have a 99 s80 t6 that's been doing some strange things. i have a surge while driving . no particular rpm, no particular speed and it's intermitint. i've been threw the usual like vacume leaks, coil packs, injectors, fuel pressure ect. sometimes i get a message immediate engine service required but no check engine ligh or no code set. sometimes the immediate engine service lights while this is happening, sometimes it doesn't. when it happens it feels like someone is pulling on the e-brake when i'm driving. pulling and letting go. other than that the car runs awsome. plenty of power, revs fine ect.
here's another strange one. while in gear but at a stop, if i press the gas pedal while holding the brake nothing happens. it doesn't rev against the brake. it's like depressing the gas pedal while the engine is off. absolutely nothing all the way to the floor. it's completely dead. take my foot off the brake and it works as it should taking off with no hessitation at all. it did this the other day. i tried it today and while standing and applied the brake and the gas both. this time it reved against the brake. i'm sure somehow this is related to my ghost surge issue. they are two very strange issue's. i've also heard when i take my foot off the brake a hiss sound every once and a while driving. can someone explain how it's possible to apply the brake and the gas and have it act like the gas pedal is not even connected? thanks... holloween is approaching.. hmmm.