Look on page 240-21, in the Fuel Injection section under Control Pressure Regulator.

Here’s my WUR. Number on top say 086 or 980 depending which way is up.http://forums.pelicanparts.com/uploa...1560115575.jpg

I found the part number. It is an 072.

I unplugged the plug to look at it and plugged it back in. Now it won’t start.

Cold engine check.........
 

Mark,

Let the motor sit overnight and check the resistance of the WUR heater. To do this, remove the electrical plug to the WUR and measure the resistance (Ohms). Use a multi-tester and set the knob to resistance (Omega symbol). Take note of the ambient temperature when you did this test. Keep us posted. Thanks.

Tony

Here is what it means........

When you disconnected the FV, the idle smoothed out. This means that someone enriched the mixture via the 3 mm allen screw to add more fuel when the FV wasn't working. You can fake the system out this way, and it will run ok at idle and partial load but at WOT it will run very lean. This is because when the FV system isn't working, the WOT isn't working either - so no WOT enrichment which means it will start backfiring just like you described.

So the solution is to lean out the 3 mm mixture screw until the idle smoothes out WHILE THE FV IS OPERATING. You can get the mixture close by feel but the best way to get it spot on by setting the CO. at your idle speed. If you have a Cat I think the spec is measured and set to ~.7% after the Cat or if SSi's 2-3 %. Don't quote me on these numbers- they should be under your engine department

The FV is an enrichment valve that is cycling from 40-60% while it is operating. When not working it is 0 or closed- NO enrichment. So, if it idles ok when not working - that means the mixture has to be set rich for it to idle ok.

If you don't have a CO meter take it back to the shop and have the set the CO to spec as well as the idle to 850 rpm's or what ever your spec.

Better yet, call the shop and ask them what they set them to......

Once you get the FV system back in order you will feel that you gained 20 HP.

Keep us posted.......

Just to answer your question, backfiring through the intake usually means too lean. Backfiring out the exhaust usually means too rich.

Will attack it again Monday. Hopefully closing in on the problem. Will update. Thanks

Here is a chart for control pressures for your WUR. It's the bottom one.http://forums.pelicanparts.com/uploa...1560177328.jpg

Well not good. Car will not start. Plug going into WUR is kind of loose. That cause it not to start? All I did was unplug it and plug it back in.

Might be time to take it to a shop (gulp). I’m about 90 minutes north of LA. In between Bakersfield and Santa Clarita valley. Anyone recommend a good shop? Thanks

Cold start...........
 

Mark,

You don’t need the WUR plug connected to get your motor to start. What you need is to know your fuel pressures. Without a pressure gauge kit, you are wasting your time trying to diagnose your problem. You are doing a lot of guess-work troubleshooting trying to find the culprit/s. If you are lucky, you might succeed. But you can not rely on LUCK all the time. A fuel pressure gauge kit is a mandatory tool for any fuel injection troubleshooting regardless what fuel injection system your are working. Without one, you are putting yourself to fail. You probably already know it by now. Buy or borrow one. You need it. Period.

Tony

Good to know about the WUR plug not making a difference in starting. I’ll look into getting the gauge. Hopefully that brings me to the problem. Thanks

My understanding is that you can flood a CIS system with excessive cranking. I recently had a similar issue when "tuning" my 81Sc - I turned the 3mm enrichment screw too far to the right and the car would not start (in a parking lot on my way to a car show). If you flood the car be careful about fuel in the oil. If you can smell gas -pull the plugs and like Tony said let it sit over night. Im thinking what Dave Kost is thinking - that most likely is your issue.

Im not suggesting you jump in and start turning the enrichment screw - because it sounds like you are still figuring things out - but the Bentley manual helps you understand a bit more on page (240-6)..

Here is my thread on my initial idle issues http://forums.pelicanparts.com/porsche-911-technical-forum/960597-strange-idle-issue-cis-problem.html

In this thread I posted youtube videos of my pressure readings- I show how the fuel pressure gauge is hooked up. This is valuable information (a must to get started).

I would read everything you can on the K-jetronic (with Lambda) system. The video that was posted explaining the system is a good start. I also know of 2 other books ("How to tune a Bosch fuel injection by Ben Watson, and Bosch Fuel Injection and Engine Management by Charles Probst). As well as the CIS primer posted in the CIS for dummies thread and the K-Jetronic Porsche Workshop Manual by Robert Bosch

There are not a lot of mechanics that understand this system - it hasn't really existed on cars since the early 80s.. Ask your mechanic (when you find one) if they understand the system - if they dont, keep looking.

