HELP...my car will not idle (first issue with car)

Ok so my car sat in the garage for a little over a week from the last time I drove it. I had no problems when I drove it then. But now I go out and start it, yes it starts, but it will not idle at all. It is acting like it is mis-firing, very rough idle. If I do not touch the gas it will die. If I give it some gas the rpm's go up and the 'roughness' goes away. But then after letting of the gas it idles rough again and dies. Not sure where to begin to look. So I am reaching out to my Rennlist buddies to see if you have an idea as to what is going on and what I need to do next? I do not want to take it to a shop if not needed.

What does the code reader tell you?

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Doug, the code reader is on my list to get although I am not sure what model to get. Would there be any lights on my dash when this is happening like a CEL or something?

Steven, check to see if you have a loose vacuum hose. This can cause the car not to idle or to idle very roughly.

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Any code reader is better than none at all, but it would be nice to have something that displays live data. Or, if you only do diagnostics on your 996, get the Durametric stuff. You can have codes without having a CEL. If a quick look doesn't show anything obvious (connector dislodged, vacuum line or intake plumbing issue, etc.), the code reader is the next step. IIRC, you recently had the throttle body off for cleaning. Anything you touched while doing that would be a good place to start.

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Well I used the light in the engine compartment and a torch (flashlight) and looked around and everything looks OK but then of course I am not sure what vacuum lines are where.

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Yep I looked around the throttle body but did not see anything. Plus that was a little while ago now that I had it off and I have driven it several times since then with no issues. I would like to get a schematic of vacuum lines for my car so I can check everyone of them. Since I do not have access to a code reader currently and would like to diagnose the problem ASAP since it is starting to worry me, any advice at this moment in trying to figure out why the car ran good one minute and now it does not, is greatly appreciated. If you can tell in my tone of the messages I am a little concerned here since I don't understand why this would happen, plus it has been a very bad week for me in all areas of my life and this is not helping. I was planning on taking a nice drive in the car to take my mind of things but not now.

Could be a couple various things. Here's some to consider: 1. MAF sensor bad? Try cleaning it with some brake cleaner. 2. Vacuum lines? 3. How's the mileage on the car? Spark plugs? 4. Go pick up a bottle of Techron (good to do at every oil change) to clean the injectors. Most Auto Parts stores have an OBDII code reader. See if you can get it checked out. My bet - the MAF. Classic symptom is very rough idle.

Since the car has been sitting for a week, fuel contamination (finally settling in the tank) might also be a cause. Did you add fuel to the tank during your last drive? Any vacuum leak - oil filler tube, loose hose clamps on any of the intake plumbing, anything that would leak air into the intake without metering it through the MAF - should be considered.

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+1 On everything. Start from what costs less to most. C.

SD In my days of V8 I would spray (carb cleaner & a another product???) on the carb to see if the rpm would change...If it did not change than it had no vacuum leaks, Not a heavy spry, but a fast mist and have somebody hold the rpm constant Have you tried to run the car and see if it would just clean itself up?

Thanks Doug and Chad. So if the gas is bad what can I do to solve that? I cannot remember if I added fuel to it either the last time I drove it. I am about to have dinner and may look at it afterwards but I doubt it, too cold and dark in the garage now. I will keep you posted. Anything else you can think of please let me know. Thanks

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Unfortunately it dies before I can get around to the back of the car to grab the accelerator to keep it running.

I'm not sure if you got Chad's meaning- but most autoparts stores will let you borrow the OBD reader without buying it (or pay a small fee)

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There is a product that help evaporate water if present in the tank. I cannot remember what the name is. Also - go get some fresh fuel and add it to the tank (if possible). And yes...thank you dresler, that is what I meant. AutoZone has them and so does Pep Boys. Good luck. C.

