My '98 v70 is coming up in 190k miles and it just started having ignition problems. When the problems started, it would only be on extremely hot days when the car sat for > 8 hours in the heat. I would go to start the car and on the first try, it would turn over for awhile but no start, so i would take out the key and on the second attempt it started completely normally. However, the problem has progressed to where on even mild temperature days, and letting it sit for over only 3 hours, i will go to start it the first time and it will turn over for awhile but no start. The difference is now (aside from the temperature and time changes) that the second time i go to start it it will eventually start but as soon as it does it immediately sounds like it's going to sputter out and the rpms plunge close to 0 until half a second or two later the rpms will shoot up higher that usual and then settle back down to normal (i never apply pressure to the gas pedal). Once started, the car runs fine and there has been no loss in power, acceleration, ect... My local mechanic says it's just an age problem (i've driven cars with 300k miles that dont have any trouble like this) but i want to know what the problem actually is... Any suggestions?

 

Without testing things it's hard to guess. My first guess is that the fuel pessure is low. How old is the fuel filter? How about the fuel pump?

MY next guess would be that the fuel pressure regulator is goiing out. Sometimes they seep the pressure down and they pump has to build pressure back up efore starting. What you can try is, turn the key on and wait 5 seconds before you turn the starter on. See how that turns out.

Then you can check fuel pressure. If the pump is going out, it may not be supplying enough pressure.