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BOBBYSS
BOBBYSS, Master Technician
Category: Chevy
Satisfied Customers: 17142
Experience:  ASE MASTER CERTIFIED, AA DEGREE AUTO/DIESEL TECH
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Idles a little rough. Gas pedal response is fine after it

Customer Question

Idles a little rough. Gas pedal response is fine after it warms up a little. But in drive poor pedal response and shifts hard. Sometimes as high as five grand before it shifts
JA: Is the rough idle intermittent or consistent?
Customer: Intermittent
JA: What is the model/year of your Chevy?
Customer: 91 chevy silverado 1500 2we 4.3
JA: Are you fixing your Silverado 1500 yourself? What have you tried so far?
Customer: Pulled some codes and swapped map sensor and idle air control valve. Neighbor said it was catalytic converter, so he punched a hole in it. Then I got an O2 sensor code, so replaced cat converter and also O2 sensor. Still getting IACV fault code
JA: Anything else you want the mechanic to know before I connect you?
Customer: Is this gonna cost me anything?
Submitted: 1 month ago.
Category: Chevy
Expert:  BOBBYSS replied 1 month ago.

Hello, my name is***** you tell me how many miles are on the vehicle?

Customer: replied 1 month ago.
117,000
Expert:  BOBBYSS replied 1 month ago.

Thank you. It sounds like you have an issue with a vacuum leak. Most of the time this engine leaks vacuum at the intake manifold gasket. It can also be a failure in the MAP sensor. If the MAP sensor is not reading correctly then it will cause the computer to inject the wrong amount of fuel.

Customer: replied 1 month ago.
Will I get a map sensor code if it's the map sensor. I already swapped once already.
Customer: replied 1 month ago.
How about TBI gasket?
Expert:  BOBBYSS replied 1 month ago.

Some of the time you will get a MAP sensor code but not always. If the TBI gasket is leaking that can cause it also, but those do not leak too often.