Crankshaft and Camshaft position sensor errors

Tiny
TGONGAWARE
  • MEMBER
  • 1997 CHEVROLET CAVALIER
  • 2.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 153,000 MILES
So, I've been dealing with this issues for a few years, but it has gotten worse. The car will start and run, but then it will randomly drop the RPM's by about 50-100 and feel kind of like it is misfiring. For a long time, just keping the RPM's above 1000 while idle would keep it from dying, but now it will die frequently. I've replaced both the crankshaft position sensor and the camshaft position sensor. I've replaced the timing chain (I read somewhere this can happen from a stretched chain), Ignition control, plugs, boots, and coils have all be tested. Fuel filter and catalytic converter have been replaced as well. When it first started happening I took it to a Chevrolet dealer and they replaced a few things and then they told me I need a new engine (this was 4 years ago). It passed safety and emissions for 4 years after, I find it hard to believe that it could be the engine or reluctor wheel if it has been running for that long. Any ideas on what else to try?

Thanks
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Tuesday, July 21st, 2015 AT 10:39 AM

9 Replies

Tiny
JDL
  • EXPERT
If you got trouble codes for those sensors, what were the actual codes. Yes, I can look it up, but, if more than one code for one sensor, then, I don't know which code? Before I replace a sensor I try to check the connector wiring circuits, probably ref voltage--ground and signal for that sensor. I can't go by what somebody else did or said. All I can do is make suggestions on what to check, you have to do the testing.

After a vehicle warms up, it's not unusual for the rpms to drop a little.

You say it dies frequently, does it die at idle or going down the highway? If at idle, check and clean the idle air system.

Check cylinder compression, I haven't looked at your compression specs, but usually the minimum is around 100 psi. It may run with less than that, but, with poor compression, it may not run correctly.
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Tuesday, July 21st, 2015 AT 11:07 AM
Tiny
JBAUTO1588
  • MEMBER
2.4 are nightmare motors but it really sounds like a iac motor problem. "Idle air control" its located in the side of the throttle body any car that the rpms drop that low will misfire and run terrible. There pretty cheap and will need a small torx bit to change. Also while you in there grab some carb cleaner or intake cleaner and remove all the carbon build up for the new sensor to read better.
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Tuesday, July 21st, 2015 AT 11:09 AM
Tiny
TGONGAWARE
  • MEMBER
Sorry, I was at work and decided I would try posting the question and didn't have the codes in front of me. They are p0335 and p0341.

It dies both at idle and when driving on the highway. Although currently it dies too much for me to get to the highway. It doesn't die until it has warmed up some, it does fine while it is cold.

Could this be from exhaust back pressure? I changed the catalytic converter a little over a year ago, but the muffler is original and fell and broke the flange last year when the hanger bracket rubber failed.

Crankshaft position sensor checked out okay on electrical tests I'm able to perform. I don't have a scope so I only checked resistance and signal voltage.

Thank you for the help.
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Tuesday, July 21st, 2015 AT 5:04 PM
Tiny
TGONGAWARE
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I cleaned the iac and it still acts the same. It's there a process for checking the iac?

Thanks
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Tuesday, July 21st, 2015 AT 5:57 PM
Tiny
JDL
  • EXPERT
With cleaning the idle air system, you also remove the throttle body and clean it real good, especially the small passages, you can use a wire to make sure they aren't clogged and clean the throttle body throat. If the problem is caused by something else, doing that probably won't help except as maintenance.

Did the codes go away after you replaced the sensors or are they still present? The po341 means the cam and crank sensor signals are not in sync. Most often caused by the cam sensor and or wiring circuit. Is there an extended crank time?

From here, I can't tell if signal is dropping out when it gets warm?
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Wednesday, July 22nd, 2015 AT 9:52 AM
Tiny
TGONGAWARE
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Codes are still present. It always sets the p0335 anytime it dies. P0341 only gets set sometimes when it dies.

It initially starts right up, but after it is warm it requires an extended crank time to restart it.
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Wednesday, July 22nd, 2015 AT 10:19 AM
Tiny
JDL
  • EXPERT
I don't know what else to tell you?
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Wednesday, July 22nd, 2015 AT 12:58 PM
Tiny
TGONGAWARE
  • MEMBER
So, I played with it some more. The signal remains there the whole time. I did notice that the frequency on the 7X reference signal/Crank Sensor varies from 68 to 75 Hz at idle (constant RPM). That seems suspicious to me. Do you think it could be the reluctor wheel missing some teeth?

Thanks for all your help!
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Thursday, July 23rd, 2015 AT 5:19 PM
Tiny
JDL
  • EXPERT
Sorry, I don't know about the hz?
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Saturday, August 1st, 2015 AT 11:53 AM

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