Highway speeds not shifting, Power only at 3000 RPM

[nwaairlinkazo]

First post to this forum, any and all opinions are helpful.

I describe my situation in the video, but in essence my 1999 bonnie does not want to shift once above 70 mph. While crusing at 90 mph for example, the engine is spinning at 4000 RPM and should be lower. If i coast on the highway long enough the rpm needle will drop and when i push in the pedal, I will get no power output until i reach 3000 RPM. This is demonstrated several times in the video. This is in overdrive mode.

Video: https://youtu.be/tVdLIPwb-Yg

Is this a transmission slip issue and could be fixed with some trans fluid repair or something bigger? Outside of this issue poping up about a month ago, the entire vehicle is running like a top. Bought it down in KS and driving in MI with no rust and its a really great running machine but this issue has me concerned there may be a issue coming up.

Thanks for any help!

-TJ

[Evan0801]

Catalytic converter might be plugged. Easy place to start that doesn't cost you money is if you somehow drop that section of exhaust pipe out. However, still Could be transmission and even another issue.

[RJolly87]

I would start with a code scan, which can be done free at most parts places. There are codes that will set that do not turn on the SES light that can shed some light on this.

Otherwise scanning live data would be the best bet. It could be fuel, exhaust restriction, or any number of things.

I am not immediately blaming the transmission however. Slipping is usually apparent by a lot of rpms with no appreciable increase of speed. This could simply be the transmission holding a gear, or the TCC not locking up as well. Torque converter slip is also one of the metrics monitored by the computer too.

[redfury]

You are probably hitting the rev limiter due to sustained high RPM. That would explain the lack of power and drop in RPM temporarily. As far as not shifting, you've got something going on with the overdrive circuit or with the shifter not fully engaging the transmission into Drive. Try playing around with the shifter while at highway speed. It's either going to shift into neutral, do nothing or drop into a lower gear if it doesn't engage overdrive. You may have a problem with the solenoid for OD. A good scanner can look at that data, a better one can send the signal to shift into OD via the scan tool. Check your fluid level/conditions and see if you are getting bubbles in the fluid when you are having this problem. You won't get a CEL illuminate for a non Emissions related problem, so you may have a code and not be aware of it without a scan.

[Mcmaker]

I have exactly the same problem. In my case when i drive on highway in overdrive gear the car runs smoothly, changes gear without question but sometimes when i'm going 80-90 mph it can change the gear to lower without notice or it doesn't go into overdrive mode when i'm accelerating to highway speeds

My gearbox has been fully renovated in 2012 so I don't think it's a gearbox related problem. I'm going to look up closely to this problem, maybe i can come up with something