sometimes a glitch in the throttle position sensor will trick the Engine Computer into thinking you're accelerating. That can cause the converter to unlock when it isn't really supposed. A misadjusted brake light switch can cause the converter to unlock intermittently, then relock a few seconds later.

Caradiodoc
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Saturday, February 5th, 2011 AT 5:21 AM
Tiny
LIONELL8732
  • MEMBER
So what should I have change so it would stop doing that
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Saturday, February 5th, 2011 AT 9:51 PM
Tiny
CARADIODOC
  • EXPERT
Brake light switch or throttle position sensor are the two most likely suspects that I mentioned previously. The problem is we hate just throwing random parts at a problem without doing any diagnosis first. That is the most expensive and least effective way to solve a problem, however, the most effective way involves connecting a scanner to the car, then taking it on a test drive. Most people don't have access to a scanner so we have to resort to just trying new parts.

One simple thing you can try is holding the brake pedal up with your foot when the problem occurs. If that makes the problem stop, try readjusting the brake light switch. If the problem occurs more often at one specific speed or when you move the gas pedal just a little, suspect the throttle position sensor.

Some shops have a scanner that they can connect to your car that has a record / playback feature. You press the record button as soon as the problem occurs. Because the data travels through the scanner's memory, the recording actually begins a few seconds before you pressed the button. Later, the data can be replayed while watching for what caused the torque converter to unlock.

Of course, this all assumes that's what's happening. There really shouldn't be any noise associated with the converter unlocking unless the converter is what's causing the problem. A transmission specialist might be able to tell that on a test drive.

Another way to find the source of a noise is by using a tool called a "Chassis Ear". That is a set of six microphones, a receiver, and a set of head phones. Many mechanics have never heard of or seen this tool. You clip the microphones to suspect points under the car, then switch between them while listening with the head phones on a test drive. Moving the microphones around lets you zero in on the source of the noise. The tool costs $200.00 from Mac Tools. I can post a link to their web page that shows what it looks like if you need it. It's available from the other tool truck guys too like Matco, Cornwell, and Snapon.

Caradiodoc
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Saturday, February 5th, 2011 AT 10:26 PM
Tiny
LIONELL8732
  • MEMBER
Ok so everytime I switch gears I hear a zoom noise exspecially when im going over 60 mph on the highway and I have to get off quick becasue of what it might do.
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Saturday, February 5th, 2011 AT 11:43 PM
Tiny
CARADIODOC
  • EXPERT
That sounds a lot more significant than just an unlocking torque converter. There could be slippage taking place in the transmission's clutch packs. You would hear the engine pick up speed during shifts. This would be a good time to visit a transmission specialty shop. Typically they will test drive the car with you riding along. They should be able to provide a better diagnosis based on their observations.

Caradiodoc
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Sunday, February 6th, 2011 AT 1:46 AM
Tiny
LIONELL8732
  • MEMBER
Do you no where my DPFE sensor is located at on my car because there is nothing wrong with the tranny, my cel lgiht is on and I got a code of P0401 and thats what I feel is the problems with my car and why its acting like this. I just change the egr valve and I feel the sensor's are bad.
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Sunday, February 6th, 2011 AT 10:07 PM
Tiny
CARADIODOC
  • EXPERT
DPFE sensor is a Ford item. No other manufacturer uses that.

You were talking about a noise at higher speeds. You're going to have to get someone to test drive your car so they can figure out what that noise is.

Caradiodoc
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Sunday, February 6th, 2011 AT 10:32 PM
Tiny
LIONELL8732
  • MEMBER
I have a P0401 code that is on now and I just change the egr valve which is brand new. Whatever is code is my car is doing and this is the only code that is on as well
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Sunday, February 6th, 2011 AT 10:38 PM
Tiny
CARADIODOC
  • EXPERT
You can try changing the EGR sensor but it might just be reporting a problem to the Engine Computer. During a self-test while driving, there might not be enough exhaust gas flow. One possible cause is a passageway under the EGR valve clogged from carbon buildup.

Caradiodoc
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Sunday, February 6th, 2011 AT 10:57 PM
Tiny
LIONELL8732
  • MEMBER
What kind of sensor's should I change because it gets worst when I drive up hills thats when gas is not be applied somewhere.
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Sunday, February 6th, 2011 AT 11:32 PM
Tiny
CARADIODOC
  • EXPERT
I don't think you have a sensor problem. You need a professional diagnosis so you don't waste your time and money on the wrong parts.

Caradiodoc
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Sunday, February 6th, 2011 AT 11:49 PM
Tiny
LIONELL8732
  • MEMBER
Ok thanks
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Monday, February 7th, 2011 AT 12:02 AM
Tiny
LIONELL8732
  • MEMBER
I have a code P0410 and I want to no what it is and what should I change my car is running bad from this code
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Friday, February 11th, 2011 AT 11:15 PM
Tiny
CARADIODOC
  • EXPERT
Codes don't indicate specific parts. They point to the circuit or system with the problem that needs diagnosis. I don't have a listing for that specific code, but 400 codes pertain to the emissions system. The lower codes are EGR-related. Suspects are the valve, the sensor, or the passages could be blocked with carbon.

Caradiodoc
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Saturday, February 12th, 2011 AT 1:05 AM
Tiny
LIONELL8732
  • MEMBER
Where is the smog pump located at on my car if you know and I change the egr valve which is brand new and I had my throttle body clean out really good so I no thats not clogged up anymore as well.
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Sunday, February 13th, 2011 AT 2:27 AM
Tiny
CARADIODOC
  • EXPERT
Smog pump, if one is used, is driven by a small belt on the front of the engine.
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Sunday, February 13th, 2011 AT 2:37 AM
Tiny
LIONELL8732
  • MEMBER
It was the smog pump and I change that but I'm still getting a code of P0306 and I change the spak plugs, wires, all three coil packs and the catalytic converter as well and they are all brand new parts so what should I change now.
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Thursday, February 17th, 2011 AT 2:37 AM
Tiny
CARADIODOC
  • EXPERT
Why do you insist on changing stuff? That is by far the most expensive and least effective method to diagnosing a problem. You might not even have a defective part. There could be a corroded terminal in an electrical connector, a cracked vacuum hose, a leaking intake manifold gasket, carbon plugging an idle air passage. Etc.

You need to approach this like a doctor approaches an illness. They don't do a heart transplant then watch to see if that fixed the problem. They perform all kinds of tests first to rule things out and narrow down the list of possibilities. We aren't even sure yet what kind of noise you're hearing. That not only makes a diagnosis over a computer impossible, there's no way to make observations or perform quick tests. The codes you're getting could even be caused by nothing more than disconnecting things while the ignition switch was turned on. You might try disconnecting the battery for a few minutes to erase the codes, then see if they come back. If they don't, you may have been on a wild goose chase looking for a problem that doesn't exist.

Caradiodoc
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Thursday, February 17th, 2011 AT 3:25 AM
Tiny
LIONELL8732
  • MEMBER
The reason why I'm changing everything is because the person who I bought the car from swore that they had a premium tune done on the car before I bought it and that's wasn't right so thats when the P0306 code started poping up so I decide to change things but there is sumthing else I didn't do because the code is still poping
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Thursday, February 17th, 2011 AT 4:19 AM
Tiny
CARADIODOC
  • EXPERT
Yup, I understand, but you want to solve this problem the best way possible and I don't think that is going to happen without having a professional who can stick his head under the hood. This isn't a simple or common problem.
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Thursday, February 17th, 2011 AT 5:15 AM

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