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Won't rev past 3500. It runs fine at start up but when it…

Won't rev past 3500...

Won't rev past 3500. It runs fine at start up but when it warms up,no power won't revue past 3500 rpm

Mechanic's Assistant: Is the power loss consistent, or does it fluctuate?

It fluctuates up to about 4000 and back to 3500 at full throttle

Mechanic's Assistant: What year is your 4000?

2004 huyndia sonata

Mechanic's Assistant: Are you fixing your 4000 yourself? What have you tried so far?

TPS anaMAFS

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Took it to shop they told me it was cats clogged up

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Answered in 16 minutes by:
11/16/2017
Tim Mohr
Tim Mohr, ASE MASTER
Category: Hyundai
Satisfied Customers: 16,621
Experience: 30 YEARS EXPERIENCE, FORIEGN AND DOMESTIC, GAS AND DIESEL
Verified

Hi, my name is ***** ***** it runs good cold, but powers out when warm, then this is caused y a partially plugged cat converter, it can easily be verified by a exhaust backpressure test, was this test done?

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Customer reply replied 8 months ago
Not sure. It's a good shop I've used many times. I had removed the pipe from the header before taking it in, with no change. He told me the cat are made into the headers so that would not have made a difference.

no that wont make a difference, you need to remove the front o2 sensor and screw in a low pressure gauge, and start it, if the pressure is any more than 1 psi, the cats are plugged,Tim

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Customer reply replied 8 months ago
I'll try that. Could it be a knock sensor?

No, a knock sensor will not do this, the metal in the cat converter expands when it gets hot, and blocks the flow of exhaust, then contracts as it cools, so this is going to be a bad cat converter,Tim

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Customer reply replied 8 months ago
Cool thanks for the help. I'm going to work it now. Wish me luck.

Anytime my friend, please dont forget to rate me, so I can get credit for helping, thanks,Tim

Tim Mohr
Tim Mohr, ASE MASTER
Category: Hyundai
Satisfied Customers: 16,621
Experience: 30 YEARS EXPERIENCE, FORIEGN AND DOMESTIC, GAS AND DIESEL
Verified
Tim Mohr and 87 other Hyundai Specialists are ready to help you
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Customer reply replied 8 months ago
I just gutted the cats and same problem. Runs great until it warms up. What do I try next.
Customer reply replied 8 months ago
I did as told but the problem persists. What do I try next?
David Craig
David Craig, Auto Mechanic
Category: Hyundai
Satisfied Customers: 5,808
Experience: Owner/Mechanic at 3D Automotive
Verified

you need to contact the original Tech since he has already been paid for the answer

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did you run a backpressure test on this, before gutting the cats??

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Customer reply replied 8 months ago
No,I do not have a pressure tester. So I removed the headers and o2 sensors and cleaned out cat material. Then replaced everything. Also removed check engine light from dash. This car has almost 300000 miles on it. I have replaced most of the suspension and top side of motor. Over all the car is in great shape and my wife loves it,so I need to fix this issue and life will be good. it runs great till it heats. When this started it was very intermittent. Would go great for days then suddenly go into limp mode. Now it happens a few minutes into driving it.

have you had the codes read from the computer?

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