82 911 won't start. No spark

jenior · 03-19-2004, 10:59 PM

Just got my engine back from builder and installed in car.. Motor started and drove very smooth nice. Then second day of driving the engine shut off while driving. Pulled over and cranked engine. Motor started and drove off. One block later died again. Did this all the way home. Let car idle in drive way and it died again and never started again.. Here fuel pump and smell fuel. Pulled coil wire from dist. Cap cranked engine ...NO Spark....Got my book out and checked for whinning noise from CDI. Noise was heard. Checked for batt. volts at pos. wire post on coil with key on. NO POWER..Hmmmm..Looked at wire diagram and looks like the CDI supplys power to coil.. I think The CDI is Bad.. Someone help...Don't want to buy a new one and that wasn't it.. Also checked continuity from 6 prong plug at CDI to coil pos. coil neg. dist. pick up coil. have battery volts at red wire at plug ... cleaned all connections and still nothing..HELP...Jesse From Whittier, Ca

dean · 03-20-2004, 03:43 AM

Since I don't know much about electrical stuff. I would find a good box or coil and swap parts to diagnoss. Sorry I couldn't offer any more help. If you do find that you have to replace the box you could consider an MSD unit. When my SC died one time it was a bad coil.

ruf-porsche · ruf-porsche's Garage

Connect a 12V power to the coil. See if you can start the engine.

Looks like the CDI is NOT supplying the 12 volt to the coil. If the engine starts you need to have the CDI rebuilt or a new CDI install. Or you can open it up and see if you can find any cold solder joint.

I think Wayne fix his mother color TV by wacking it a couple of time to see if there were cold solder joints.

Doug Zielke · 03-20-2004, 06:53 AM

Quote:

Originally posted by ruf-porsche
Connect a 12V power to the coil. See if you can start the engine.

Looks like the CDI is NOT supplying the 12 volt to the coil.

No.
The CDI does not supply 12 volts to the coil. More like 400.

Jim Sims · 03-20-2004, 06:54 AM

Check the 14-pin connector on the driver's side of the engine compartment. Jim

jenior · 03-20-2004, 09:28 AM

I tried the 12v jump to the coil already and nothing..Also cleaned and checked all connections. Also checked for a signal from the dist. pickup and it shows about 668ohms to about 798 ohms in its rotation..There is a signal but seems like the CD is not doing anything with it??

Early_S_Man · 10:13 AM

Jesse,

Why did you hook 12 Volts to the coil??? Do you have the faintest idea how the CDI system works???

The CDI unit only produces the 400 Volt pulses while being triggered by a signal for the magnetic pickup coil inside the distributor ... so don't make any assumptions from your static test.

Your resistance readings are not stable, therefore you aren't making a good connection! Dirty/corroded test leads, or terminals at the CDI connector???

The diagram below may be of some use ... you can print it by right-clicking over the drawing and saving the JPG to a file on your hard disk, then print that for reference.

Here are a list of steps to do:

1. Clean all ground and signal connections ... both sides at every connector! That includes coil, CDI unit, and all braided shiend terminations!

2. Remove 6-pin plug from CDI unit and check for continuity through the magnetic pickup coil ... it should measure 600 Ohms at the # 7 band #31d terminals, +/- 10 % at room temperature.

3. Measure the AC Voltage signal at Terminals #7 and #31d while cranking over the engive ... it should measure 1.0 - 2.0 Volts AC.

4. Visually check the condition of the green trigger-signal cable as it enters the distributor ... look for any cracks or missing insulation.

Does your car have a factory alarm system? If so, read the following thread:

'82 SC Won't run

Early_S_Man · 03-20-2004, 01:36 PM

Jesse,

Did you get a big, fat spark when you hooked up 12 V. to the coil? How long did you leave it connected? By my trusty HP 48 calculator ... you were putting between 20 - 30 Amps through the primary of that $120 coil, so don't be surprised if you roasted it good!

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by Early_S_Man
Jesse,

Did you get a big, fat spark when you hooked up 12 V. to the coil? How long did you leave it connected? By my trusty HP 48 calculator ... you were putting between 20 - 30 Amps through the primary of that $120 coil, so don't be surprised if you roasted it good!

Yeah, but I bet the other electrical components will think twice before they cross him!

