Please help! Having issues with my porshe.
 

Hey all,
New to the porshe community. I have a 79' 911 SC. Car ran fine when I bought it. Now all of a sudden the nightmare has began. When I start the car it runs great at 2000rpm and above. Below that wants to stall, runs rich, backfires, sputters, etc... Don't know if its a cold start issue. Ive checked for vacuum leaks. Ive replaced the O2 sensor. Replaced the fuel pump relay. now Im scratching my head. Also at cold start the idle goes up and down on its own. Once the motor is warm it runs rough and wants to stall. Thanks for any input. Will

'79 shouldn't have an O2 sensor. Post an engine number.

On the door jam it states 10/79. On the registration it states 1980. So did an 80' have an O2 sensor? because I changed one.

post a picture of your engine. with the info provided there is no way we can really help you

Have you change the fuel filter ?
Check your ignition wire set (in the dark ).
Check your spark-plugs.
Check the fuel pump.
Check the injectors.
Check the ignition head.

Look under the passenger seat if you see a box bolted to the floor you have an 02 sensor. Do you see an air pump on the left side of the engine? If you do you don't have an 02 sensor.

You need to get a set of gauges to look at the CSI system pressure. Could be the air valve.
Do you have a copy of Bentley for the SC?

Porsche.....not Porshe....sorry, I couldnt stand it :)

How did we miss that? O.K. no more FREE advice until the O.P. learn to spell the name correctly.

Do you call it a Por-sha or a Porch? Be careful how you answer this question, you can have the rest of the 911 owners on this forum p.o. with you.

backfire indicates a lean condition.

Welcome to the Forum!

You will find just about everything you need to know on this site by using the search feature. Any problem you have, someone else has also had it and the Pelicans on this site have been very generous with their knowledge. The solution to nearly every problem can be found here with photographs to help illustrate.

In my humble opinion, this is the best website on the Internet for a Porsche owner who wants to repair his/her own car. Also if I have to bring the car to a shop for jobs understandablely beyond my capabilities, I have some idea how to explain what I think may be the problem.

I purchase parts from Pelican to support the site. And, I bought a copy of Wayne's 101 Projects which is a fun read and a great way to get acquainted with the car.

Please take out your digital camera and show us your car! We LOVE pictures here. The engine picture that surflvr911SC was asking for will tell us which motor is in your car. A 1980 should have a 3.0 liter engine with CIS that does not use an 02 sensor, but it may have been replaced with a 3.2 (which would need an 02 sensor if it has Motronic ECU).

Don't worry... You are in the right place to find the answers you seek. Anything mechanical can be repaired. :)

Welcome willum....tough room...tough room.

Sounds to me like a mixture problem. I think you should check all your adjustments. Start with your timing, then idle speed, then fuel/air mixture.
Did you leave your car out in the rain? Sometimes mine would do it after a good rain. Now I have a garage. yeah!!

i have a 1982 it's 3.0 it has a o2 sensor!

My 1980 3.0 also has an o2 sensor.

That's because 1980 is when the O2 sensor was added, at first he said it was '79. I think that it's been clarified now that he has a MY 1980 and probably has the stock '80 3.0 w/ O2 sensor.

We just needed to know where to start.

I was looking for an engine number, not an engine picture. But yes, we do like pictures.

Kinda sounds like a vacuum leak somewhere... check the other posts for likely leak areas & hot to test. Check your hoses of course to make sure they're not disconnected or cracked.
Welcome to the forum...

regards,

jlex.

Ok everyone, cool your jets! I know its Porsche. Just a misspell. I will take pictures right now and get them posted. To answer most questions..... It does have an O2 sensor. It does have the O2 sensor box under seat. It recently had a tune up, points, cap, plugs. I checked for vacuum leaks, but I can check that again. I don't know if I have a K injection or if its a CIS injection. One other thing to add that may help, if I idle up to 2000 rpm and hold it there, sometimes the rpm will rev on its own, I take my foot off the throttle and the car runs perfectly fine after that point. Then an hour later you start it again and its back to running rough. ??? Thanks for all the input. Will

cis is k jetronic they are one in the same

Along those lines, did it backfire just before it started behaving strangely? Could be a cracked airbox. Not uncommon. Has a popoff valve been installed? It would look like a little toilet seat under the air cleaner.

Well first off, welcome! And since you bought the right kind of 911 (SC), welcome to the plot. Email me for more info on that one.;)

Now, about your problem... not to discount any other suggestions, but are your clock and dome lamp operating normally. Your problem kind of sounds like what happened to mine when the fuse blew on that circuit. It affects your CIS as well. Anyway, should be a quick check.

http://forums.pelicanparts.com/uploa...1231709476.jpg
http://forums.pelicanparts.com/uploa...1231709564.jpg
http://forums.pelicanparts.com/uploa...1231709719.jpg
Engine number is 6400396

Beautiful car... Congratulations!

jlex.

I just converted to carbs on my 79 SC because that CIS was such a pain in the ass. Notice everyone has said to start in different places. It's all excellent advice, but you will bechasing problems for a while. I know i was. And i have a mechanic at my disposal 24-7, it was still being a pain in the ass. Good luck finding it, i hope you have success. When you do, post it so people can take your experience into consideration also.

It looks like someone removed the A/C from the car. Car could have been tracked.

http://forums.pelicanparts.com/uploa...1231709476.jpg

You say that like it's a bad thing to track it. My car has had more maintenance and attention in the last 5 years (tracking it) than it had in the first 22. Runs/handles better too. No flame but, please be considerate to the track cars.:D

Oh and to the original poster, your car does not have points. Didi you check if the oil tank cap is loose?

willum, its almost essential to put a set of fuel gauges on to properly diagnose your condition without guessing all over the place, could be anything from a bad wur to vacuum leaks, the easiest thing i would do first is disassemble and clean you wur, it probley needs it anyway, as there is a tiny screen that gets clogged pretty easy on these old cars.

