Neon runs rough then shuts down

[CharlesS]

My daughter has a 1999 Neon with 106,000 miles. She had told me several months ago that sometimes the motor will hesitate. This hesitation would occur when the car was running above 45 mph and the motor was warmed up. The hesitation would occur for 30-45 seconds then would not happen again for another day or so. I changed the plugs & plug wires but the problem continued. Finally the other week the car stalled on the side of the road. Once it had sat for 30-45 minutes I was able to start it. It ran okay at first but then started to run very rough and miss. The fuel pressure appeared to be ok but we were not getting a spark. The codes indicated that the cam shaft sensor was faulty which was replaced. The car would start and run fine for 5-10 minutes and then begin to miss & would stall. The code then indicated a faulty crank sensor which was replaced. At this point we could get no spark at all. We tested all the relays & the ignition coil which appear to be fine. The codes now indicate no crank sensor signal at the PCM.After inspecting the wiring harness it appears to have several bare wires along with many wires that the casing appears to be melting. We are in the process of going through the entire wiring harness and repairing the damage. Can anyone give any advice? Does it sound like we are moving in the right direction? Thanks

[denisond3]

I would agree its likely a wiring harness problem. I think thats a type of problem the PCM cant pick up directly. We have a 97 SOHC Neon. The engine had to come anyway out to replace the leaking rear main crankshaft seal. I did the work myself. With the engine on the bench, and its wiring harness still wrapped around it, I found plenty of semi-melted, scorched & oil soaked wiring. Where the wires ran down past the EGR valve, then around behind the engine and below the exhaust manifold - to the crank position sensor, speed sensor, and O2 sensors; the bundle was glued into one single stiff mass. Most of the damaged wiring was nearly invisible when the motor was still in the car.
In trying to separate the wires in the bundle, they would sometimes come away with no insulation at all. Some of them might have been shorting together, I couldnt tell. I removed that harness from the motor, laid it on a table under a shade tree, and spent several hours over 3 days, working on it. I replaced 12 wires, trying to maintain the original splicing arrangements in case it was important. I used teflon wire because its insulation can stand greater heat, though the stuff is harder to cut/trim, and at the junctions I used heat shrink tubing that I shrank with a blow-dryer or a bic. I also replaced the cam position sensor, as one of its 2 locking tabs was broken off, and replaced the speed-sensor and its connector, and the connector for the crank position sensor. The work wasnt hard, but it was time consuming. It would have cost a fortune to have done at a service facility. Im retired, so I had the time.
I first tried to get a better wiring harness, going to junkyards where they let you take your tools and pull-your-own parts. To get access to the harness, I removed the through-bolt from the front motor mount, then with a fence-tightener (cheap Chinese hoist) I tilted the motor forward to give me space to work at the rear of the motor. With the air cleaner housing removed I had space to get down there to undo the harness. Many of the Neons I found in salvage yards were already missing that harness! The ones I found still in place All looked just as bad as did ours. The Dodge dealer had the harness for my car's VIN - for over $600. Its not a good sign when the parts counterman knows the price of the item without looking it up in the computer! But if I hadnt been able to do the fix myself, I would have paid for the new harness from the Dodge dealer.
If you are going to try working on that wiring with the engine in place, I would advise removing the entire harness. Thank goodness I took LOTS of photos with a digital camera so I could get the wires back where they belonged. Its very important to rebundle the wiring, so the wires wont abraid themselves in the hurricane of wind under the hood at highway speeds, and its important to protect them from the radiant heat from the exhaust manifold. On our 97, the metal tube for the EGR feed runs close under the harness, and easily gets hot enough to melt the wire insulation, if the harness isnt supported as well as it was originally. An exhaust manifold can get hotter than 1000 degrees when climbing a long upgrade, even a gentle one.
When I bought the new cam position sensor and the new speed sensor, they both came with a new connector with pigtails. I installed those, as the old connectors and their wires looked ratty. Both of those sensors were reasonable, costing about $30 each.
I hope you will let us know how it works out. Since your Neon is a 1st generation Neon, you could post queries in that subforum.

[CharlesS]

Just completed reworking the wiring harness and that appears to have solved the problem. I wish I would have checked that first before replacing $100.00 worth of sensors. That wiring harness was a mess !!!!!!!
Thank you all for the advice !!!!!!!!!!!!!!!