tdrain4 Posted April 30, 2021 Report Share Posted April 30, 2021 Hello. I got a buddy who bought a dodge neon. It was tore down, ready to get a roll cage welded and hit the dirt track. It ran to load and unload. Sat over winter and now has no spark. Any idea on where to start? Bad wire somewhere? Or a sensor issue? He put new plugs, wires, and coils in it. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
Rick.Cook23@yahoo.com Posted April 30, 2021 Report Share Posted April 30, 2021 I’ve had similar problem. Car ran fine all race weekend, but when came home to unload, car wouldn’t start. No spark, no fuel pressure, nothing. It would crank, but never even sputter. Spent a lot of time checking wiring, fuel pump... finally found it. Crankshaft position sensor. If your car is EFI (pretty much every car built after 1985 or so), your fuel injection and spark is controlled by ECU/computer. When computer sees no signal from crankshaft position sensor - it cuts fuel and spark. Some cars also have camshaft position sensors - but those seems mostly for ECU to speed up or slow down the spark timing- not out right cut spark and fuel like the crankshaft position sensor will. I swapped my crank sensor after 2 full weekends of pulling my hair out - sum bitch fired right up!! These 2 sensors - crank and cam position sensors - can be pricey if your just swapping parts to try to eliminate things. $70-$100 each at parts store. But you can get them at salvage yard for like $10-$20 each - or I found mine on RockAuto brand new for $10 each! At that price, even if it doesn’t solve your problem, these are good spares to have. Quote Link to comment Share on other sites More sharing options...
tneker Posted April 30, 2021 Report Share Posted April 30, 2021 7 hours ago, Rick.Cook23@yahoo.com said: I’ve had similar problem. Car ran fine all race weekend, but when came home to unload, car wouldn’t start. No spark, no fuel pressure, nothing. It would crank, but never even sputter. Spent a lot of time checking wiring, fuel pump... finally found it. Crankshaft position sensor. If your car is EFI (pretty much every car built after 1985 or so), your fuel injection and spark is controlled by ECU/computer. When computer sees no signal from crankshaft position sensor - it cuts fuel and spark. Some cars also have camshaft position sensors - but those seems mostly for ECU to speed up or slow down the spark timing- not out right cut spark and fuel like the crankshaft position sensor will. I swapped my crank sensor after 2 full weekends of pulling my hair out - sum bitch fired right up!! These 2 sensors - crank and cam position sensors - can be pricey if your just swapping parts to try to eliminate things. $70-$100 each at parts store. But you can get them at salvage yard for like $10-$20 each - or I found mine on RockAuto brand new for $10 each! At that price, even if it doesn’t solve your problem, these are good spares to have. +1 specifically on a neon this is where I would look first. I would also recommend genuine mopar replacements. Neons also run a ASD relay which can create a no spark situation. neons.org is a very helpful website for anyone who runs a neon. Quote Link to comment Share on other sites More sharing options...
Timothy G. Elliott Posted April 30, 2021 Report Share Posted April 30, 2021 9 hours ago, tdrain4 said: Hello. I got a buddy who bought a dodge neon. It was tore down, ready to get a roll cage welded and hit the dirt track. It ran to load and unload. Sat over winter and now has no spark. Any idea on where to start? Bad wire somewhere? Or a sensor issue? He put new plugs, wires, and coils in it. Thanks for the help. In 1994 I had a friend at the race track have the same issue, would crank fine, had dealership tech working on it all Saturday, Sunday morning still wouldn't start, I told him I could get it running and after allowing me to scan it, live data showed 5.0 volts on all the sensors, key on engine off, tapped a dedicated ground wire to the throttle position ground wire to the battery ground, and it fired right up and saved his weekend! He ended up having the dealership replace his engine wiring harness, but they never found why the ground was open. Hope this helps. 2 Quote Link to comment Share on other sites More sharing options...