Steven, Have you replaced the air filter recently? I cleaned out my evo airfilter and did not reoil a while ago. It ran rough and had a rough idle. I ended up burning through a MAF and reoiling carefully by letting it sit overnight before installing. I would also check for any air leaks from MAF sensor to the throttle body for additional air leaks. Are the clamps tight on the hose and is it fastened on securly? I have found our porsches very sensitive in that regard or you may have a bad MAF. The other problem may be a bad throttle body. That is the other problem I had when it had a rough idle. Good Luk and let us know what the problem is.

Did you check the easy things like oil filler cap on tight and gas cap on tight (even though that should throw a CEL)?

Unfortunately it dies before I can get around to the back of the car to grab the accelerator to keep it running. Have somebody start and hold the rpm as low as it will run then you are free at the back of the car. I think that it is probably fuel related If something got loose while you were driving then it would not of idled when you last drove the car... unless it got loose driving into your garage.. that seems unlikely... I think that if it occurred while you last drove the car, It seems tobe not affected at operating temp. you drove the rest of the day, no problems let it cool down then here you are... so I would try to get the car to a long road and run the car, and see if It clears up As for gas last, check your bank statement if you are not a cash man Jerry

just bring it to your shop and let them have a look.

Don't you have a 99 C2? Check the ICV connection and also remove and clean the valve. Unplug the MAF connector and spray the contacts with electronics cleaner and reconnect.

Thanks everyone for there input. Unfortunately it will be a few days before I can get to do any of the above as I am working out of town again. That means the car is sitting even longer

i feel your pain bud. i understand your frustration. as much as i like to dog on these guys for their modification tastes or lackthereof, and their ultra-conservative/republican/right wing habits i have complete faith in them helping u out with diag stuff like this. i'm sure it's the MAF, but hey, we shall soon find out. be healthy, be happy, the car can get fixed.

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Thanks Ben much appreciated, just sucks I cannot work on it right now and I want to. One thing for sure is that the engine is stock and will remain stock while I own the car, as I do not want another modified car in my garage, because once I start modifying the engine I get pretty crazy with it and then the car becomes un-reliable or un-streetable to drive.

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totally dude. i've so far only bought cars that i'm happy with from the factory along the power front. now with regard to the aesthetic, no car looks great from the factory save for maybe your pagani zondas of the world.

water in the tank? There is a product called dry-gas or something, sold at most gas stations.. had this problem once before... good luck! Ross

Hey thanks for posting this, I was having the same problem and this may have helped me fix it. You should check the oil filler tube very closely. I also have a 99 and when I took the airbox off a few months ago I noticed that the oil filler tube was becoming slightly embrittled and had developed a small crack in between one of the accordion pleats. My cold start idle has gotten worse and I hadn't thought much about it in relation to the leak in the filler tube until now. I just checked the car again and the crack in the tube has enlarged slightly so it makes sense. Will try a quick check in the morning with some saran wrap to see if it temporarily fixes it. UPDATE 12/12 : I wrapped the cracked section with saran wrap and taped it down well. The car was cold started and did not exhibit the misfiring and stalling that it had previously.....plus it now looks ghetto-fabulous! Guess I'll be picking up a new oil filler tube and figuring out how to install it. (proudly libertarian in my style/mod choices)

If the diaphram inside the oil separator burst, idle will be horrible too. Open the oil filler cap and check to see if there is high vacuum thorugh the tube, should be minimal. May be impossible since it doesnt idle, could just hold it just above idle to check. I also first started to think a vacuum leak, a safer way to check for vacuum leaks is to use a propane torch with a "pinpoint" hose on it and just slowly wave it all around the intake area and hoses until the RPM raises. This would be the source of the leak. '99 could have the magic diagnosis though, the ICV. If it is dead it will not let air into the engine for idle and the motor is simply suffocating (sp?). GL Steven

K996 and Tippy...great information and I will first look at the Oil Filler Tube as I noticed one-time when I topped-off the oil, that I found a small puddle under it, so I thought I had spilled some, but maybe not, maybe the tube is cracked and that is the reason for my rough idle, let's hops so. I am still away from the house, but will be home tomorrow and will look at it then and update everyone. Thanks again. Steven

