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Discussion Starter · #1 ·
Last month I thought I had a "power modulation" problem and took the car into the dealer (R Salesman's) and they did find a trouble code and fixed/cleared it with a software update. However, I have noticed that the problem persists to a smaller degree. So I'm wondering if anyone else here has experienced this in their car.

Description:
Under steady throttle but accelerating, about 2 seconds after shifting, the throttle appears to oscillate. How noticable it is depends on throttle load. If I'm under light load (but always steady throttle pressure) it is barely noticable, but under heavy load, say 80%-95% throttle, about 2 seconds after shifting the power drops, increases, drops, increases, drops, increases, as if you were pumping the throttle 2-3 times per second.

Sounds familiar to anyone?

I don't know how I can better describe this to the service writer. Last trip in he said if there was no trouble code in the computer, there was nothing they could do (what DID they do before computers?) Maybe I should have Lee drive it. I'm sure as an R owner and former tech he would immediately see this is not normal. It sure didn't happen the first 15 months I had it.
 

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Re: Throttle oscillation? (vLGrok)

I actually think it's a programming issue inherent in the stock ECU code. It's very subtle . . . a slight "burp" in acceleration around 3 to 4k rpm. I've only noticed it on stock R's under moderate to heavy acceleration when the engine's still cold. I certainly don't mind taking your vehicle out for a spin to see if it's more pronounced than what I've seen in other vehicles.

Look on the bright side: prior to computers, you couldn't get 30 more hp for something as simple as a ~$1000 ECU upgrade. Nor could you get as good fuel economy at similar horsepower levels.
 

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Re: Throttle oscillation? (vLGrok)

I know EXACTLY what you are referring to.

I had this issue on my S80 but only under full throttle between 80-100. It was ultimately corrected by an ECU update but only after several dealer visits and finally a diagnosis/test drive with the Regional Volvo Rep.

Thankfully, I have never experienced this with my R
 

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Re: Throttle oscillation? (vLGrok)

Most 5 cyl Volvos seem to do this (stock) I think the ECU is programmed very LEAN
A nice ECU upgrade will completely cure this
 

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Re: (daves60r)

Quote, originally posted by daves60r »
it might be the boost control soloid!!
No it's not. What about they ALL seem to do this, don't you understand?
It's in the Volvo ECU programming, very lean running. Lean can cause light surging
 
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