Engine misfire above 2500 rpm
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Joined: Oct 2014
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Engine misfire above 2500 rpm
2004 neon 2.0 engine
I have been working on this problem for some time and need help. During a run on the freeway, cam code came on. I replaced the cam sensor and no more problems/codes. 1 month later got a Crankshaft sensor code 339 with mil light during my return home on the freeway..The car Missed, backfiring if I pushed the engine RPM 2500 RPM. I replaced the sensor and still, the car has the same problem. I got another sensor and still had the same problem. tested wires at the sensor for 5 volts, ground, were in specifications. The signal wire from the computer while bumping the starter was low. I am down to two things the computer or the target ring. Has anyone had problems with target rings failing? Car has 115000 miles on it.
I have been working on this problem for some time and need help. During a run on the freeway, cam code came on. I replaced the cam sensor and no more problems/codes. 1 month later got a Crankshaft sensor code 339 with mil light during my return home on the freeway..The car Missed, backfiring if I pushed the engine RPM 2500 RPM. I replaced the sensor and still, the car has the same problem. I got another sensor and still had the same problem. tested wires at the sensor for 5 volts, ground, were in specifications. The signal wire from the computer while bumping the starter was low. I am down to two things the computer or the target ring. Has anyone had problems with target rings failing? Car has 115000 miles on it.
Captain
Joined: Jul 2016
Posts: 529
Likes: 18
From: SW Va
I see you don't have any replies yet & it's been a while, none the less I'll see if I can get things started. Scan for & post up All trouble code Numbers, as they can help focus a trouble shoot.
Did some Event on the interstate precede the latest high rpm miss woe? Higher rpm, or under load miss is usually spark oriented, so make sure your plugs gap is in spec & the plug wires & ignition system wiring to electrical connectors & their pins/ sockets to sensors, coil pack & computer are installed & tight, are in good condition, no insulation cuts, bent pins, spread sockets, wimpy wire strand crimps, or corrosion.
At warm idle, after dark, there shouldn't be any visible arcing & sparking around the coil pack, plug wires, or plugs. If they are suspect, you might try spritzing them one at a time with a spray bottle of water & watch for a break down arcs & sparks light show at wimpy or damaged insulation spots.
If you have, can borrow, or come by the inexpensive but powerful ELM scan tool & running a diagnostic software on the viewing device of your choice, that can put up the cam & crank sensors PID on its dashboard in the Oscilloscope mode, to see how their wave form looks & if there is any noise / hash / AC ripple on the signal & if there is half a volt or more, suspect faulty alternator diodes, So check the 12 volt DC output at the alternator for AC ripple noise.
You might go here https://troubleshootmyvehicle.com/ch...-of-articles-1 & review the trouble shooting outlined for your suspect part, or system
Some beginning thoughts for consideration, let us know what you find.
Did some Event on the interstate precede the latest high rpm miss woe? Higher rpm, or under load miss is usually spark oriented, so make sure your plugs gap is in spec & the plug wires & ignition system wiring to electrical connectors & their pins/ sockets to sensors, coil pack & computer are installed & tight, are in good condition, no insulation cuts, bent pins, spread sockets, wimpy wire strand crimps, or corrosion.
At warm idle, after dark, there shouldn't be any visible arcing & sparking around the coil pack, plug wires, or plugs. If they are suspect, you might try spritzing them one at a time with a spray bottle of water & watch for a break down arcs & sparks light show at wimpy or damaged insulation spots.
If you have, can borrow, or come by the inexpensive but powerful ELM scan tool & running a diagnostic software on the viewing device of your choice, that can put up the cam & crank sensors PID on its dashboard in the Oscilloscope mode, to see how their wave form looks & if there is any noise / hash / AC ripple on the signal & if there is half a volt or more, suspect faulty alternator diodes, So check the 12 volt DC output at the alternator for AC ripple noise.
You might go here https://troubleshootmyvehicle.com/ch...-of-articles-1 & review the trouble shooting outlined for your suspect part, or system
Some beginning thoughts for consideration, let us know what you find.
