Mechanics

NO SPARK

1998 Plymouth Neon • 4 cylinder FWD Automatic • 181,000 miles

No Spark on 98 Neon. Changed coil pack, Crank sensor, And Computer
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Shannon17872
December 13, 2010.




Have you checked for fuel pressure? You can also check for battery voltage on the dark green / orange wire in the coil pack, one of the injectors, or the small wires on the back of the alternator. Holler back with your findings.

Caradiodoc

Caradiodoc
Dec 13, 2010.
I have fuel pressure I had to replace the fuel pressure regulator and The injectors but I have no spark we checked the fuses and they are all good but the connector to the coil pack has no power. The only code that came up at one point was Fuel pump relay/auto shutdown relay but we replaced those it was fine. Had the fuses checked they are fine but no power from the connector to the coil pack

Tiny
Shannon17872
Dec 14, 2010.
Got it. Let's clear up some misconceptions. I can't think of an instance where there has been a defective fuel pressure regulator on a Chrysler product. GM has a ton of trouble with them leaking raw fuel into the vacuum hose, but not Chrysler.

I can't remember if the Neon uses a separate fuel pump relay, but regardless, if you don't have voltage to the dark green / orange wire in the coil pack, you don't have fuel pressure either. With a separate fuel pump relay, it is turned on along with the automatic shutdown (ASD) relay. Some models only use the automatic shutdown relay. In that case it runs the fuel pump along with the coil pack, injectors, and alternator.

Here's where it gets misleading. Use your test light or voltmeter to measure the voltage on the dark green / orange wire in the coil pack or on any of the injectors. You WILL see voltage there for just one second as soon as you turn on the ignition switch, then it will go away. You will likely hear the hum of the fuel pump too for that one second. That's where the apparent fuel pressure is coming from. If you don't have voltage for that one second, we gotta go in a different direction.

What you will most likely find next is that voltage does not come back during engine cranking. That's why there is no spark and the fuel pump will not be running. The Engine Computer has not turned the ASD relay back on in response to engine rotation. To clarify what I'm trying to say, you must test for voltage on the dark green / orange wire while cranking the engine. The computer turns on the ASD relay when it sees engine rotation, (cranking or running).

When the computer doesn't turn the ASD relay on during cranking, it is because of a lack of pulses from the crankshaft position sensor or the camshaft position sensor. Most of the problems are caused by the camshaft sensor. The Check Engine light should also be on and there will be a diagnostic fault code stored in the computer's memory related to which sensor isn't working. If you get a code related to "cam and crank sync", the computer has shut the engine down to protect the valves due to a jumped timing belt. If the timing marks look like they're lined up correctly, pull the cam sprocket off and check for a sheared off dowel pin. That only pertains to the single overhead cam engine.

Caradiodoc

Caradiodoc
Dec 15, 2010.
I just put a new cam sensor on it last week. We are planning on checking broken wires this weekend.

Tiny
Shannon17872
Dec 16, 2010.
Wiring rarely causes a problem so before you tear harnesses apart, back-probe the connector pins and look for 5.0 volts on one pin and 0.2 volts on another. If you find them, and since you have new sensor installed, you'll save yourself a lot of time by reading any fault codes.

Caradiodoc

Caradiodoc
Dec 16, 2010.
I gave up and put my car in the garage

Tiny
Shannon17872
Dec 17, 2010.
How much do you understand about obtaining diagnostic fault codes and about troubleshooting electrical problems? Do you know how to use a digital voltmeter?

Caradiodoc
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Caradiodoc
Dec 17, 2010.
The above question by shannon is the same problem I'm having with a 1998 neon. I have no power to the fuel rail or coil pak. I have 0.2 to 5.0 volts when performing the test at the crankshaft sensor. I replace the camshaft sensor, all the relay, battery and fuses test good. The timing marks line up just fine. I tested to see if there was power to the fuse box and there is. I have 2 codes 12 - Problem with battery connection. Direct battery input to PCM disconnected within the last 50 ign starts.
Code 11 - No distributor reference signal detected during engine cranking. Check the circuit between the distribution and the PCM.
Is there any why to bypass a sensor to see if I get a power/signal to the coil or Fuel rail?
Thank you Mick56926

Tiny
Mick569
Jan 12, 2012.
I'm sorry, history on car to above question I asked. I bouth the car a week ago. The kid I bouth it from stated that the car was running fine with a rough idle and someone told him to replace the EGR value. After he replaced the EGR the car would not start again. The Neon has only 90000 miles on it. I also tested the Neutral safey switch and that was good.
Thank you

Tiny
Mick569
Jan 12, 2012.

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