Thanks for the pictures! I told you we LOVE pictures.

Once you get the car running correctly, it is going to be fun! But till then, be patient, and don't stress out. Also, there must be a fellow Pelican who drives an SC near you.

This is off topic... But, I am drewling over your garage space! My two car garage has 3 motorcycles, and 3 floor-to-ceiling shelving units, with no room to pull a car in. The blessing of ZERO lot living is a 10-minute lawn mowing job, the curse is no room for a proper shop/garage.

Cheers!

Will, also check the air box itself, your vehicle most likely still has the original one which might have many tiny hair line cracks that are hard to see because they can be underneath or on the back side of the box. The gasket also needs to be replace. You might have a manifold loose, go over those as well. don't forget to replace those gaskets with new ones if you do so. Good luck and welcome! SmileWavy

I agree my '80 had the exact same problem. I found old dried up sealant around the pop off valve that allowed unmetered air to get into intake. It really ran like crap at low RPM. I pulled the pop off and re-epoxied it -no more problems. Check the easy stuff first.

Where did I said that it was bad to track a car? This is a newbie and perhaps he didn't realize that the PO removed the A/C. Most people who remove the A/C to reduce the weight of the car so the car can go faster on the TRACK.

My AC was removed to save me several bad words every time I had to remove spark plugs, and it was useless anyway. Same with the air pump and injectors, they're in the attic with the AC now. Hotter than hell in the summer though.

10/79 production is a 1980 model, which I guess has been established. In Europe, factories close down in August and everyone goes on vacation, when they come back in Sept. they are building the next MY vehicles. That goes for most any car on earth, including the U.S. (Except the month-long vacation doesn't happen).

Bosch K-jetronic CIS is a fine system used on countless vehicles for many years, (not just Porsches), it's relatively simple and trouble-free but when it's 30 years old it's going to have worn seals and sensors all over the place unless they've been refreshed. I think that CIS gets a bad rap because people expect it to work perfectly in an old car with all original parts. The good news is that it's very DIY-friendly, IMO, once you take the time to learn how it works. All of this advice assumes an owner with a certain degree of mechanical aptitude and a desire to learn about and repair his own car. If the opposite is true, you need to find a very reputable Porsche specialty independent shop with at least one guy who really knows CIS, otherwise you'll spend a fortune on some fool chasing his tail just throwing (expensive) parts at your car until it runs right.

It sounds a lot like you cracked your air box, (the large black plastic piece behind the air filter that is visible when you remove cover and A/F. That would be the first thing to check, it's easy to look at if you can get the two rubber straps off and remove the filter. There may be absolutely nothing wrong with your CIS, a cracked air box will make the car run like you describe. Either you or an honest, competent mechanic needs to diagnose it properly. (Goes for all problems). Diagnosis is everything, people mean well here but sometimes just start throwing info and advice out there from a 1000 miles away. Diagnose properly first.

Because most clocks in 911s doesn't operate, the clocks in most 911s are only correct two times a day.

I apologize to you all for not responding sooner , however my wife and I share this computer and she took it to work with her for a few days. I am at the point where I am chasing my tail now. I really do need a reputable mechanic to diagnose this thing. I have looked at the air box and didn't see anything blatent but there may be some hairline cracks that I cant see. Does anyone know of a good, honest, reputable mechanic in northern california? Heres one for you guys. I decided to change out the spark plugs which were black and shiney with fuel, I got to the last one and now the spark plug socket is stuck in the hole and I cannot get it out. I'm starting to dislike this car.
Just a little background on this car. My plan is to do a full restoration on it. At this point it seems that I am just cleaning out the old stuff put in by previous owners i.e. stereo, alarm system, and going through everything to make it sound, and see what needs to be done. I have a freind that races GT3's. He looked it over when I first got it and his first suggestion was to lose the air conditioner. It has never been and never will be a track car. Not that I wouldn't love to run it on the track, I cant afford the tires to do it.
Thanks for all of your advice. And by the way what is a wur? I will keep you updated on the mystery of the K-injection. Will

Willum,
WUR is a Warm Up Regulator. I have an 82 ROW SC with no O2 sensor which when I bought it had a completely blown air box along with a few other issues. The car ran but had no power below 1500 rpm. Got a new air box with pop off and installed myself. Changed out all the vacuum lines and clamped them as they were previously push fit. Once I did this and started her up the there was actual fuel spitting form the exhausts she was running so rich. I put this down to the fact that previously there was so much un-metered air getting past the crack in the airbox PO had set the mixture very rich to even keep her running. Anyway managed to get her to operating temperature just idling (took a while) then I re-did my timing, set the idle and leaned out the mixture to where she would stumble. I then progressively richened the mix till she was running smooth, I have yet to put a O2 tester near it just using exhaust smell for time being. The car now runs perfectly, no idle bounce, lots of power across the rev range and no issues so far. The CIS is slated a lot but it is a fairly easy system to understand and work on. Get yourself acquainted with it and you will have no issues. See attached pic for where the mixture screw hides...http://forums.pelicanparts.com/uploa...1232091169.jpg
http://forums.pelicanparts.com/uploa...1232091312.jpg

Try Alan at the Stable in SF. I visited his shop last week while there on business. He only works on air cooled Porsches. Nice guy and very knowledgable.

Tom Amon? He's a mobile mechanic up north that everyone loves. Just search his name.