Hello everyone - a lurker turned into a poster today. So, while the prius has no transmission.... mine does get some transmission slipping - like issues.. 2007 prius, approx 93k miles on it. The main battery was replaced (under warranty) at 88k miles In MA. (I use to live in CA, moved here 2014). Around 66-68 miles while accelerating, and the engine spinning away, all of a sudden you feel a small loss of power, then it tries to engage again, then power loss., if youve red-lined and over revved a manual (or a triptronic) in 2nd gear, ull know what I mean.... In the past, it would happen rarely, in CA., in very hot months, driving from IE to the OC from work... I drove from MA to NY a few months ago, and noticed that after driving it hard, for an hour or so up and down hill, it had the same revving issues.. At times the engine is really loud, it's almost as if its driving in B, it "feels" heavy, or at a lower gear... even though ., there are no gears.... Today morning., I left the prius on for 5-10 minutes... in Boston (suburbs)., it was 2 degrees and very cold windows... the prius doenst like the cold (as its parked outside)... as i drove away, the car drove heavy, accelerated heavy., and the second I got on the freeway, at hit around 65 or so., it started it power loss-gain thngy... coasted around 65 with slower engine acceleration (less hard on the pedal) and it made it to 70., got off., got to work., parked it.... Usually if its been sitting there a while I think it gets back to normal., I bought some ATF-WS a few months ago to get it changed,. but I cant seem to find anyone in the greater boston area who is good with a prius.... would love any suggestions? but coming back to the main issue.... .. I plan on changing cars mid next year (to another newer prius)., and I dont want to spend much on getting a few more months out of it... Id also hate to sell it with the issues that I know exist today...
welcome! anyone can change the tranny fluid, it's a simple drain and fill. make sure you use the approved toyota fluid. never had any dash warning lights? might be worth checking for dtc's. could need some cleaning: throttle body/maf, pcv, injectors etc. is the air filter clean?
only time the dash warning lights came on were for the issue with the main batter - after that, no lights. Lost some tools on the move here, so I'd have to get a new torque wrench , already have the (correct) fluid.... wondering if this will solve/help the power loss/jump issue though.... the heavy sounding engine and the hot/cold triggers seem odd for an issue with needing a clean..... I'll know in 10 minutes if the issue from today is still there...
Intermittent problems are always the hardest. I agree with bisco, I'd start by getting a Mini-Vci with Techstream and read all of codes, or take it to a mechanic that has a tool that can read all of the Prius ECU specific codes (a standard OBD reader can't read all of them). There are a lot of things it could be, but what's coming to mind is perhaps a loose connection to one of the senors is causing the ECU to switch back and forth between limp mode and closed loop. It's not rare for a hard bump to cause a connection to not work for a split second or two, therefore to cause the more severe codes that cause check engine lights to turn on, the computer usually waits until it can't read a sensor for a significant amount of time (eg. 10 seconds), which perhaps hasn't occurred yet. Problems in the fuel system (clogged fuel filter, failing pump, etc.) can also cause engine surging/backing off events. Techstream will tell you if the car has reported misfires as well (would take many for the car to throw a code). Really it's hard to say without more data.
As these do NOT have anything like what one would call a "transmission", a fluid change did not and will not "fix" your symptoms. Prii have two motors (MG1 & MG2) connected to a planetary gearset, there are ZERO valves, clutches, solenoids etc, both motors are always direct-connected to the gears. Variable speeds are achieved by varying the ratio of the planetary speeds, including reverse.