1982 targa noobie

Superdave1 · 12-01-2007, 10:06 PM

Hi. Just purchased a 1982 targa up here in Canada. Car is in great condition. Only two issues. Cold start up, engine runs very rough for a minute or two. Runs great when warm. Warm starts, no trouble. Quick and smooth starts when warm. Second issue is the tach is dead. There has been some "creative" wiring done around the coil and cdi box. The rest of the car is near perfect, original paint with all the updates, tensioners,pop off, spring clutch. I am new to porsche but not new to wrenching on cars. I know fords and nissans(240,260,300) inside and out. I have read it may be the AAV or regulator. As far as the tach goes, does it get signal from the cdi or coil? Can you point me in right direction before I take it all apart to see how it all works? Thanks dave...

SCWDP911 · SCWDP911's Garage

welcome. I wish I could help on the problems, but I am trying to learn all I can about CIS myself. One thing I can tell you is that in my CIS books, and what I ahev heard a lot f people here say, make sure to check/replace ignition components first (new cap, rotor, plugs, wires). Next, make sure you have no vacuum leaks. At that point, you are ready to troubleshoot CIS. Another thing to tell you is to go ahead and buy you a FI pressure test gage set, but make sure it is CIS compatible. Good luck and welcom once again. BTW I like the front spoiler on that car. And what color is that?

Superdave1 · 12-02-2007, 01:48 AM

Hi: Thanks for the tools suggestion. Can never hurt to have another tool! I was looking at that very tool in a JC witney cataloge. I don't think I have issuses with any other fuel/ignition parts. The cars runs very strong without a miss when warm. I have narrowed it down to the cold start enrichment circuit. It runs so nice when warm I am almost tempted to leave it alone since I will only be driving it in the summer. Hard to leave it alone though, when I know it is not quite perfect. What do you think about the tach? Do you know where it picks up it's signal from. Coil or CDI box??? I am trying to find the black/purple wire( according to the wiring diagram) but it is no where to be found. The pevious owner has new wiring running from the coil to the cdi box. He did a nice job, but is not factory for sure. I am guessing that is where my tach problem is.

I am not sure of the colour code #. The car looks red but it is actually copper colour. Look at the passenger side front fender in the picture. That is the actual colour of the car. Very close to a shiney penny. I am a bodyman and going to repaint the front spoiler. There is a bit of road rash on it. I want to try to leave the rest of the car with the original paint. I can dig up the code # if you like. I have never seen this colour before, in my search for a 911sc. I was looking for a silver 1980 when I came across this car. The colour grows on you for sure. Thanks dave...

psalt · 12-02-2007, 04:49 AM

Hello Dave,

Yes, the tach gets its signal from the black/vio wire from the CDI box. The white/red wire at the tach goes to the rpm switch that cuts fuel above 6800 rpm. Does your car have CIS lambda (O2 sensor and box under passenger seat) ? Poor running after a cold start is a result of a lean condition and it can occur for many reasons. CIS is a collection of separate components that act independently that were calibrated for a new engine with perfect compression. Any vacuum leak or engine wear leans out the mixture. Part swapping can get expensive and you should troubleshoot first. My first advice on a new car would be to do a basic tune up, oil change, valve adjustment, fuel and air filter, plugs, rotor and cap and set timing. My experience is that plugs make a big difference on cold starts, stick with the spec Bosch normal and avoid platinum. US cars have a vacuum retard at the back of the distributor canister for emissions. When an engine first starts the transition to cold warm up is tough to calibrate and when the retard kicks in, the drop in idle speed is often enough to stall the engine. My experience is that SC's cold start much better with the retard plugged and the idle reset to 950 rpm using the large bypass screw on the TB. You can adjust the idle with your fingers once you find the screw. If you have the lambda system, there is a test plug behind the left side engine compartment cover. If you hook up an analog dwell meter to the green/white terminal, you can see the operation of the lambda system and adjust the mixture. The FV must be pulsing for these cars to run right. Almost all SC's will have vacuum leaks at the injectors sleeves. There are two seals for the injectors, an oring on the injector and an oring on the plastic sleeve in the runner. The outside orings bake and leak. Try wiggling the injectors while holding an unlit propane torch by the base if the injector with the engine running. A change in engine speed means a vacuum leak. Usually you can solve the cold stumble by fixing the vacuum leaks, setting the mixture to 30-40 dwell, plugging the retard, and using the factory spec spark plug. It should fire immediately, run at an 1600- 1800 rpm fast idle and drop to 950 rpm within a mile or two. Good luck.

GothingNC · 12-02-2007, 05:22 AM

Very nice

I like the color and front/rear spoiler combo !

PS. - Check your fuse panel for corrosion-resistance.

Superdave1 · 12-02-2007, 07:37 PM

Thanks psalt: That is just the reply I was looking for. I didn't want to go in blind. I will tread lightly. Should I purchase a fuel gauge tester? Sounds like that is the way some of the guys here diagnose running issues. Can I just run a jump wire from the CDI box to the tach to see if it comes alive? Seems to me the easiest way to eliminate a bad wire. The way I understand it, at the tach I should have a ground and +12 volts plus the trigger wire(B/VI)
Sound right? Thanks agian. It is great to have this forum to talk to guys that have been there and back and wore out the Tshirt! LOL!

Gothing NC As far as the fuse panel goes. The one under the front hood looks like brand new. No corrosion anywhere. The fuse panel in the driverside rear engine compartment is another story. The top fuse is missing that I understand is for the sportmatic trans( that I do not have) the next one down is the starting valve heater fan?? The bottom fuse is for the rear defroster. Sound right?????( according to a Haynes manual) That fuse holder assembly looks a little rough. I am going to clean it all up and put in some new fuses. Do you think the second fuse has anything to do with my start troubles? According to the book it is a 25 amp fuse. Is that correct? Thanks again. dave...

psalt · 12-03-2007, 03:12 AM

Should I purchase a fuel gauge tester?

Yes, CIS is all about fuel pressure. Think in ground sprinkler system. The supply valve is a see-saw, openned by the amount of air inhaled by the engine, offset by a separate control fuel pressure loop (more pressure, harder to move, lean: less pressure, easier to move, richer). The WUR richen the mixture during warmup by lowering the control pressure, the rich mixture for firing the engine is supplied by the CSV. Even Bosch was surprised when it worked.

On a lambda car, the fuel pressures can be spot on and the engine still can run like crap. You also need to diagnose the lambda system, which is easy with a dwell meter.

Superdave1 · 12-03-2007, 07:44 PM

Hello again Paul. Thanks for helping me get to the bottom of this. Yes the car is a lambda car. Like I said before. The car runs great after a minute or two. When warmed up, easy starts, very smooth, lots of power under way, no hesitation. It is just the cold start. If things were too far out of spec would the car still run so nice when warm? I have a mechanic buddy that has worked on Porsches before. He is coming over on the weekend to have a look. I am going to get some plugs, cap and rotor first thing. I will print all that was said here and go through it with him to see what we can come up with. I will post after we have a look. Let me know if you have any more thoughts. Thanks agian. dave...