2000 Nissan Maxima Transmission Not shifting properly

Tiny
JDS7345
  • MEMBER
  • 2000 NISSAN MAXIMA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
When in slow traffric the transmission often will not shift out of first until you park it and let it sit for a while then it will most likely shift. Transmission has been completely rebuilt and the transmission shop says its the catalyic converter locking it into first gear at times. It may run well for a number of days and do it again. Whats up.
Dan
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Thursday, April 8th, 2010 AT 4:41 PM

6 Replies

Tiny
SERVICE WRITER
  • EXPERT
What codes are in the computer. I would expect the CEL to come on with this and have a po420 code.

IF the converter is plugged it can be from a piece that has turned into a position that does not allow flow. You can rap on the converter and listen for broken pieces rattling around if this is happening.

This is a piece from a converter we replaced.


http://www.2carpros.com/forum/automotive_pictures/30961_converter1_2.jpg



http://www.2carpros.com/forum/automotive_pictures/30961_converter4_1.jpg



http://www.2carpros.com/forum/automotive_pictures/30961_converter2_2.jpg



IT is a honeycomb like configuration. IF a piece flips there is too much backpressure.
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Friday, April 9th, 2010 AT 2:13 AM
Tiny
JDS7345
  • MEMBER
Please address the relationship between the codes and transimission and the backpressure. The car will move in first gear at a high rate of RPM's
What are the CEL and po420 codes to a layman and will these prevent the trransmission from changing out of first gear? I will have the codes checked aslo.
Thanbks, Dan

Your response below:

"What codes are in the computer. I would expect the CEL to come on with this and have a po420 code.
IF the converter is plugged it can be from a piece that has turned into a position that does not allow flow. You can rap on the converter and listen for broken pieces rattling around if this is happening. "
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Friday, April 9th, 2010 AT 7:29 AM
Tiny
SERVICE WRITER
  • EXPERT
PO420 is the code for a bad cat typically, but there may be transmission codes or others.

Most of the time a plugged cat acts like a governor and limits the engine RPM to a fast idle. Combustion must have a release which is the exhaust. If the engine can not gain momentum because it can not exhaust, the transmission will have no reason to shift.

There are two ways that you may be able to check this besides what I already mentioned. Remove the front oxygen sensor so there is less restriction or better yet disconnect and support the front pipe. Therefore no restriction. If it runs good at that point you verified the cat. Or plugged exhaust of somesort.
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Friday, April 9th, 2010 AT 7:39 AM
Tiny
JDS7345
  • MEMBER
Thank you very much. My daughter has since found some diagnostic paperwork The code is po420 low bank one and calls to rplacing the "y" pipe (Cat I guess) Your information certainly confirms the likely problem and thanks for the help.
Smiles!
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Friday, April 9th, 2010 AT 8:04 AM
Tiny
SERVICE WRITER
  • EXPERT
My pleasure, good luck.
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Friday, April 9th, 2010 AT 10:02 AM
Tiny
WALBRIDGE2
  • MEMBER
Jds7345,

I am having what seems to be the exact same problem you are having with my nissan maxima. Have you been able to get the problem fixed yet? If so, I would like to know what the final diagnosis was, if you wouldn't mind sharing. I'd like to be able to tell my mechanic when I talk to him about having it fixed. Any information you can give me would be greatly appreciated. Thanks!
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Wednesday, July 14th, 2010 AT 5:40 PM

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