Black Magic Posted April 30, 2021 Report Share Posted April 30, 2021 (edited) A few of us are (un)fortunate enough to race neons. A few common pointers 1) Get a proper mopar repair manual for the car. They are cheap online, as no one else really wants 90s dealer books 2) There are differences in the wiring 95, 96-some 97, and 98-99. Get the book for the year you have. Main split is 95-96+, change in ecu and engine wiring after 95. 3) Do you have power to the engine sensors with the key in the run position. Should be 5 or 8 volts. 4) If no power to engine sensors with key on, common issues on these cars is a fault in the ASR circuit. It is the power for all the engine sensors and other critical engine functions, designed to shut everything down in the event of fire\short\crash. If any part of the engine harness shorts you lose everything. Often the harness on the back of the engine for the crank, o2 and alternator gets melted and shorts taking out the entire ASR circuit (usually blowing the ASR fuse) 5) Some functions in the engine power circuit are ground controlled on the neon. A bad ground to the switch, relay, etc will cause issues. Had this happen on a neon I was doing cage work in, I had unbolted something that was (unknown to me) resting on the switch panel providing an accidental ground path. The car would run if the tools in the car were randomly arranged to provide ground to the panel the switch was grounded to, when they moved the car would turn off. 6) If you have power to the engine sensors depending on the year you only need crank and tps, or crank, tps and cam (96) to at least get spark and try to run. Check the harness for cracks\broken wires at the TPS, crank and coil. Those take a beating, get hard\cooked over time and can create issues. Crank sensors are cheap, if you question it. They are incredibly simple cars electrically and with a real manual things will get alot easier.... Edited April 30, 2021 by Black Magic 2 Quote Link to comment Share on other sites More sharing options...
Mopar 4 Life Posted April 30, 2021 Report Share Posted April 30, 2021 What year of neon. If sbec, check rear crankshaft sensor wiring. It gets a lot of heat. second would be to check ASD relay circuit. The steering column sometimes has a problematic mfs switch connector that could trip off the ASD relay circuit. 1 Quote Link to comment Share on other sites More sharing options...
tdrain4 Posted June 5, 2021 Author Report Share Posted June 5, 2021 So i swapped, cam and crank sensors. Still no go. No spark or fuel pressure. Got about 8 volts to sesnors and 5 volt to tps sensor. Motor seems to turn over slowish. Could it be turning to slow? New battery and a jump pack on it still doesn't help. Thanks Quote Link to comment Share on other sites More sharing options...
tdrain4 Posted June 5, 2021 Author Report Share Posted June 5, 2021 On 4/30/2021 at 4:23 PM, Mopar 4 Life said: What year of neon. If sbec, check rear crankshaft sensor wiring. It gets a lot of heat. second would be to check ASD relay circuit. The steering column sometimes has a problematic mfs switch connector that could trip off the ASD relay circuit. On 4/30/2021 at 7:18 AM, Black Magic said: A few of us are (un)fortunate enough to race neons. A few common pointers 1) Get a proper mopar repair manual for the car. They are cheap online, as no one else really wants 90s dealer books 2) There are differences in the wiring 95, 96-some 97, and 98-99. Get the book for the year you have. Main split is 95-96+, change in ecu and engine wiring after 95. 3) Do you have power to the engine sensors with the key in the run position. Should be 5 or 8 volts. 4) If no power to engine sensors with key on, common issues on these cars is a fault in the ASR circuit. It is the power for all the engine sensors and other critical engine functions, designed to shut everything down in the event of fire\short\crash. If any part of the engine harness shorts you lose everything. Often the harness on the back of the engine for the crank, o2 and alternator gets melted and shorts taking out the entire ASR circuit (usually blowing the ASR fuse) 5) Some functions in the engine power circuit are ground controlled on the neon. A bad ground to the switch, relay, etc will cause issues. Had this happen on a neon I was doing cage work in, I had unbolted something that was (unknown to me) resting on the switch panel providing an accidental ground path. The car would run if the tools in the car were randomly arranged to provide ground to the panel the switch was grounded to, when they moved the car would turn off. 6) If you have power to the engine sensors depending on the year you only need crank and tps, or crank, tps and cam (96) to at least get spark and try to run. Check the harness for cracks\broken wires at the TPS, crank and coil. Those take a beating, get hard\cooked over time and can create issues. Crank sensors are cheap, if you question it. They are incredibly simple cars electrically and with a real manual things will get alot easier.... I got cam and crank sensors swapped out. Still no go. About 8 volts to them. And 5 volts to tps sensor. Quote Link to comment Share on other sites More sharing options...
Black Magic Posted June 7, 2021 Report Share Posted June 7, 2021 Still no fuel pump voltage on initial key on? Can you even read codes from the ECU? Similar thread to what you are experiencing. Scroll to the bottom. Ground path and fragile wiring repairs seemed to fix this guys issue. Would check with the FSM procedure that you have power to the coil, crank and cam sensors while cranking. Track down the fuel pump lack of power, that will most likely lead to the wiring issue in the engine\ecu circuit. They can pop ECU's, although I have never experienced that failure. Quote Link to comment Share on other sites More sharing options...
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