Injector Tuning a rough idle?

Tiny
NOTALATTE
  • MEMBER
  • 2014 CADILLAC CTS
  • 3.6L
  • 6 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
Hello. I recently replaced a faulty injector on my 14' Cadillac CTS Vsport 3.6TT (similar to the LFX). After installation, I still retain a rough idle. My question is if this injector needs to be programmed to the ECU?
Saturday, January 3rd, 2026 AT 11:14 PM

7 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,387 POSTS
No programming needed for an injector. How did you determine the injector was the problem? Did you use an OEM injector?
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Sunday, January 4th, 2026 AT 7:03 AM
Tiny
NOTALATTE
  • MEMBER
  • 4 POSTS
Used ACdelco. I swapped the injector to another cylinder and the misfire followed it. Replacing did fortunately eliminate multiple misfire instances. However I still have a rough idle. I read up that some newer vehicles require new Injectors be programmed to the ecu and that's where that he question came from.
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Sunday, January 4th, 2026 AT 11:49 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,387 POSTS
Nothing in them to program. However you might want to read this service bulletin. https://static.nhtsa.gov/odi/tsbs/2019/MC-10158838-9999.pdf
It talks about a rough idle that may be normal.
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+1
Sunday, January 4th, 2026 AT 7:08 PM
Tiny
NOTALATTE
  • MEMBER
  • 4 POSTS
Appreciate the insight!
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Monday, January 5th, 2026 AT 12:05 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,387 POSTS
Just for of the fun that is a GDI engine and it's oddities. One thing that can cause unstable idle that doesn't get talked about is the need to manually clean the valve deposits off the intake valves. Not really a DIY job as the tools get pricey but it is something that might not be well known.
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Monday, January 5th, 2026 AT 3:16 PM
Tiny
NOTALATTE
  • MEMBER
  • 4 POSTS
Yeah, I did the I take valves as well as they were caked with carbon. Maybe the other 5 injectors need replacing as well to clean the idle up.
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Monday, January 5th, 2026 AT 4:18 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,387 POSTS
As the bulletin says, the rough idle may be normal if it does it during the times the system is testing the pump. Hard to tell unless you are watching the live data with a scan tool to determine if that is the case or if it's due to something else.
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Tuesday, January 6th, 2026 AT 12:13 AM

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