Please read this before you go about trying to troubleshoot your problem!
Pearl #1: Don't just start swapping parts.
This is expensive. You might get lucky taking this approach. You also might empty your bank account before you find the REAL problem.
Pearl #2: Be methodical.
You have to start somewhere in diagnosing problems, but try to work through problems in a progressive approach rather than jumping all around.
Pearl #3: You might need some tools.
You don't have to have a lot of tools to properly troubleshoot these problems, but you will need some. A set of CIS fuel pressure gauges is really a must. There just isn't much you can effectively do without them. Yes, they may cost $100 or more, but if you are keeping the car for any length of time they are a must-have tool in the toolbox.
Pearl #4: Listen to the advice you are getting.
I didn't understand a lot of the advice I was getting at first. Listen to it. Think about it. Ask more questions if you don't understand. Just don't ignore it. Others have been there, done it and got the T-shirt. In most cases, they are telling you something for a good reason.
Pearl #5: The search function is your friend.
Chances are the question has been asked and answered before. Use the search. If you are still having problems finding the answer to your question, by all means ask the question.
Pearl #6: There is certain information we need to know in order to help you.
When you decide to start a post looking for advice, don't forget to tell us some important information such as:
- What year is your car?
- Is it a US or RoW model?
- Is it the original engine or a different year engine?
- Has it been modified from stock?
- What are your symptoms? Be as specific as possible.
- Did the problem start over time and get worse or did it start suddenly?
- Is there anything that you do that makes the problem better or worse?
- How are the cold starts?
- How are the warm starts?
- Do you have a pop-off valve installed in your airbox?
- Tell us as much history on the car as you think is relevant.
Pearl #7: Don't mess with the fuel mixture right off the bat.
A lot of people make the mistake of messing with the mixture setting hoping that will fix the problem.
A quote from Tony (boyt911sc): "But the most blatant suggestions in the CIS troubleshooting threads is adjusting the fuel mixture for starting or running problem/s. We are not dealing with a carbureted system where you could turn the mixture screw left or right until you get some result. It does not work this way for fuel injection systems."
You might improve your situation, but chances are you are probably covering up another underlying problem. Worst case you are just making it worse and adding more complexity to the problem that needs to get sorted out. And remember that you're only adjusting the idle mixture. If you have gone over everything else, THEN adjust the mixture using the 3mm Allen screw. If you have fixed other problems, you might be changing other factors that will lean or richer the mixture anyway so it's best to save that for last. See Pearls #2 and #4.
Pearl #8: You might have more than one problem.
Don't get frustrated or give up if you fix one thing and find that didn't completely solve the problem. These cars are now 30+ years old. You can get it back to the way it was supposed to run. It is entirely possible that the previous owner didn't know what to do either so something they may have done in an attempt to fix it either just covered up the underlying problem or made it worse. See Pearls #2 and #4.
Pearl #9: Make sure you have the correct part(s) for your year model.
I've noticed a few times that people have posted about a problem only to discover later that they had the wrong part for their year model. I've noticed this especially with the Warm-Up Regulator (WUR). Since some of the CIS components are NLA, maybe this is being more commonplace as people go to places like junkyards hunting for parts. In any case, this is something worth verifying when you begin to troubleshoot problems as it will save you a lot of headache later. Refer to the charts at
Jim's Basement Workshop for the correct part numbers for your model year and the
Porsche PET for more help.