'79 Turbo Intermitant Ignition Failure

Germaneighter · 10-17-2003, 09:57 PM

Sometimes while running down the road I will loose spark. Tach drops dead. Sometimes it will restart in 5-10 minutes while other times it may be 2-3 days later before it will fire. I have had the Perma-Tune unit bench tested and it was fine. I have verified all grounds are good. New coil, wires, plugs. I did all the diagnostics in the Bentley. All checked OK.

I suspected the green lead coming from the distrib going into CDI box. The two circuits within the wire itself have continuity. I disassembled the distributor. The coil inside the distributor does not have continuity to leads "A" and "B". This looks like a simple coil....please tell me it should have continuity.

Can this piece be purchased separately?

thanks, DLG

john walker's workshop · 10-18-2003, 07:09 AM

probably the delayed ignition cut-off relay, to the rear of the rear defrost relay. it can cut power to the CD unit. to test this theory, bypass it, by removing the wire plug from it, and jumping the wire that's hot with the key on, to the red wire that goes to the CD unit. the relay has 4 terminals and a little metal tube, so it's easy to figure out if it's the right one.

Early_S_Man · 10-18-2003, 10:00 AM

DLG,

I am not sure what you mean by: 'The two circuits within the wire itself have continuity' ... if you mean the shield has end-to-end continuity, and the center conductior has end-to-end continuity, yet no continuity at the connector two terminals, then yes you may have a problem with the magnetic pickup coil.

The two leads at the CDI-unit plug [terminals 7 & 31d in the diagram below] from the green coax should have continuity, and measure 600 Ohms +/- 10% at room temperature. Be very, very careful with that distributor, as it can be damaged betyond repair with a careless mistake! AFIK, no repair parts are available.

I have no turbo-specific wiring or other info, but since the CDI-unit is the same as SC's, here is a pertinent diagram I prepared and posted for an SC ignition problem ...

Germaneighter · 10-18-2003, 06:21 PM

Warren,
When I check continuity at teminals 7 and 31D there is none. Each side of the green coax has continuity from end to end.

DLG

relkceb · 10-19-2003, 06:51 PM

I would check the ignition cut off delay relay part # 930 617 117 01 i had the same problem and thats what it ended up being. It's around $40 and would not be a bad idea to replace it considering the age of it.

Germaneighter · 10-20-2003, 06:11 AM

After I by-passed the ignition cutoff relay, the car started. I plugged the relay back in and the car would not start. I did this two or three times to verify the results. Same results each time.

I thought my problems were over. I left the jumper wire installed and was going to a local shop this morning to buy a new relay.

........the car would not start again. Now I am really frustrated.0

I'm not sure if this is related to the problem but when the car is starting, the tach will twitch slightly as I turn the key on then proceed to crank it over. When the car is not starting, the tach does not make this twitch.

Any Ideas?

Thanks

john walker's workshop · 10-20-2003, 07:07 AM

check for power at your bypass lead. see that the plug from the ignition switch is firmly pushed into the reciever just ahead of the back of the switch. be sure that the white wire to the overboost switch is tight. it's on the intake bypass housing, just below where the turbo sump breather hose connects to the air filter housing. the relay that it works is at the rear of the engine compartment electrical panel. make sure it's tight also. early 930s used the same black relay as the ones up front.

Germaneighter · 10-23-2003, 05:45 AM

I have checked all of the above. I installed new overboost switch and ingnition cutoff delay. Wires at ignition switch are tight. Relay swapped out with good one tested on horn circuit. Still the same results.

I really appreciate the help. Do you have any other ideas?

john walker's workshop · 10-23-2003, 06:59 AM

aftermarket alarm w/ign cutoff? is the green wire's insulation broken at the distributor? did you try another CD box yet? they can be off and on. someone probably has a test unit around, so you don't have to buy one. tight grounds at the coil mount? the coil is mounted on a black painted extension bracket, and that can cause a poor ground situation for the ground wires that bolt to the coil clamp. scrape away paint where necessary to get a good ground to the fan housing.

Early_S_Man · 10-23-2003, 07:00 AM

If you aren't seeing the 600 Ohm resistance of the magnetic pickup coil at the input terminals of the CDI plug, then ther is a break in the tiny 40 ga. wire inside the distributor! Another distributor is needed, as the pickup coil isn't available as a repair part!

John Walker may have a lead on a used one.

Lorenfb · 10-23-2003, 07:03 AM

The dist. pickup wire to the CD box should measure 600 ohms,
w/o the CD unit. When cranking you should get about 1.0 volts A.C.

If you have the silver Perma-Tune and/or the silver Bosch
coil, you have intermittent units. Both of these units fail
in the matter you describe.

Get another CD unit and coil to use as a testers.

