When the engine is cold it idles extremely rough?

JAVIER PEREZ4

MEMBER
2001 CHEVROLET SUBURBAN
5.3L
V8
2WD
AUTOMATIC
230,000 MILES

Whenever I start my vehicle listed above 1500, when the engine is cold it idles so rough to the point where I have to step on the gas for it to stay alive. Once it has warmed up for a bit it idles around 500 RPMs.

I don’t know much about trucks but I'm not sure what it is also whenever it’s warmed up there's times when I'm driving and it randomly loses acceleration like I'm full throttle, and it barely revs up past 2,000 RPMs and when it does it barely moves. When the MAF sensor is unplugged, it seems to work okay. But we already got a new MAF sensor. So, I've been told it’s the coil packs but I'm not sure what it could be.

We also recently switched out the EGR and it is still the same.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
45,785 POSTS

I would start with a tune up with coils and spark plugs and I would service the throttle bore and IAC valve. Here are guides to help us rule these things out, also can I ask if the check engine light is on? If so we should run the codes to help point us in the right direction.

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

and

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

And this video to show you step by step on how to service the throttle bore:

https://youtu.be/Z3LDHdS1upo?si=dN6oiJTnUJ4IcYxI

I would replace the spark plug wires as well.

Spark Plug Type .................... Denso: PTJ16R15

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Tuesday, September 3rd, 2024 AT 3:55 PM

JAVIER PEREZ4

MEMBER
2 POSTS

Yes, if we were going to replace the coil packs, we were also going to replace all the spark plugs the last time we had gotten a misfire code but I'm not sure for what cylinder. But yes, we’ll also try to get a good cleaning of the throttle body we had also gotten the throttle control valve replaced as well as the idle air control valve like less then 2-3 months ago.

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Tuesday, September 3rd, 2024 AT 4:01 PM

KEN L

MASTER CERTIFIED MECHANIC
45,785 POSTS

Is the check engine light on? If so, we should run the codes, also how does it sound when cranking over, can you upload a short video of what's going on so I can see?

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Wednesday, September 4th, 2024 AT 9:58 AM