Shudders and misses while cruising

ALLAYNA WRIGHT

MEMBER
1999 CHEVROLET TAHOE
5.7L
V8
4WD
225,000 MILES

Okay, at first it only did it about once a month. Now it does it all the time. While giving it a little gas and keeping it under load it does fine but when I just cruise it shudders and misses. The motor hardly makes a noise been well taken care of. Where should I start it was my father's and I refuse to ditch the motor. Changing plugs today.

5 Replies

DANNY L

MECHANIC
5,648 POSTS

Hello, I'm Danny.

My first question for you is the check engine light on? If you don't have access to a scanner/code reader most auto parts stores have a tool loaner program and will rent you one. Here is a tutorial showing how to check for check engine computer/diagnostic codes:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Once you perform this you can get back to us with any code(s) and it will help us better diagnose this sputter problem you're having.Hope this helps and thanks for using 2CarPros.

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Friday, March 27th, 2020 AT 2:09 PM

ALLAYNA WRIGHT

MEMBER
3 POSTS

I had the battery unplugged long enough that it erased the codes. Check engine light hasn't came back on. Yet!But last time I had it checked it said it was the catalytic converter or o2 sensor. Just changed my fuel filter and plugs and wires. Seems sluggish and misses less but still not better can a catalytic converter or sensor really make it shudder?

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Friday, March 27th, 2020 AT 3:01 PM

DANNY L

MECHANIC
5,648 POSTS

Hello again.

Actually yes, It can. Especially if a catalytic converter is plugged. If/when the check engine light comes back on if you save the code number I can tell you specifically which one is suspect. Your truck has 2 and I've attached a picture below and circled in red. Hope this helps and thanks again for using 2CarPros.

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Friday, March 27th, 2020 AT 5:08 PM

ALLAYNA WRIGHT

MEMBER
3 POSTS

Okay, the codes are p0430 catalyst efficiency below threshold (bank 2). Could it be wiring harness sensor or do I need new catalytic converters?

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Saturday, March 28th, 2020 AT 8:08 AM

DANNY L

MECHANIC
5,648 POSTS

Hello again.

I would just suggest the bank 2 left (passenger) side catalytic converter. Mine went out at about the same mileage you have. Here in California I paid $269.00 installed at my local shop. If you are not in California they can be a lot cheaper for just a universal replacement. Attached a picture below and circled in red which one it is. Hope this helps and thanks again for using 2CarPros.

Danny-

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