Car sometimes won’t shift out of 4th

[ZEN357]

I'd get it in to a shop and have it checked out before something bad happens to your Transmission.

[Overflow]

Originally Posted by ZEN357

I'd get it in to a shop and have it checked out before something bad happens to your Transmission.

It spent this week in a shop. Checked for codes. Came up with nothing. Went through the cars computer and saw that the abnormal shifts were computer commanded.

Now we're trying to figure out why the computer commanded it. Which points it to electrical issues.

[CFD]

Originally Posted by Overflow

Wouldn't a sensor trip a CEL?

But your explanation of why it wouldn't be a software update definitely makes sense..

It depends on the sensor and if it is an intermittent fault.

A good example on how a signal problem not triggering a cel would be with my tapshifters. If there is a bad connection or poor ground the it will cause a fluctuation in the ohm output causing a shift or not allowing a shift. No codes will be thrown and it could work perfectly again depending on temperature, humidity, vibration or any number of factors.

[UBB]

Originally Posted by CamaroFred

I have to lean towards ColdZuzion's analysis.

I don't know why you think a software update is going to fix anything if it has been working fine for 8 years.
Personally, I have never had a auto last more than 70,000 miles, some much, much less, and after that they always went less and less between rebuilds. But I beat the snot out of them.
Hell, I blew a differential out of a car with ~4500 miles once. .

You solved your own mystery. You have an end user issue not equipment quality issue.

[qcman]

Originally Posted by Overflow

It spent this week in a shop. Checked for codes. Came up with nothing. Went through the cars computer and saw that the abnormal shifts were computer commanded.

Now we're trying to figure out why the computer commanded it. Which points it to electrical issues.

I'm just curious which computer commanded the shifts the ECM or the TCM (trans one)?

[Overflow]

Originally Posted by UBB

You solved your own mystery. You have an end user issue not equipment quality issue.

My first car was an auto (Nissan Maxima) and it had 223,000 miles when I traded it in for a new Civic.

Originally Posted by qcman

I'm just curious which computer commanded the shifts the ECM or the TCM (trans one)?

I'm assuming the ECM.

[pnwdan]

Have you looked at the throttle body? The computer reads the input from the throttle body to decide when to shift. Could be a failing throttle body. If its failing but hasn't failed it wouldn't throw a code. Just send bad info to the computer.

Sent from my SM-N950U using Tapatalk

[Overflow]

Originally Posted by pnwdan

Have you looked at the throttle body? The computer reads the input from the throttle body to decide when to shift. Could be a failing throttle body. If its failing but hasn't failed it wouldn't throw a code. Just send bad info to the computer.

Sent from my SM-N950U using Tapatalk

I'll for sure check it. Another member told me to check to see if the MAF sensor is lose.

[ColdfuzionTN]

Any update on your issue?

[Overflow]

Originally Posted by ColdfuzionTN

Any update on your issue?

No. Gonna look to Dyno Steve to see if he can see anything.