atb

Neither of LED's on the module are lighting up. A fellow 928'er checked the injector clips with a multimeter and it showed that the four inner cylinders were dead until we jumped to "dumb-*** mode" module. Then all eight injector clips read the same with a multi meter. It didn't have any affect on how the car ran however.


Again it just seems strange that the four cylinders that are firing are showing the same electrical and mechanical information as the ones that aren't firing.

Do I need to call in a priest for an exorcism?

fabric

Except that the problems are spread across the two distributers. If one distributor is offline, you would lose the outer 2 cylinders on one side, and the inner 2 cylinders on the other side. ATB is losing both of the inner 2 cylinders. Which is probably why he's about ready to pull his hair out, as that makes it a pretty perplexing problem - it's not in the coils or rotors.

Adam, have you double-double checked the routing? NO, that shouldn't matter, you can make them work by pressing down. All new leads, plug to plug?

AO

Strange indeed. You have air. You have spark. You say you have compression. And it sounds like you have gas. I guess the next step is to verify that the spark is ocurring at the right time. I'd take a multimeter and check for continuity from the coil wire to the plug wire. Rotate the engine (by hand) until you show continuity for that cylinder. Then pull the plug, and by using a piece of wood dowel rod, you should be able to tell when if the piston is at the top of it's compression stroke (although it could be 180* off).

morganabowen

Sounds like your on "Limp Mode". It has happened to me and it seems a common ailment for later model 928s. This thread seems to recur every month or so .

atb

Chris wrote:
I have. The timing belt covers have the cylinders numbers cast in right above their respective distrubutor towers. My own S4 is at the shop and I've done a side by side comparison (as have others just to make sure I'm not missing something).

I can't associate the motor running smoothly with the pressing down on the plug wires because I replaced the wires with no change, unless perhaps the plugs aren't grounding when they are in the holes?

I'll have to put a timing light to them while the motor is running to see if they are sparking while the motor is running.

Man, it sounds so implausible, but I guess anything is possible, especially with these cars.

atb

I wish it were true Larry, cause the fix would be easy. My symptoms don't exactly match up with limp mode syndrome as it isn't coil specific.

AO

Wait a minute... it's on both distributors? Oh.. well then I haven't a clue.

atb

Don't go bailing on me now Andrew, you were on a roll.

Bill Ball

Pardon me if you did this already ---If you pull the spark plugs on the non-working cylinders, attach them to the leads and short them against the heads, try to start the engine, do you see good spark?

Reinstall the plugs. Does the run on all 8 if you squirt a little starter fluid into the MAF?

If so, it is a fuel issue to the dead cylinders.

John Speake

>>>>>>>>>>

Hi Adam,
You can use a "Spanner" or Hammer to do just that - this is the way the Tony found a connector problem on one or two of his injectors. Inspect the injector conenctors carefully, check there are no bare wires touching under the rubber boot, which happens of the insulation breaks away.

Jim bailey - 928 International

Remember Tony H and his injector wires shorting out? the insulation was shrunk back and somehow wires got twisted during all his R and R with his supercharger /injector changes. Since this car has the igntion monitor relay perhaps just one injection harness is shorted ?

j.kenzie@sbcglobal.net

Are the bad cylinders on the same injector wiring harness? Someone must know. If so check connectors for shorts because, as Jim said they would all fail on the harness with just one short.

AO

Actually I was thinking about Tony's issues (back in the day), when I was typing earlier, but it sounded a bit different. You might want to go back and research his posts to find out how he diagnosed it. Sorry I can't be more help than that right now.

AO

No. This is how it is working (=0) and not working (=X).

.... Front ....
5=0 .... 1=0
6=X .... 2=X
7=X .... 3=X
8=0 .... 4=0

Now you're gonna make me look this up in the wiring diagrams.

AO

The ignition circuit controller will shut them down as such: 1,4,6,7 or 2,3,5,8. Basically, right side or left side - so I don't see (at least onthe diagrams) how just cyliders 2,3,6, and 7 can be affected. Hmmm ???? Need to think a bit more on this.