Good Luck
Loren
'88 3.2

RoninLB · 10-23-2003, 07:12 AM

Quote:

Originally posted by john walker's workshop
did you try another CD box yet?

my simple ignition system experienced the engine cut-off while traveling thru Area 51. The tach would crash when this happened. sometimes I'd have to wait 15min for it to re-start, sometimes it would immediately re-start before coasting to a stop. This prob kept going on for a few hundred miles till replacement. Changed the Permatune and coil, done deal. The bad coil or Permatune bench tested OK..
whatever........Ron

Lorenfb · 10-23-2003, 07:18 AM

Right-on Ronin! You can't (usually) test for intermittent problems unless you
can duplicate all variables; e.g. vibs, heat, and etc.

Have Fun
Loren
'88 3.2

Germaneighter · 10-26-2003, 08:13 PM

Ronin,
Did you replace with Perma Tune or other brand?

Thanks,
DLG

RoninLB · 10-26-2003, 08:31 PM

Quote:

Originally posted by Germaneighter
Ronin,
Did you replace with Perma Tune or other brand?

Well DLG..
At the of time of the Area 51 happening I was in Nevada.. and by the time I figured enough was enough I was in Oregun..
So Pelican got the blue coil and replacement Permatune sent to pwd72s/Paul on priority status to keep me rolling.

So presently the new electric panel has full MSD parts, ++.
And I will carry spare coil and box/ no matter which brand.
.......Ron

RoninLB · 10-26-2003, 08:48 PM

Hey DLG,
are their any mountains or high country around those lake areas surrounding Tulsa.. maybe a river feed with beavers.. How about some hills overlooking a plain that Golden Eagles feed from ?
huh, Ron

Germaneighter · 10-27-2003, 05:45 AM

Ronin,
Thanks for the information.

We have "rolling hills".....not many mountains. Lots of rivers and beavers. Plains?-yes....golden?-usually green or brown. Some eagles.....lots of hawks.

For pure scenery sake.....I prefer south west NY state...."upstate" I think it's called.

RoninLB · 10-27-2003, 08:08 AM

Quote:

Originally posted by Germaneighter
Ronin,

For pure scenery sake.....I prefer south west NY state...."upstate" I think it's called.

thanks for a clear picture of what the Tulsa area is like.. you explained it perfectly.. thanks........Ron

pwd72s · 10-27-2003, 08:18 AM

Wow! Great engine panel Ron! Is one of those "buttons" a remote start feature? A marine grade MSD? Tell us more!

RoninLB · 10-27-2003, 09:49 AM

Quote:

Originally posted by pwd72s
Is one of those "buttons" a remote start feature? A marine grade MSD? Tell us more!

Hi Paul.
It's a bit of a long detail story, but I'll try.

My latest neurosis.
The engine comp elec was based on keeping the CD box with clean electric. Even though the only computer is the CHT & EGT gauge, the CD elec has to be very good. [The computer is grounded at the engine.]. The front bulkhead panel is for carb fuel lines, regulator, filter, etc. The .080 thick preforated metal has 1/4in holes and threaded rivits are used for mounting the components.

So 8ga AWG from big starter lug hot goes to new marine fuse & buss bar. The MSD hot goes in direct contact with starter hot wire connector at buss bar.

2 seperate grounds.
Stock left inner fender/comp liner ground and 8 AWG from under car chassis ground to fender lug. The buss bar 8 AWG ground feed lug comes from being positioned between the inner fender ground and the under car feed lug. . The MSD ground is positioned in direct contact with the chassis feed lug at the buss.
The MSD unit is the marine version. If it's good enough for the pounding and engine compartment heat of ocean racers it's good enough for me. And marine electrics has to pass higher standards than auto electrics.

Staying with the program is the engine comp starter jump. A hot from the buss goes to a marine momentary 10amp button that triggers a 75amp Bosch relay. The relay has a 10 AWG red feed from the buss. The relay has a 10 AWG yellow output to the starter solenoid. The left button that is above the red light is a momentary on to check water level in the 2 micron marine fuel filter. If red lite triggers then the sensor is conducting thru water.. It's not hooked up now cause I'm not sure if I wanted it?

CD box and coil is on rubber vibration feet. The stock elec panel has stock inner fender vibration mounts. The new preforated metal panel has 1/8 fuel line sliced to line the outer edges to act as vibration mounts and is secured with small diameter safety wire every few inches.

Naturally all of the above is with 24kt gold wire connectors.

The rest of fuse panel will be C2 motorized spoiler, big watt rear back up lite solenoid to prevent backing into forest trees[again] , fog machine, engine comp lite, etc.

Some of ideas that were incorporated were triggered by Loren and Warren .........Ron