dzaprev

hey guys I have a 1984 928 S / Auto USA model. I do not have injector pulse at cylinders 3,4 , 7 & 8 no ground . I have cleaned grounds at valve cover passenger side . grounds at relay box. This was a no start got to run was running great and all of a sudden the 4 cylinders cut out. I have no injector pulse with noid light. I do show power with test light . I am looking on AllData wiring diagram and see all those cylinders have a common point X3 where and what is X3 . Here's diagram
http://repair.alldata.com/alldata/im...tation=&links=
http://repair.alldata.com/alldata/im...tation=&links=
Where and what is X3 . Possible bad ECM or broken wire . Thinking broken wire. I don't want to split whole loom if some one has any idea where the X3 connector or splice is . Any help would be appreciated

Bill Ball

That is referring to central electric panel plug X, pin 3. Look at the panel and you should see the plugs along the bottom with identifying letters under them. X is the last one (far right), I believe. I think it's red.

dzaprev

Thank you Bill. Didnt have my iPad loaded with the AllData. Will get it running in the morning.

Landseer

My 84 USA car had what appeared to be exactly same symptoms. Was talking to Roger about this earlier in the week. Sometimes hot, sometimes cold, all of a sudden the car would stumble to the side of the road, or stop in the driveway. It would kinda chug and not restart, then flood and not chug, then after sitting it would chug some more. Had it flatbedded multiple times. Big problem was the car was being used on Navy base by son in law and daughter in VA Beach. I was in Elkhart. Wife and I did a 32 hour run in the suburban to trailer it back here because nobody down there could figure it out.

I haven't yet deemed it 100% fixed. However.... I think it is fixed.

All fusebox connections and fuses were perfect. I paid special attention to seating each of the X plug connections with a mechanics pick, for the same reason Bill Ball eludes to. Same with the dual circuit special ingnition relay with the 87 and 87a terminals, it was new, plus, I had a known-good one that I substituted with no change in symptions. All grounds perfect. Fuel pump ran. Spark on all 8. Realized with a noid light that there was injector pulse on only half of the them-- if it was a short they'd all be dead. Clean brain main connector terminals. New ignition switch, no issues. Garaged / no moisture. Nothing would fix this car. Had to be inside the brain.

I removed the outside metal cover from the brain, looking for damaged components or cracked solder traces, similar to the DME issues that plague the 951. Inside there isn't much to see, as the pair of circuit boards faced each other.

Couldn't figure out how to separate them for access. On backside of boards what traces I could see looked beautiful. No signs of moisture inside. Hmmmm.

What appeared to be, and I am pretty sure are, a pair of final stage amplifiers were visible, or maybe they are some sort of grounding switches. Anyway, they connected to the circuit boards with a couple wires. One had corrosion under the connection screw. I cleaned it.


So far the problem hasn't recurred. But I haven't given it a full road test yet.

You might want to try doing this. Easy, low risk. If it doesn't work, Rich in Arizona said he could work on the LJet brain. John in England doesn't see many of them and therefore doesn't want to work on them.

Somebody in Chicago might have a spare to test, that's another option. For yours (and maybe mine -- jury is still out) it might be deeper with same symptoms, ie, like a bad final stage amp or component on the board that feeds one side. But I think its fixed. White corrosion limited to end of one wire on a final stage amp beneath a screw.. Rationalizing / speculating, if there was ever a humidity condensation issue and a drop of moisture formed inside the brain case, this wire would probably get that inside case drip of a drop of water. And the wire, connector and screw are different metals. Makes sense to have an isolated issue here. Sorta. Let us know what you find.

dzaprev

Went to connector X . Was the pin 3 not fully clipped in. My jumper box is dead will slow charge battery and check it in a bit. I think it will be fixed that's the wire that goes to all the injectors ground side . Thanks Landseer Next year Sharks in St. Charles come on down owe you a beer for always helping

jeff spahn

Nice save Dave. Is that the one that was sitting dead there at Sharks in St. Charles?

Landseer

Gotta love a save.

dzaprev

Yes got it running after 6 years down...cleaning fuses and a couple of relays got everything working.