Strange RPM jump while driving?

RO83AA

MEMBER
1996 TOYOTA RAV4
2.0L
4 CYL
2WD
AUTOMATIC
200,093 MILES

On two separate occasions, about 4 days apart driving the same distance out of town and back home, while driving (65/ 70 MPH on the interstate) the RPMs are running steady at approximately 2,600 RPMs. After driving for more than 45 minutes the RPMs jump from 2,600 RPMs to 4,000 RPMs, just for a few seconds, then drops back down to 2,600 RPMs. Then for the rest of my 2 1/2 hour trip everything is fine. No loss of power or shaking of the car when the episode happens. It doesn't happen again for the rest of the drive. I didn't get to scan my vehicle right away when I reached my destination, but I scanned it about 6 hours later and no error code was found.

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Monday, September 4th, 2023 AT 10:04 PM

3 Replies

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

When the RPM's jumped, did it feel as if the vehicle wasn't accelerating? For example, did it feel like it jumped out of gear and then back in?

Also, have you checked the transmission fluid level and condition? When you say it jumped like that, to me it sounds related to the transmission. If you haven't already, check the fluid to make sure it is clean and full.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid

Let me know what you find.

Take care,

joe

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Monday, September 4th, 2023 AT 11:16 PM

RO83AA

MEMBER
51 POSTS

Hi, so no it did not feel like the car wasn't accelerating or it jump to a different gear. I did change the transmission filter, gasket and fluids back in February this year 2023. I checked the transmission fluid level before driving back the other day, with the car warmed up after 15 mins, the level was sort of near the middle between 'Hot' and 'Cold'. I put in 0.25 of a quart.

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Tuesday, September 5th, 2023 AT 2:04 PM

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

Based on your original description, it sounds like the transmission slipped. The idea that there are no codes may simply be caused by the code type. Some require a fault to occur two times or a failure or fault to last a certain amount of time.

At this point, we have two ways to go. First, wait and see if it continues to happen and eventually sets a code or you could scan the can-bus to see if anything is stored.

CAN stands for controller area network. Basically, the different modules are tied together via a few wires and communicate with each other. This type of scan will retrieve codes regardless of the module storing them. Here is a link explaining how it's done. Note that a traditional scan tool (in most cases) can't do this.

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know your thoughts or if you have other questions.

Take care,

Joe

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Tuesday, September 5th, 2023 AT 6:21 PM