Help Needed... Dying upon start!
 

Hey guys, The past two days I have had a weird problem with my 02 Boxster S:

*************The second I start the car it idles high and then idles low, and then idles high again... then right back down low. It does this a few times and then just dies (engine shuts off). If I start it and let it go up high and down low it dies eventually, but if I hit the gas a bit before it dies it fixes the problem and the car idles fine and stay running. **************

If you think you can help me out then theres more info below (might be related or not).

The battery is new and fine so thats not an issue.

There are no CEL's coming on and all CEL light bulbs are working.

The air/oil seperator (or something like that) was replaced about 2 weeks ago. This was replaced after a few days of high/rough idleing and on the last day the car started shootin lots of smoke so I took it to the Porsche dealer right that second and they replaced the air/oil seperator... problem solved.

The 30k service was done about 6 months ago at the P-dealer (but they really didn't do much) but I'm letting you know of the 30k service because they likely did a check of the cars vital components and found nothing wrong, maybe they also read the engines computer, I don't know but thought it worth mention.

Then YESTERDAY for the first time I started the car and it had the weird jumpy idle I mentioned previously (up for a couple seconds, then down a couple seconds, then up... did this a few times upon start-up and then ran perfectly smooth. Then TODAY... I started the car, it had the same weird start-up, BUT this time died after a few seconds, etc like I stated above.

FYI- I desnork'd it and dropped in a K&N replacement filter (in the stock airbox) 2 days ago (the day before the problem started). But I have a pretty good feeling this has nothing to do with my problem, and is just a coincidence... I hope.

Anyone gots info for me? I looked online and found similar problems but nothing exactly the same from what I can tell. I was thinking maybe fuel filter replacement? MAF? Cats? Idle control valve (ICV)? Throttle body replacement/cleaning? Fuel pump? Fuel injection cleaning? This is a list of the likely culprits I found online. If anyone has a process of elimination/algorithm I could use to help me out that would be great, obviously I will eventually have to go to the dealer if the cheap/free things don't solve the problem. Also if there aren't any CEL's can the dealer still hook up something that reads problems with the engine?

I was thinking of replacing/cleaning/servicing etc a few of the things on that list if they are cheap or free since it would be good to do anyway.

Sounds like the MAF - related to your intake upgrade.

Unclip the electrical connector to the sensor and see if the car responds. If so, you found your problem.

I would start by cleaning the throttle body.

There may be oil on your MAF, who knows. Get a can of MAF cleaner from the parts store, take it out and try cleaning it before you frop 2 bills on a new one. I have had an aftermarket air intake & filter in my car for over a year now with zero problems. Probably just a coincidence, they seem to go bad whenever they feel like it.

I am 99% sure its not the MAF... the MAF wouldn't cause a problem quite like this... I think it would be shi*tty driving all around town, etc... and the shops I took the car to yesterday agreed. They are saying it's something in the fuel line which is obvious and I agree with that. It might be fuel pump, f-filter (doubtful), throttle body (likely). The performance shop that I have taken the car to a few times told me to have the dealer resynch or reprogram it? He said they have software and can program it or something along those lines. And he didn't mean just to unplug the battery which is what I thought he was trying to pawn off as a problem solver. So I am going to ask Porsche if there is such a program or tuning of the throttle body, etc. I have alot of knowledge in some areas and almost none in other areas and the throttle body is an unknown for me.

Oh and not to mention if the MAF was a prob I'm assume there would be a CEL. (there isn't)

sounds like a throttle positioning sensor to me. what did you find out?