Mazda Protege Revving

I googled my symptom and came across an old post that sounds exactly like my issue, except that my car is an automatic with 98k miles. What could it be? Should I go to Autozone or similar to get a computer diagnostic check or bring it straight to a mechanic?

June 2010 edited November -1 in Repair and Maintenance
hello, I have a 2001 mazda protege lx w/ aprox 120,000 miles manual transmission. for the past few days i’ve noticed a change in how it shifts & i fear its getting worse. it feels like it has low power/acceleration, when i apply the gas it seems to over rev (higher than usual rpms) in order to accelerate. i also noticed going 70 mph on cruise control today, i tapped te cruise control to increase speed another 1mph or so & it over-revved in order to accelerate onloy another mph (jumped a couple thousand rpms & made revving noise it did used to do for aonly a slight increase in speed, then onceit catches it goes back normal rpms or aprox 3000) which kind of mirrors what it feels like it needs me to do to increase speed when not on cruise control. i puch the gas slightly & it doesnt seem to accelerate as well so i have push harder & it revs more than it should before it catches & increases speed sort of like normal. this is new worring me as i fear an expensive repair

Autozone does not do computer diagnostics. Autozone reads fault codes with a basic code reader, a piece of equipment that is almost useless in the professional shop.

The post from 2010 describes what appears to be a failing clutch. You state your car is an automatic, so I doubt that post will help you.

Doing my homework… could it really be that I just need a bottle of fuel injector and a tank of premium gas? Oh wouldn’t that be a nice, quick, easy (cheap) fix!

The other ideas I’ve seen (besides the dreaded dying transmission) are:
transmission fluid is low
vacuum sensor malfunction
shift solenoid
pressure issue/leak/bad seals

Please tell me it’s something like this and not the transmission!
What’s my next step?

So, I assume you have a 2001 Mazda Protege and it is having problems shifting. With automatics, you need real diagnostics, not a parts getter with a code reader. To start out cheap, check the transmission fluid first. Get the engine nice and warmed up by driving it around for a few miles. Park on a level surface and keep the engine running. Under the hood, remove the transmission dipstick, wipe and reinsert to get a good reading. The fluid should be between the dots or in the crosshatching. Also check the fluid condition. It should be nice and pink. If it is orange or brown, that’s bad. Also, if it leaves dark streaks on the rag, it’s dirty and needs to be changed. If it looks like it needs a change or it has been more than 30,000 miles since it was last changed, a change may help. A pan drop is best, a fluid exchange is also Ok, but don’t let them talk you into a transmission flush. These can damage the transmission. If none of that helps, you need a transmission shop to diagnose the problem.

Concur w/BK above, it sounds like you need a basic transmission service to start. Hopefully that will solve it, otherwise continue the diagnosis from there.

OP writes ... transmission fluid is low vacuum sensor malfunction shift solenoid pressure issue/leak/bad seals

Please tell me it’s something like this and not the transmission!

Those items are part of the transmission. It’s possible a problem like this might not require a full transmission rebuild, but just to replace one of those items or in the case of the third, just tighten the valve body to spec to tighten up the seals.

@BustedKnuckles and @GeorgeSanJose THANK YOU!

Update: the transmission fluid is fine. I didn’t have the problem this morning but was only accelerating uphill in the city, not on highway. I bought some fuel cleaner and will use it this weekend when my tank is low, before I refill it. The guy at O’Reilly recommended Sea Foam motor treatment.