-Chris

jenior · 03-20-2004, 03:16 PM

Ok, guys. I only had the 12v to the coil for about two to three seconds. After I got no spark at all I checked resistance in coil primary and secondary.. All within spec from book.. 6 ohms pri.. 650 ohms sec.. And yes I do have an idea how it works and have the wireing diagram you are sending.. Was sure on the voltage going to the coil.. Again I did check and clean all connections with electric spray cleaner. The wire coming out of the Dist. is new.. I will try the other items listed by the "S" man.. Stand by.. Thanks Jesse

jenior · 03-20-2004, 03:59 PM

Correction, I WAS'NT sure on coil volts..My fuel delivery is fine..

jenior · 03-20-2004, 06:26 PM

Ok "S" man....I removed my distributer and cleaned all connections and rechecked wire and rechecked resistance. Showed about 585ohms and when I turned the rotor by the bottom gear it went up about 600 ohms. Seems like the faster I spun the rotor the ohms was higher but it was steady not jumping like it was before. I re installed the Dist. Also I checked the continuity at the 6 prong plug to the pick up and it was about 585ohms.. Then I checked for AC -Volts while cranking engine at 6 prong plug. Showed 1.2 AC Volts.. Also triple checked coil and shows good.Every thing points to the control unit now.. What do you think..She still won't start.. NO spark....Jesse

Gunter · Gunter's Garage

Jesse: Do you have someone who could lend you a CDI box? Just to see if that is the problem, they are easily exchanged. The BOSCH unit is very expensive but a used one is quite reasonable.

Doug Steinel · Doug Steinel's Garage

If your CD box is toast, you might consider converting to MSD. See Wayne's project book, project number 24 where you will find his endorsement as well as installation instructions. You can pick up an MSD box for about $100 on ebay.

jenior · 03-21-2004, 02:57 PM

Thanks Dr. "G" ...That's why I am asking for some advice/help before I buy because they cost so much.. My final test on the system was to see exactly how much voltage is being sent to the coil and my meter showed around 200 Mili volts... And acording to a few of the guys responding I should have a pulsing 400Volts..(luckily we are talking on the internet because after I said I ran 12v to the coil sounded like these guys wanted to shoot me)..LOL.. So I am safe to say not enough juice..So my final conclusion is the CD box is bad...So now my next question is , Go with a after market or keep the stock bosch??
The smog laws a very strict in California and I need it to be smog legal.Doug S. says MSD...Is it smog legal??? Thanks For everyones help..

jenior · 03-21-2004, 03:02 PM

Oh I forgot...I wish I had access to good used CD box for testing..Thanks

Doug Steinel · Doug Steinel's Garage

Can see how MSD will do anything but help emissions. Multiple sparks are helping the burn.

Gunter · Gunter's Garage

Do a search on this board for MSD, some people are are not impressed. Bruce Anderson likes the CDI. The BOSCH unit can be repaired, search around by posting a new thread on this board. Because the unit is so expensive, I bought a used one as a spare. Try the various wreckers you have in CA and post a Wanted under the appropriate section on this board. If your CD box turns out to be good, keep it as a spare.

Early_S_Man · 03-22-2004, 09:37 AM

jenoir,

My suggestion is to remove your CDI unit and coil from your car and bench test it. There are two ways to do that:

1. Wire up a test jig with all new wiring, yourself. And, when done with the test jig, monitor the output from distributor with an oscillosope at distributor and at input to CDI plug terminals, also look at output at terminal 'A' of CDI unit and at coil. Finally, with a new spark plug and cable as a load on the coil, look at the spark quality and mopnitor the output Voltage and waveform at the spark plug with suitable high Voltage probe on the oscilloscope, or with an ignition scope.

2. Take your distributor, CDI unit, and coil to Andial or TRE, and have them test it for you.

BTW, I don't recommend MSD, because too many people have installed them and claimed their engine ran so much better afterwards ... but that is comparing a CDI system with known problems and running anomalies to a new install! If they had done a 'new' install on their CDI unit and installed new spark plug wires and coil ... it would have run like new, too! Nobody has ever shown dyno data that validates the claims that MSD-equipped engines run better or produce more power than a stock CDI system, EVER!!!

I can make a stock CDI system run as good as any new MSD system, and that is why the factory chose to continue equipping the 930 Turbos with the same CDI unit and coil that your car has ... through the end of 1989 production!

jenior · 03-22-2004, 04:29 PM

Well guys , I went out and ordered a MSD for my car..A rebuilt bosch unit is $350.00 plus a coil $150.00 = $500.00...I figured I'd change the coil to be safe. I'd hate for the coil to go out on my way to Las Vegas..A complete NEW MSD ignition is being delivered to me for $330.00. If It runs the same as the stock system fine buy me as long as it lasts and cost's a lot less.....The new system should be in this weekend. I will report back on how it runs...Thanks For everyones help.. Jesse So.Cal.