Ceissus

iTrader: (4)

Ok. here is the scenario:

cold start....my car runs/idles like a dream. Same thing all the way to closed loop when it gets nice and hot.

The problem is when i turn my car off, and come back to it shortly thereafter.

If it sits for anywhere from 5-35 minutes, when i start it back up, it will burp and sputter like it's running on 4 cylinders. This continues until it gets nice and hot again and back into closed loop(anywhere from 5-10 minutes). ONLY then does it clear up and run smoothly again.

Note: when it's doing this misfiring stuff, it's mainly at low RPM's. If i baby it up to about 2500 or above it will clear up a good bit but still runs terribly until it's hot.

What the heck is causing this? Does it sound like a tuning issue? maybe a PCV issue?

I havn't done anything to trigger this and i just started to notice the problem about a month ago after i fiddled with the vacuum lines at the rear of the manifold.

Any input is appreciated!

txh0tb0i972

iTrader: (63)

im not sure if this is the problem.... but try an o2 ..... the way i checked them is unplugged 1 by 1 ..... try that...... unplug 1 and if it still does it plug it up and try another one....never hurts to try a harmless deal

Ceissus

iTrader: (4)

one O2 sensor is brand new and the other is......questionable.

It didn't seem as active as the new one when i scanned it. Maybe its not heating up properly anymore?

ls1nightrider

iTrader: (4)

Yep try checkin the o2 sensors also mine would do that if i put cheap 87 gas..always use the good stuff

1320FEVER

iTrader: (9)

The only thing I can think of is you may have a vacuum leak from when you messin' with the vacuum lines. I'm not sure but maybe in open loop your pcm is working off your VE tables which will no longer be valid since you have a vacuum leak, and hence, making your engine run like poo. Then, when you enter closed loop your fuel trims kick in and gives the engine what it likes/needs and it no longer needs the VE tables. Bottom line is I would try and find the vacuum hose you were messin' with and see if its loose or something and fix it.

ex-SS-ve

iTrader: (9)

could also be the cyl head temp sensor. if that goes bad itll throw off the fuel tables and the timing pretty bad. just a guess. but ide scan that thing to be sure.

pSSycotic

iTrader: (7)

mine was doing the exact same thing, but it would do it on cold starts too. the 02s were showing problems. It started after i went though kinda high water on the freeway. did it for about 3 or 4 days then went away. WHen i would drive it to the shop to get it checked out it would of already heated up enough it wasnt throwing codes...give it a few days and see if it clears itself up. i found that the longer it sat off, the longer the studdering would stay

Ceissus

iTrader: (4)

Thanks fellas. Gonna try all of the above suggestions~