I need your advice. I just completed a timing belt service on my 86.6 928. It ran great for a day and a half and then began missing badly at idle, sometimes dying. Once the revs get to 1500 or so, the engine smooths out and seems to have full power. I have rechecked the TB and it seems to be perfect. I am now in the process of looking for vacuum leaks, old & loose hoses and checking the spark plugs. I have heard the board mention left bank and right bank electronics related to ignition threads but I don't fully understand what is being said. Can you give me some advise and educate me on what to look for?
Thanks.

 

More info pls. Cold engine? Check Temp sensor II? how many miles on the wires? Pull both coil wires too and examine ends. I had loss of power at speed, reconnected w/o actually seeing inside the connector, it helped. 1000K later I removed the wire and found green corrosion on one of the connectors. Nothing like that corrosion anywhere else on the car, but it had to be affecting that bank. HTH.

 

Wow, now there's a rare model year!

 

Yes, there aren't many 86.6 models left. My bad.

The engine can be cold or hot. It is missing. The plug wires are Nology and look good................no corrosion, but I have not tested for continuity yet.

 

Make sure the coil wires are seated properly, sometimes they get worked loose while working underhood in that area.

Jim R.

 

check the plug wires , check injector electric connectors , coil wires since you had the caps off . If you have or can borrow an inductive pickup timing light that makes it easy to check for spark on the wires. All the 32 valve engines one cap / coil runs 4 cylinders two on each bank and not all four on one bank but 2 and 2 .

 

I will check all ignition wiring connections and then get the old timing light out to see if all plugs are getting fire. Thanks for your input.

 

I found it! During the reassembly after replacing the TB, the throttle rod came off of the throttle body. To get to it, I removed the large center intake tube that mounts to the throttle body and the two side air plenums. In the process of replacing this after attaching the throttle rod, the rubber sleeve that is used to connect the intake tube to the throttle body, got pinched and caused it to tear a hole in it. Age and heat had made it more susceptable to tearing. This caused the engine to suck air directly from the atmosphere as well as through the MAS, resulting in driving the ECU nuts and the engine running so lean at times as to cause missing. So, the moral of the story is to check everything, especially the last things you touched. Thanks for all your suggestions.