04 Prius with CVT Problem

fixitmhn · 01-18-2005, 12:11 PM

Have an 04 with 8500 miles on it with a weird CVT problem. In braking
mode going down a long hill the engine RPM all of a sudden increases
to red line (extremely high RPM). It has to be put into Neutral to
settle it down. Mileage is down 25-30% as well. Dealer is calling
Toyota Technical for assistance. The Prius Tech at the dealer told me not to put it into braking mode when going downhill. Problem is intermittant as well.
Anyone heard of this before? I also have an 02 Prius with 48,000 and
no problems whatsoever.

**efusco** · 01-18-2005, 12:15 PM

This is normal operation. Your battery is getting near full and the ICE must run to avoid over charging. Your tech should know that.

You can continue to use B-mode going down hill.

fixitmhn · 01-18-2005, 12:30 PM

efusco,
The engine RPM is almost redline and would blow the engine if I don't shift to Neutral. It can't be because the battery is almost fully charged. It also happens sometimes just with the foot on the brake pedal going downhill, and not in braking mode.

**efusco** · 01-18-2005, 01:31 PM

Quote:

efusco,
The engine RPM is almost redline and would blow the engine if I don't shift to Neutral. It can't be because the battery is almost fully charged. It also happens sometimes just with the foot on the brake pedal going downhill, and not in braking mode.

Well, I'm not sure what to tell you....I think it's b/c the battery is at full charge and I know that the sound is not something you're used to hearing, but unless it is dramatically more than I think it is it is normal.

They might be able to pull a peak RPM with the diagnostic tool or something, but I'm going to bet you they tell you that everything is normal.

It is expected and actually supports my belief in a full battery and ICE peak rpm that it occurs in both B-mode and with manual braking. Check your energy screen next time it happens...I bet the SOC is in the green and either full or 1 bar short. This is a protective tool to prevent overcharge.

DanMan32 · 01-18-2005, 02:18 PM

How would you know you are redlining? There's no RPM display. The car can sound like its reving more than a conventional car would.

I would agree, check your energy flow display for SOC and what is driving what.
B mode will tend to spin the engine unfueled, this is by design. B is for engine Braking, though it will increase regenerative braking until it has no more place to store it.

KTPhil · 01-18-2005, 03:08 PM

Since it is still under warrantee, the dealer should be willing to do a code scan for free, just in case this was recorded by the ECU.

fixitmhn · 01-18-2005, 03:11 PM

Energy display shows all normal indications, and battery charge level is usually in the blue range. when it happens. Also stepping on the "gas pedal" settles down the rpm's as well. ECU shows no codes. Toyota told dealer to verify symptoms as they never heard of this problem. I know there is no tach in the vehicle but I have driven enough vehicles in my time to know when rpm's are very excessive. Also, my 02 Prius does not do the same thing on the same hills. I know the drive systems are different, but at this point the 02 Prius is getting better mileage than the 04. The 04 didn't exibit this behavior until recently. It is not temp or speed related either.

richard schumacher · 01-18-2005, 04:02 PM

What ECU codes does it report?

john1701a · 01-18-2005, 05:25 PM

Quote:

The engine RPM is almost redline

It really isn't. The engine is artifically restricted to a 5000 RPM limit. Many traditional systems allow you to climb pass 7000 RPM briefly without any problem.

Also keep in mind that the Atkinson-Miller cycle sounds a little different than the traditional Otto and that the engine itself is closer to the firewall than usual (so it sounds louder).

SyZyGy · 01-18-2005, 07:13 PM

Well obviously the red line is at 5000 rpm as john stated.

01-18-2005, 12:11 PM	#1
fixitmhn Join Date: Jan 2005 Posts: 14 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	04 Prius with CVT Problem Have an 04 with 8500 miles on it with a weird CVT problem. In braking mode going down a long hill the engine RPM all of a sudden increases to red line (extremely high RPM). It has to be put into Neutral to settle it down. Mileage is down 25-30% as well. Dealer is calling Toyota Technical for assistance. The Prius Tech at the dealer told me not to put it into braking mode when going downhill. Problem is intermittant as well. Anyone heard of this before? I also have an 02 Prius with 48,000 and no problems whatsoever.

01-18-2005, 12:30 PM	#3
fixitmhn Join Date: Jan 2005 Posts: 14 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: 04 Prius with CVT Problem efusco, The engine RPM is almost redline and would blow the engine if I don't shift to Neutral. It can't be because the battery is almost fully charged. It also happens sometimes just with the foot on the brake pedal going downhill, and not in braking mode.

01-18-2005, 07:13 PM	#10
SyZyGy Senior Member Join Date: Oct 2004 Location: Munster, Indiana Posts: 318 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: 04 Prius with CVT Problem Well obviously the red line is at 5000 rpm as john stated.

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01-18-2005, 12:15 PM	#2
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 14,244 My Car: 2004 Prius Package: #9 Nominated 1 Time in 1 Post TOTM Awards: 0 Friends: 24	This is normal operation. Your battery is getting near full and the ICE must run to avoid over charging. Your tech should know that. You can continue to use B-mode going down hill.

01-18-2005, 02:18 PM	#5
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	How would you know you are redlining? There's no RPM display. The car can sound like its reving more than a conventional car would. I would agree, check your energy flow display for SOC and what is driving what. B mode will tend to spin the engine unfueled, this is by design. B is for engine Braking, though it will increase regenerative braking until it has no more place to store it.

01-18-2005, 03:08 PM	#6
KTPhil Senior Member Join Date: Jan 2005 Posts: 1,213 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Since it is still under warrantee, the dealer should be willing to do a code scan for free, just in case this was recorded by the ECU.

01-18-2005, 03:11 PM	#7
fixitmhn Join Date: Jan 2005 Posts: 14 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Energy display shows all normal indications, and battery charge level is usually in the blue range. when it happens. Also stepping on the "gas pedal" settles down the rpm's as well. ECU shows no codes. Toyota told dealer to verify symptoms as they never heard of this problem. I know there is no tach in the vehicle but I have driven enough vehicles in my time to know when rpm's are very excessive. Also, my 02 Prius does not do the same thing on the same hills. I know the drive systems are different, but at this point the 02 Prius is getting better mileage than the 04. The 04 didn't exibit this behavior until recently. It is not temp or speed related either.

01-18-2005, 04:02 PM	#8
richard schumacher nacreous lacquer Join Date: Mar 2004 Location: United States Posts: 4,131 My Car: 2004 Prius Package: #6 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	What ECU codes does it report?