Inconsistent rev above 3000 RPM

Tiny
PEABOJONES
  • MEMBER
  • 2006 CHRYSLER PACIFICA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 69,000 MILES
My vehicle will not rev over 3000 at idle. With pedal fully down it revs to 3000 steadily then starts to waiver wildly.
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Monday, November 22nd, 2010 AT 7:42 PM

6 Replies

Tiny
KHLOW2008
  • EXPERT
Fuel injected vehciles are equipped with a rev limiter and when the rev limit is breached, the PCM (engine computer) would cut of some of the cylinders to prevent over revving. This is the phenomenon you are experiencing but the rpm is too low to be correct.

Most likely the PCM is getting the wrong signal and cutting of the cylinders prematurely.

Was any repairs done prior to this occurring?
Get a scan done to retrieve for trouble codes and let me know the exact code if any found.

Quite often this problem is due to a fault in the throttle position sensor or MAF.
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Tuesday, November 23rd, 2010 AT 2:03 PM
Tiny
PEABOJONES
  • MEMBER
I had trouble for the two prior months with occasional drained battery issue. I did not notice the inconsistent rev issue util my last jump. I swapped out the battery (which I had tested first and it was bad). The car starts now but the rev issue did not go away. Thinking of having alternator checked next?
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Tuesday, November 23rd, 2010 AT 5:01 PM
Tiny
KHLOW2008
  • EXPERT
Yes, get the alternator checked.

When the battey goes flat completely, it most likely is a parasitic drain or some electrial component had not been turned off. The PCM would lose all it memory and requires relearning to get back to working properly.

Some highway driving coupled with city driving and returning to the highway again would most probably get the relearn cycle complete.
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Wednesday, November 24th, 2010 AT 12:22 PM
Tiny
BBEARW
  • MEMBER
Did driving fix your problem? I am having the same thing with my 2007 Chrysler Pacifica and my alternator was bad and the battery did drain flat a couple of times and now it will not rev over 3000 rpm. I just put in a CPS (crankshaft position sensor) and still no change. I am just wondering if driving fix your problem that way I know that I will not get stranded again with this car.
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Thursday, December 16th, 2010 AT 7:12 PM
Tiny
OHFIVEPAC
  • MEMBER
Hello, I am having the same exact issue. 2005 Pacifica with 3.5L and 75,000 miles. Codes are P0300 and P0306, which means cylinder misfire, specifically number six. This happened about 10,000 miles ago (engine light came on). I read about a specific problem with carbon buildup on the valves in this engine, mainly due to a faulty spring retainer design. Chrysler has issues a service bulletin on the known issue. I used some Redline s1 fuel system cleaner with a full tank, engine light went off, I cleared the codes, and it stayed fine for like I said about 10,000 miles.

But engine light came on again recently, and the codes were the same. A new issue now is that the motor will not rev past 3000 in neutral or park, even if the car is rolling in neutral, exactly like what the original poster describes. When driving, it revs fine all the way to 7000 (red line) when I hold back the trans by using the auto-stick for shifting.

I did use the fuel system cleaner again, and the engine light is now off, but I did not clear the codes, and the rev problem in neutral and park is still there. I guess I can live with it, but I know its not right. Any ideas for instance why the rev limiter is doing this at only 3000? Is the PCM doing this because of the misfire codes?
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Thursday, April 14th, 2011 AT 1:26 PM
Tiny
KHLOW2008
  • EXPERT
What are the latest codes present?

Misfiring can trigger something resulting in the PCM going haywire. Alternatively it could be the problem that is causing the misfire codes to show, it could either be the chicken or egg first.
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Thursday, April 14th, 2011 AT 1:36 PM

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