Codes PO102, 122, and135, idles high and bogs down at 30 MPH

Tiny
JBRONJR1
  • MEMBER
  • 2000 BUICK LESABRE
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
It's been running really dodgy. Would stall at stops intermittently. I replaced the post cat o2 sensor and the MAF. It ran way better, but still not up to par. Today I removed the air intake system. Blew out the air filter even though it's still white. I took off the throttle body and cleaned it pristine. It was really gummy and sticky. I cleaned the IAC valve. It was gummy as well. Cleaned the intake air temperature sensor with MAF cleaner. Got it all back together. Starts right up. But it's now running at about 1,500 RPMs and won't drop down. I drive it and when I get to about 30 MPH it bogs down. It's not shifting into second. Almost like a safety something. Do I need to disconnect the battery for a reset? Is it possible that I inserted the idle valve incorrectly? I can manually grab the throttle cable at the body and make it idle down, but soon as I let it go it idles back up. I don't see any kinks or bends in the throttle cable either, it's routed just like it was when I took it off.

I put my code reader on it, it showed PO102, 122 and135 freeze frame. Then the same three codes pending. I erased and got 122 pending. Started it and it ran at 700 RPMs. Tried to drive and it went back to 1,200 RPMs and wouldn't shift to second and the RPMs were erratic. Erased again. Started again. I'm left with PO122 on freeze and pending and 102 pending.
Friday, July 8th, 2022 AT 5:04 PM

5 Replies

Tiny
JBRONJR1
  • MEMBER
  • 4 POSTS
I unplugged the MAF, got 900 RPMs at idle. I drove it and it still won't shift into second. Funky RPMs as well. Plugged that back in, unplugged the idle valve and got 1,800 RPMs at idle. Maybe I did something wrong with installing the idle valve?
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Friday, July 8th, 2022 AT 5:48 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

The P0122 is related to the throttle position sensor. There is a voltage variation that is outside the manufacturer's specifications.

Do me a favor. I believe you have a scanner. If so and it has live data, you should be able to perform the diagnostics for the code. I suspect the issue with the TPS is causing the idle and shifting issues.

Let me know if you feel comfortable performing the tests.

Take care,

Joe

See pics below.
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Friday, July 8th, 2022 AT 10:30 PM
Tiny
JBRONJR1
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I forgot to mention that I removed the TPS as well. Is it possible that I installed it incorrectly? (That's what I meant to ask instead of asking if I installed the idle valve incorrectly)

Sorry about that.
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Saturday, July 9th, 2022 AT 9:26 AM
Tiny
JBRONJR1
  • MEMBER
  • 4 POSTS
That was the problem. I watched a little one-minute video on YouTube, haha. You have to canter it to the right, then turn it left to align the bolt holes. It runs like a dream now.

Thank you very much for your time and effort I truly appreciate it.
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Saturday, July 9th, 2022 AT 10:43 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

You are very welcome. I'm glad to hear you got it fixed. They can drive people crazy if we let them. LOL

Regardless, take care of yourself, and please feel free to come back anytime in the future.

Joe
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Saturday, July 9th, 2022 AT 10:46 PM

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