2004 prius won't accelerate

the hv battery will run low and your acceleration will be limited until the battery recovers

 

It happens sometimes. .and I got too turn my car of on few times thin it's okey

 

I have too for the car too Kool off its really hot here

 

your battery is probably weakening, how many miles on her? 165,000. yep, that might be it.

 

Here are a few updates on my slow accelerating Prius. I received my mini VCI cable and there were only two codes stored: P0420 (Catalytic Converter below threshold) and C1242 (ABS IGI something).

I changed the downstream O2 sensor recently and that didn't help so I got a new Magnaflow OEM Grade Cat installed this week. That cleared the MIL and the P0420 code. C1242 has not come back up in more than a week now, since I cleared it with Techstream. Since I was working on the car I decided to also change the spark plugs and the engine air filter, as I don't have the full car maintenance history and the plugs seemed pretty nasty. I changed the traction battery last month and the 12V battery last summer.

I can now predict the specific moment when my car will accelerate at a turtle pace; it is when the traction battery reaches only one purple bar. Unfortunately this happens almost every day now. Very strange. I've owned a Prius for almost 10 year (this is my 2nd Prius 2G) and I've never seen this until lately.

I checked the inverter coolant pump. It runs and I can see the liquid flowing, but it is not constant. It does sound like an aquarium, but goes "nah neuh nah neuh nah nah nah [short pause and repeat]. Is this what it should sound like? In a way I almost wish that it's not, so I can finally pinpoint my problem, but I don't want to change parts just to change parts.

I read that our AC compressors runs on the HV battery. It may be worth noting that I live in the South and it's been in the 95+ for a few weeks, but I've been in the South for 8 years not and I've own a Prius since I moved here and never had that problem were the HV battery would get drained to the point of affecting acceleration. Maybe my A/C just needs recharging?

I'm confused and can't wait to fix that problem! All comments are welcome! Thank you!

 

DTC C1242 means that either ABS #1 or ABS #2 relay is not working - or there is a problem with the associated wiring, the brake power supply or the skid control ECU.

How well does the air conditioning system work? If the refrigerant level is low, the system will be less efficient so the air conditioner compressor needs to run a greater proportion of time, draining the traction battery more than otherwise necessary.

Or it is possible that your traction battery is wearing out, losing capacity but the 28 modules are wearing evenly so that a fault code is not logged by the traction battery ECU.

 

Thanks Patrick, I'll look into changing the ABS relay.

The AC seems to be working fine.

The traction battery is new. I changed it in June. I though I had gotten a faulty one because that problem started happening shortly after getting the new battery and got the new one replaced for free, but that didn't help.

 

What does "new" mean? Does this mean that the battery came from a Toyota dealer parts department - or does "new" mean that the battery is newly installed in the car but is actually "remanufactured", or used?

What mpg does the car achieve?

 

what conditions cause your battery to drop to one bar?

 

The battery is remanufactured by a company that specializes in hybrid battery for Prius and Camry. That's all they sell: Prius Hybrid Battery- FREE Installation Service

The car gets in the low 40's (39-41 mpg) on an all highway trip (calculated based on miles travelled and gas purchased). That's actually not that bad, but still probably 5-7 mpg too low, compared to what I was getting a few months ago.

City thought is pretty bad. I get high 20's to low 30's - probably 27-32 mpg.

Normal driving conditions cause the SOC to drop, especially on a in-town trip. I can leave the house in the blue bars, I'll see both the ICE and electric motors contributing, then siting at a light the SOC will slowly go down and by the second or third traffic light I'll be on the last two or very last purple bar. The problem is that the ICE doesn't seem to start charging the traction battery until it's too late. When it gets to the last purple bar the car accelerates really slowly and the ICE struggles to charge the battery and move the car at the same time.

If I had never driven a Prius I probably wouldn't think anything of it, but this is my second Prius and I've owned Priuses for almost 10 years now and I don't think I've ever had averages below 40 mpg until recently.

 

I would say there is some likelihood that the battery currently installed is marginal - not bad enough to trip a fault code, but bad enough so that it is easily depleted with the AC compressor running and therefore cannot aggressively help MG2 to get the car moving from a stop.

 

That would be very disappointing, but hey you get what you pay for! I only paid $800 with free installation.

About a month after changing the battery I called the vendor because this was happening and they changed it for free. They were very surprised and appologetic. These battery come with unlimited mileage and 12+ months warranty depending on the option you get. This is the second battery from them and it's doing exactly the same thing as the first one; which leads me to believe that there is something else going on. The installer also called me shortly after installing the "second one" to tell me that my "first one" seemed OK after further testing.

Thank you guys. I guess I'll just live with it. My car is probably on its last leg anyways. I'm about to break the 260K miles!

 

If the car was running well and logging good mpg prior to the traction battery replacement, then the most likely scenario would involve the traction battery not being up to par.

If you want to look for "something else", you might check the following:
1. Brakes dragging?
2. Wheel alignment off?
3. Tire pressure?
4. Assess engine performance - check cylinder compression, make sure the air filter is clean, the iridium spark plugs are in good condition, etc.

My 2004 just logged 200K miles and it still registers ~50 mpg, +/- 5% around that central value.

 

I'm also afraid that the replacement battery is at fault.

Last night I changed the spark plugs with new NGK Laser Iridium and also changed the engine air filter. I'll need to wait and see how this affected the consumption. I also got new rear struts last month and they did a 4-wheel alignment.

I'll need to look into brake dragging and cyclinder compression.

Thank you for giving me "something else" to look into. I'll report in a few days (or in a week). You guys are such a wealth of knowledge. I truly appreciate it.

 

Oh yeah I also put a "CRC 1-Tank Fuel system renew" additive when fueling up last night.

 

their website says they test the car after installation. how did that go?

 

For Battery #1 we probably drove for a mile and turned around. The "triangle of death" and PA080 were cleared and everything seemed good.

For Battery #2 we drove around for maybe 10-15 minutes. We went on back roads were we could hit 45-60 MPH. The installer wanted to be sure the battery would charge. We didn't hit too many red lights as he came at night. The installer pointed that my car was not as fast has his Prius and there was most likely something wrong with the car other than the traction battery.

 

My car is finally back to normal! I'm still not getting 50 mpg, but that's just the way I drive. I am back to the mid-40's which is what I've been getting since I bought my first Prius.

Two main factors were at play:
1) Weather. I live in the South and we had the worst heatwave since 1896! No wonder my A/C was draining my battery within minutes of stopping at a traffic light.

2) Oil level. I rarely check the oil level in my car as I am very diligent and get regular oil changes. I had the rear suspension redone in June and got an oil change then, or so I thought! I looked at the detail of my invoice last week and noticed he didn't charge me for the oil change, so that was probably not done.

My car scared me with a red oil can icon on the MFD shortly after my last post. I checked the oil level and couldn't see anything on the dipstick. I started pouring oil and put in 3.5 quarts!!! That means my car only had 0.5 quart of oil left.

I never notice my car burning oil before. My suspicion is that I also changed my catalytic converter in June, maybe my old one was so clogged that my engine had to work harder and burned oil in the process. I'm not sure if that makes sense or not, but I don't really care at this point.

I got 46 mpg going to the office the day after pouring oil in. I drove my car for about 1,500 miles since then, the MPGs are back to normal and the oil level hasn't dropped.

Thank you to all those who chimed in and assisted me.

 

3.5 quarts is all the oil the car will hold, I can't imagine the car was completely dry. Usually the low oil indicator will come on when you are around 2quarts low.

After your low oil episode, you went from 3.5 quarts of usage to zero. Something is not right