Hi there, I have a 2006 Buick LaCrosse that fluctuates in RPM. The reason I'm posting this is because my situation seems a bit different than the threads that seemed to have a similar problem.
The surging occurs when I'm accelerating slowly, right around the 2000 RPM range. Here, it will bounce +/- 400 RPM repeatedly until I enter 1. let off the accelerator or 2. apply more pressure to the accelerator.

The issue seemed to begin after I replaced my air filter. I thought it might've just been that I installed in incorrectly, but after checking a million times, I can confirm that both the air filter was the right size, and that it'* installed properly.
Since then, I tried replacing the throttle body with a junk yard unit, but that didn't fix the problem. I took it to a shop, and they tried replacing the spark plugs and wires, and while this seemed to slightly help the issue, it never went away.
The only time the issue seems to go away is if the car'* battery has been disconnected for over 20 minutes. I discovered this when I had to replace the battery, and it seemingly stopped. Well, over a month later, the exact issue returned. It seems that I can always get rid of the issue by disconnecting the battery, but it always ends up coming back.
Just yesterday, I tried cleaning my MAF sensor and cleaning my battery terminals, as people also said that these things can cause it. However, I'm wondering if there'* anything else I should try? I've heard the issue with the TCC Solenoid, but the surging still occurs while holding the brake down, so I don't think that'* the issue.

Does anyone know what else may be causing this? All help is appreciated.

Link to related threads:
https://www.gmforum.com/buick-172/06...ps-lil-296277/
https://www.gmforum.com/buick-172/05...-311835/page2/

That air cleaner box is going to be all worn out now.

I'm scared of this shop. Glad they only got you for plugs and wires.

This probably "works" because it forgets its presets and has to "learn" itself again. During the process it is a little more conservative than otherwise.

​​​​​​​Personally . . . I'd check fuel pressure next. need to see what it is doing. Since you're not mentioning hard slamming, I suspect the issue is fuel and not electrical.
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​​​​​​​Unlikely it is this since they are deviating 100RPM each way and you are deviating 400RPM each way.

Awwwww . . . I remember this thread. It was so long ago! Too bad Devildog never came back so we could see it through!

How many miles on the car?

How many miles have you owned it?

​​​​​​​Any trauma or major repairs that you know of?


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[QUOTE=CathedralCub;1649014]That air cleaner box is going to be all worn out now.



I'm scared of this shop. Glad they only got you for plugs and wires.



This probably "works" because it forgets its presets and has to "learn" itself again. During the process it is a little more conservative than otherwise.



Personally . . . I'd check fuel pressure next. need to see what it is doing. Since you're not mentioning hard slamming, I suspect the issue is fuel and not electrical.

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Unlikely it is this since they are deviating 100RPM each way and you are deviating 400RPM each way.



Awwwww . . . I remember this thread. It was so long ago! Too bad Devildog never came back so we could see it through!

How many miles on the car?

How many miles have you owned it?

​​​​​​​Any trauma or major repairs that you know of?


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I would agree with this, but usually it does only bounce about 100-200RPM. Honestly, I'd say that'* what it does most of the time. However, there have been a few occasions where my car bounces like crazy, and that'* typically when it'* 400RPM.

I only know the very basics of how to test fuel pressure. Is there any specific way you'd suggest I'd do it on the 3.8L? Or should I just go with a general guide?

The car has 165,000 miles on it. I bought it at 108,000 miles about 3 years ago, and the surging started about a year and a half ago, which was roughly 130-140k miles.
Outside of needing new fuel lines (that was after the bouncing started), there have been no major repairs that would've been related to the fuel, air or electrical system.

I greatly appreciate the response, sorry for the late reply.

Do you have a scan tool? I'd be looking at a couple PID'* and see what'* going on. Sounds like it'* easy to make happen.

You're going to need a fuel pressure gauge, and connect it to the test port on the fuel rail.

If you haven't done this before, you might want to Youtube it, and maybe pick up a Haynes or Chilton'* manual for your car.

Service manual.

I can access one quite easily. What types of things should I be looking for? I forget if I mentioned it previously, but there are no lights on and there are no codes when I plug one in,

'The surging occurs when I'm accelerating slowly, right around the 2000 RPM range. Here, it will bounce +/- 400 RPM repeatedly until I enter 1.'

What gear are you accelerating in before you ENTER (strange terminology) 1?

Ooooh I missed that. Good question!

[/QUOTE]What gear are you accelerating in before you ENTER (strange terminology) 1?[/QUOTE]
Sorry, it was a typo in the original post. It was supposed to say "either 1. 1. let off the accelerator or 2. apply more pressure to the accelerator."
Regardless, it seems to happen in every gear. The primary gear that it occurs in is the 3rd gear, but I've caught it in 2nd gear when going 30-40 MPH as well.