Coil life

[jim ross]

Good day fellow 928rs...I recently installed new plugs..bosch plantinum +2. since that time ive had sputtering and dying once..but usually everythings fine..i rev up to about 3000 on the street and lift and the engine dies..give it gas..nothing..i just coast w/ no gas pedal pressure..and suddenly she sparks back to life... i have a 4 year old BOSCH SILVER HIGH OUTPUT COIL. COULD THEY BURN OUT THAT FAST? IM TRYING AN OLDER COIL NOW TO SEE IF THE PROBLEM PERSISTS.. THNX J

[Landseer]

Sounds like an intermittent ground. Really.

[JhwShark]

Jim,
Definitely, a substitution test is always a good first step. A coil should not go unless subject to some excessive current or voltage. I have the plugs you use and a lot of folks still prefer the copper which I will go back to next time.

There are probably many angles of trouble shooting that you can take and I'll start with a couple that can cause this as well as starting issues...other will most likely add more color and alternatives to use.

Check your green distributer wire, the connection plug at the right fender area can become brittle cracking and split the shield wire (this wire has two leads a shield wire and a center wire; kind of like a small cable tv cable), if you have never replaced it this can be one. DO not jury rig this one. Be careful checking because just the act of checking it can cause the plug to crumble!

Check the front wire harness top section at the 14 pin connector. Corrosion at the connector, the wires on the top part of the T14 can corrode and the shielding can degrade causing shorting. Look close at the wires. leading down into the harness. A lot of the 928's get to have some of the wires re-done, me included.

Others will talk about vacuum issues and other electronics (I have CIS so I have limited assist in this regard).
Jon

[Landseer]

On an 84 I've had these problems that resulted in intermittency under load.

Bad ground strap. (corrosion hidden beneath black shroud -- also had this occur on 85)
Corroded small red power wire to electronic fuel injection.
Bad ground and passenger cam cover & passenger frame-to-block (not sure which).

[harborman]

Originally Posted by jim ross

Good day fellow 928rs...I recently installed new plugs..bosch plantinum +2. since that time ive had sputtering and dying once..but usually everythings fine..i rev up to about 3000 on the street and lift and the engine dies..give it gas..nothing..i just coast w/ no gas pedal pressure..and suddenly she sparks back to life... i have a 4 year old BOSCH SILVER HIGH OUTPUT COIL. COULD THEY BURN OUT THAT FAST? IM TRYING AN OLDER COIL NOW TO SEE IF THE PROBLEM PERSISTS.. THNX J

I have never had to replace a coil on any car I ever owned from 1955 to date! They are usually sealed pretty good unless it was damaged some how. Look else where, bad connections, most likely!

[jim ross]

thanks i wil hunt down grounds and wiring connections...LANDSEER- does the red fuel injection wire connect to the front pass side terminal? / and i will check out the wire harness pin connector..i have a new harness.. and green wire..but the old half of the pin connector still gives some trouble.. THNX! J

[Landseer]

Not exactly. The little red +wires go straight into the CE panel at V4 and V3. One of them directly feeds power to the injection relay.

The grounds are the among the very first things that you've got to clean-up on these cars. And the positive connections. And the 14 pin connector.

Under load, I've had grounds be unable to pass sufficient current and stutter / shut down the car.

I've had them to indirectly cause relays to drop out, too.

There are guides in the manual and on rennlist to the fuction of each wire in the 14 pin. There are hot ones, such as that heavy wire at terminal 14 and the offshoot wire that feeds the tmp/time switch.

[jim ross]

please elaborate on red wire / CE panel..are you talking fuse /relay panel?

[JhwShark]

Yes, the fuse/relay panel is The Central Electronics panel in the pasenger footwell under carpet. Plug V (alphabetical left to right).

[jim ross]

thnx

[Landseer]

The two shown with the arrow on this 5 speed 84 panel.
For the most part alphabetical, with alarm Z black plug with only 6 slots instead of 8 positioned near the middle of the alphabet.



Staring at the back of that V plug (mold labeled on panel , also magic marker on plug)
V4 V8
V3 V7
V2 V6
V1 V5

Jim, I went to your garage page. Nice, nice work. Still, how on earth could you do that massive restoration job and not be intimate with every wire purpose, color and CE panel jargon? I had to learn the electrical first just to keep from starting my basement on fire. Guess yours was sunbaked but not abused like mine.

[jim ross]

thanks for the pix.yes ive been through my wiring problems..but very minor..just furred over conectors..loose connectors. chasing gremlins!

[Landseer]

I'd clean the wire at the battery. I'd also remove and clean the CE panel. All the ground points on the car. The 14 pin connector. And remove and clean the jump post (several wires beneath it).

That gets you to a datum from which to build.

[Maleficio]

One question, LS. What's the most efficient way to locate all ground points?