2001 S40 2.0T Auto - Refusing to idle & struggles to start

[VanBessinger]

First off, I'd just like to say I'm a complete noob when it comes to this vehicle, so any advice given would be much more appreciated if a link to a 'how-to' guide or similar could be posted along with it. I have downloaded and installed VADIS in an attempt to self diagnose the problem, but it's not working as advertised on my system, so I've had to resort to the forum in the hope of finding a solution.

I bought a secondhand S40 2.0T with automatic transmission about 6 months ago. Car's in good shape overall, clean engine, no oil leaks, stock standard with no mods or anything. Mileage is around 130k and she doesn't use any oil, no stuttering, no major issues. Only thing I picked up after purchasing is that she starts much easier when she's stood overnight than, say, after an hour of standing in the sun in the parking lot. Over the last month or so the hot weather starts have gotten worse, the engine cranking and struggling to start initially, and then sending out a small puff of black smoke once she takes, idling rough for about 15 seconds or so and then evening out.

Two days ago I dropped off some goodies, literally ran in for 5 minutes, came back out, cranked her, crank, crank, crank, no dice. I put a bit of foot on the accelerator pedal and she started, but as soon as I release the pressure the idles would drop fairly rapidly all the way down to zero, she would stutter and die, with me of course losing all my marbles in the process. One I figured out that I need to keep my foot on the juice I drove her home, one foot on the juice, and one foot on the brake, nearly taking out a couple of folks because I'm used to using my left foot for the clutch pedal when driving stick.

Anyway, got her home, dug around the interwebs for a possible problem/solution scenario with little luck. Eventually opened up the engine bay and adjusted/tightened the idle cable to make sure she doesn't die on me. Now she idles a bit high, about 1300rpm, and then as soon as I put her into drive she drops down to about half that, with me sometimes having to catch the accelerator to keep her from dying.

I'm not scared of getting my mits dirty to fix this, just completely clueless as to where to begin looking for the problem as all the previous cars I owned were a whole lot less complicated than this one, so it's hard to know where to start without breaking something. She drives fine once we're going, it's just when cold and standing still she wants to die on me. I've also noticed that fuel consumption has gone up a bit as I drive a fair distance to work and back on a daily basis.

Any advice/pointers/suggestions with as much detail as possible would be highly appreciated. Thank you in advance. Oh, and apologies for the long-winded post. Peace.

[Livens]

Any CEL's?

A few things I would check first. Pull the plugs and make sure they look normal and are gapped properly, ~0.03" I believe. Also check your air filter.

It could be your coils. When mine went bad they would run fine when the engine was cold, but once hot, especially sitting in traffic, the engine would start missing and want to die unless I help the gas on a bit. Cylinders 3 and 4 have coils over the plugs, with a wire running from 3 to 2 and from 4 to 1. Unplug the coil and undo the 10mm bolt to the right of the coil. Not much you can do to check them, but both of my coils had a fine crack in the plastic post that runs down to the plug. That crack would get bigger when hot and the spark would ground out to the head. This was at 135k on a 2003 S40. I tried wrapping the posts in electrical tape and that helped a bit but she still ran rough when it got too hot.

Also you could clean your throttle body. I had a ford that would get grime built up around the resting position of the throttle plate. At idle the car would die but once you hit the gas, even a tiny bit, everything was normal. The plate had a small gap all the way around it to let a small amout of air through at idle. If that gap gets clogged up the car will not idle propery. Easy to check and easy to clean. Just stick you fingers up in their with the throttle plate wide open and feel for a ridge of something where the throttle plate sits when closed. I doubt this is your problem, but its an easy free check to do.