Update: The car is idling fine now. All I did was remove the oil cap, wipe the tube around where the cap went, removed the o-ring seal from within cap, and cleaned both thoroughly (seal and cap). Put the cap back on making sure it was tight, and started it, car idle's perfectly. So maybe the only problem with the car was the oil cap in that it was not sealing correctly. I will continue to monitor this though. Thanks again for everyone's input and possible issues with my car. Glad to know that no money was spent on repairing it

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Man, this was almost as bad as Phil's "little green circle thingy" thread. How anti-climactic! Steven, just kidding. Glad it was something simple and free!

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Tim, I got to tell you though I am not 100% sure the problem will not re-appear just out of the blue like it did this time. But like you, I am glad it was nothing major.

Let's hope that was all there is to it.

speedy was so stressed out

Steven, I dont think it is your problem but you did mess with the oil cap and the reason I am writing. You need to open the oil cap while the engine is running and make sure it DOES NOT affect the idle. If it sounds like it wants to die out or it does die out once you pull the cap, the oil separator has KO'd or possibly the bellow that returns the oil to the block.

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Cory, thanks. So how I understand this, whether I had a problem or not: If I start the car, let it idle, remove the oil cap, the car should NOT die...correct? If the car dies then I do have a problem...correct?

OK, so I started the car just now, a bit cold outside in the upper 40's in the garage. But it started fine and idled fine, however: I removed the oil cap and the idle started to go rough. I didn't leave it off long enough for it to stall, but it was an obvious change in the idle. So is this normal? Thoughts??? But I took it for a small drive, actually saw another 996 and waved and got a wave back , no problem detected during the drive. When I came to every stop sign or stop light the car idled OK, not rough, maybe a little low for my liking (600~700), but no stalling.

Bump because I haven't heard back from anyone regarding my last post

SD I just went out and ran the car then took off the oil cap... dropped in idle and ran a little rougher! but did not die..See if yours will die If I understand what Tippy is saying, If it dies, then the oil separator is bad or ???? is bad, the second part of the "or" I am not sure what he is referring to Jerry

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If it idles relatively the same, your ok. There should only be a slight vacuum in from the oil cap. If it is rough and dies out along with a strong vacuum on the oil cap, the separator has failed. When mine failed, the cap was very hard to pull off and the engine died almost immediately, within a couple seconds. Once I put the new one in, there was a very slight vacuum when pulling the oil cap and the engine idle did not change much at all. This diagnosis was given to me from 99firehawk.

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There is a rubber hose that is called the bellow (accordian shaped) that is part of the oil separator. It returns the oil dropped out of suspension back into the crankcase, sometimes these crack. I am not 100% on whether this would have the same effect on the idle though but I have heard someone here replacing like 3-4 on their car before, the thing is a PITA to get on the nipple of the crankcase.

How does turning the air-conditioner on affect your idle? When I have my A/C on, the car idles smoother. It doesn't die or anything when it's off, it just runs a little bit rougher but no big deal - it's always done that as far as I remember.

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Thanks much appreciated for the information. So I started the car again, removed the cap and it didn't die although it seemed like there was good vacuum present, but not enough to stop me from removing the cap easily. So I am thinking it is OK, the idle changed very slightly. Where abouts is the separator BTW? I have no history on whether or not my car has had the separator or bellows replaced.

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Yep I have the same results. A/C ON a little higher idle and smoother. A/C OFF a little rough idle but like you, no big deal unless it drops below 600 rpm's which it doesn't. It use to surge but then I cleaned the ICV and that cleared it up. I was even thinking to raise the idle a little but not sure exaclty what to adjust or if that is a good idea or not. This new issue seems to have been solved but we are determining whether or not I need to replace anything (i.e. separator or bellows).

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AWESOME, the separator is not your problem! The separator is on the drivers side, front of the engine. You can see it if the driver side rear tire is off.