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Discussion Starter #1
Buddies 97 Plymouth Neon Expresso was running normal then simply would not start. Have not yet performed key on/off but diagnostic tool called out "multiple cylinder misfires. I haven't been able to evaluate it yet but am suspecting the timing belt, crank or cam shaft sensor. The other thought I had is a faulty ignition module.

I am not very familiar with the 2.0 liter 16v DIS non-turbo power plant.
 

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Discussion Starter #2
Well, I am going to take it apart today. I have a timing belt ready to install, I will check the base timing 1st and look for evidence of broken/fragmented teeth.

If the timing is correct and the belt looks good, should I replace the crankshaft or camshaft position sensors?

I also thought that the ignition module (the device that the coil pack plugs into) could have failed, this happened to me on a 94 DIS Pontiac Firebird; has anyone ever seen that failure on a 1st gen Neon?
 

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Diagnose this before taking it apart if you can. The cam and crank sensor signal should show as 'present' on a scan tool while cranking. Don't just replace them without cause. Does it have spark and fuel?
The coil pack and injectors are fed by the ASD relay for (+) 12 volts and the PCM controls the ground side to turn them on and off accordingly. Without a crank sensor signal, there will be no spark or fuel. You may hear the fuel pump hum briefly in the rear when the key is first rolled on.
If you take it apart and put it together with new parts and still don't have a starting vehicle, you run the risk of having introduced other problems during the operation. Best to get an answer now as it sits.
Multiple cylinder misfire (P0300) would make me want to look at plugs and wires first to see if they are fouled or gas/oil soaked. If the timing belt has failed, you may want to verify for bent valves with the valves closed and air pressure in the spark plug hole first before taking it all apart first as the head will have to come off for valves.
Get familiar with the Neon engine before starting out with this, get a service manual.
 

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Discussion Starter #4
ImperialCrown; thanks for all the good advice. I went to work on it but the battery was completely dead. I hooked up my charger and let it to charge completely.

Further research has suggested that the coil pack is a frequent failure and the head gasket too. I am going to perform Key on/off, and run standard diagnostic for OBDII. I have 2 independent systems to run codes other than key on key off.

What I know so far is that the auto was reasonably well maintained. It was running well and making mid 30's for fuel economy in mixed city and highway driving. I am anxious to get it running.

In regards to what else I know, it does crank, so according to your write-up, the crank sensor is working. I did examine all the plug wires and the coil. The wires were in modest condition for used; the coil pack looked sound.
 

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Coil packs weren't that frequent a failure.
The head gasket problem was mostly a heavy oil leak in the rear. That was remedied by going to a multi-layer steel (MLS) headgasket. If the back of the engine is reasonably dry from oil, it has probably been changed. It would still start.
If the battery went dead, the stored codes and freeze-frame information are gone. If you can crank it, listen for even compression. A code may show up while cranking.
This is an interference engine, so hopefully the belt hasn't failed. It has a 102K mile change interval and it is best practice to replace the idler and water pump also while you're in there.
A car can still crank over with a bad crank position sensor. The sensor just tells the PCM that the engine is turning and when to fire the coils.
 

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Discussion Starter #6
ImperialCrown: battery terminals where horribly corroded, so charger was not able to effectively recharge the battery. Cleaned both the terminals and the connecting nuts/bolts: I also cleaned the battery Ground to the chasis, then the engine Ground to the chasis (leaving 2 more grounds to clean). After cleaning those 2 system grounds my microprocessing charger started going through de-sulfide cycles. I stopped them to put on a 10A charger; switched to 50A briefly to attempt to start. Barely anything, not a full crank situation. Switched to 10A and performed Key on/off. This yielded code # 12 and # 14. Since the battery isn't fully charged, I left it to charge overnight.

There was enough charge to operate electric windows, stereo and most observable electric systems. I did hear the fuel pump spool up. I did not use my alternate OB2 code retrieval diagnostic tool but prior to sitting for 5 months, the former owner used the diagnostic tool and reported "multiple misfires".

Thank you for your continued interest.
 

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Discussion Starter #7
CORRECTION: the Key On/Off codes I pulled are 12 and 55. I was finally able to get it to turn over yesterday. I cranks and sounds like it wants to start but doesn't or can't. Today i am going to shoot some starting fluid in, check for spark and look at each spark plug.

I did unhook the vehicle speed sensor (VSS), in an attempt to rule it out as the culprit. It made no change. I am also cleaning the throttle body (T/B) as it is very, very caked with deposits on the intake manifold side (engine). I was unable to get any stored information from the care as the battery was uncharged for a period of time. The code readers were unable to pull anything even when used while cranking.

The battery terminals and attaching hardware were particularly corroded, this has been corrected. The battery is currently isolated from the vehicle and experiencing microprocessor controlled de-sulfide cycles. I am thoroughly cleaning the T/B and the transmission and front lower grounds left to clean.

ImperialCrown, thanks again, as it would be favorable to determine the problem before I attempt fix it. I do learn a lot from troubleshooting when I can keep my head clear. Today I will have something to offer if I don't solve it out myself.
 

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Discussion Starter #8
Finally got it running, here is what I did:

-cleaned the battery terminals and attaching hardware.
-charged the battery with de-sulfide microprocessor charging system.
-cleaned all the grounds in the engine bay, including the headlight grounds.
-swapped in a know good coil pack.
-disconnected the VSS to rule it out as a potential fault, then reconnected it.
-removed and thoroughly cleaned the throttle body (T/B), including the throttle position sensor and air input control sensor, then re-installed.
-removed the paper air filter element as it was damp.

RESULTS:
1) after cleaning the battery seemed to respond better to charging but couldn't hold a charge high enough to sufficiently crank.
2) after de-suldfide charging, i determined the battery was unsuitable for use.
3) after cleaning the engine bay grounds and the T/B it reluctantly started with starter fluid.

Since then I have changed the spark plugs, cleaned the coil pack terminals and added dielectric grease, performed an oil change to 5w30 synthetic with a PH8 oil filter. It is running pretty nice but needs fresh fuel, the fuel in it is at least 7 months old. I have devised a Cold Air Intake system and am incorporating a 52 mm T/B from a 98 Automatic Neon in the morning.

The belt looks OK but I am going to replace the timing belt/water pump and tensioner as a preventative measure, since I don't know how long they have been on this 98 Plymouth Neon Expresso. After fixing it the owner sold it to me.
 
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