I would work on getting the car started and perform some simple diagnostics - the group here would be able to get you up and running a lot cheaper than a tow and a mechanics bill - plus you'll learn a lot about your little jewel.

Thanks for the info. I ordered a pressure gauge so it will be a bit before I get the results. Meanwhile I’ll do my reading!

Posted to your other thread:

The is an old saying about CIS:
There are 3 kinds of CIS Owners:
1) The guys with working CIS systems are probably out driving their cars so they won't reply.
2) The guys that tinker with their CIS systems and have them royally screwed up will keep you running in circles with suggestions.
3) The guys that have spent a fortune on Webers will tell you they're great to justify their expenditure to themselves.

That said, before you mess with the CIS components, be sure:
-You have NO Vacuum leaks in the induction system.
-You have fresh plugs;
-If you have points, have fresh points and the dwell is set correctly;
-Your timing is set correctly
-You idle speed is set correctly; and
-Your advance is working properly.

Once these are spot on, then and only then, you should do the CIS pressure tests and figure out if the CIS components are working properly.

Messing with the CIS parts will sometimes mask an underlying problem and it will keep returning.

So, what did TRE find ?

+1 on your list Harry. I would add one more if you have a car with a cat, make sure the cat is functioning properly - i.e. not plugged. This turned out to be the culprit with my idle problem after spirited driving. I also had many other issues that I was able to resolve thanks to Tony and others - and measuring fuel pressures and using a homemade smoker to find and eradicate air leaks. I'm now a member of group 1 in your list.

Troublemaker.

My car would not pass smog. TRE fiddled with the timing and EFI and it still wouldn't pass smog. So they swapped the Jetronix with one from a later SC and it passed smog. They put my Jetronix back in because they didn't know how to test it our fix or whatever the car really needed. Dave said here's your smog certificate, give me $1,100 and good luck.

I asked what specifically they did and he didn't know. I told him it was now running worse. Idling up and down and wouldn't idle at all. He said that is because they tuned it for their elevation and I live in the mountains (yes, he said that). The car ran great at all elevations before his mechanic got his hands on it. I've known Dave for many years and he has worked on my cars before. This was a shocker to me.

Anyway, enough of the past. I ordered a fuel pressure tester and smoke machine. I greatly appreciate all the help I'm receiving here and will try to solve my problem. Waiting for equipment and will report back.

Mark, sounds like you're in a frustrating spot. And the thing that makes this forum so cool - many folks offering help - can work against you when talking about CIS. Too rich, too lean...doing XY&Z fixed my car....etc. May seem overwhelming?

I have a suggestion of my own: just follow ONLY Tony's advice and, for now, tune eveyone else out. He has talked others folks, just like you, through this. He has a method and, as is required when solving mechanical/system problems, it is fairly linear; jumping around and not being disciplined will NOT work.

BUT, if you accept Tony's help, you'll need to follow his directions to the letter and answer his questions clearly and not go off on tangents or following other people's suggestions....that destroys the linear process of deduction required to understand you car. As Tony has said, you will only make matters worse by stabbing around.

All the others posting on this thread will respect what you're doing and give you the space. And remember that Tony does all this gratis...you just have to submit to following his direction to the letter. He can be very blunt, but it is because he needs to understand where you are at in the process....if you don't understand the question, kep asking until you do. It WILL be worth your time and effort.

Full disclosure: I was recently working on the electrical side of my 82's CIS and asked for help. Tony responded and gave me something to check. I did something different and went on with life, thus failing to follow a step Tony suggested and as a result, I created a significant problem that could have been avoided. My bad, 100%...hubris and maybe some laziness at play.

Here's another way to say it: there's nothing worse than someone who asks for help then blows-off the exact advice he asked for. Don't be that guy!

If this sounds beyond what you're comfortable signing-on for, have it flat-bedded to one of the other shops mentioned. I hear the right kind of things about M. Bixen / Red Line, but in SoCal you have many choices. No dishonor in that.

Best wishes, John/CT.

Tony knows a lot about CIS, and so do many other people that post in this forum; not sure how tuning everyone else out is a good option . . .