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With moderate throttle pressure, my 850 feels like it can't decide to accelerate or not accelerate...<p>Sort of feels like the car is self modulating- pulsing the car to go faster. It's very subtle. <p>Any guesses?<p>Thanks,<p>Dave
 

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Re: Surging (xtremepsionic)

Well if it is a turbo, look at the turbo gauge. Doing what you mentioned on my turbo causes the boost pressure to be right on the line of actually adding effective boost and not, in other words between the black and white area. The needle will waver ever so slightly, and I can feel it in the drive. It may mean something is wrong, but I assume its just because you are getting boost pressure wavering in there between on and off. Its most noticable on hills were I must go 35 mph, the car seems to hit that area constantly.
 

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Re: Surging (pj's 850)

Could be a leak in the vacuum system too, check for leaks.<br><A HREF="http://www.volvospeed.com/bay13.htm" TARGET="_blank">http://www.volvospeed.com/bay13.htm</a><br>More imformation about the process can be found here.<p>Otherwise, dirty fuel system (throttle body, lines, fuel filter), worn distrbutor cap and rotor, or worn plugs. Might cause this.
 
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