Hi Folks, I have a problem that baffles me. At a certain point during my commute is a stop light entering the city limits. It is after 17.3 miles of non stop highway driving. 90% of the time I hit the light red. I have tried several tactics from quickly getting up to 35mph speed limit to being behind a loaded semi driving very slowly getting up to 35mph. Sometime during getting up to speed, the ice kicks in to assist (why, I don't know, it is a descent) and will not shut off until I either reach work 4 miles across town and I put the car in park, or while I am stopped at one of the 9 stop lights, I put the car into park. If I put the car into park while at a stop light, There are slight inclines with very long descents so I can drive the rest of the way with the ICE off. At all the other stop lights I can take off without the ice ever kicking in. In the rare case it does kick in, it shuts right back once I let off the accelerator. What gives????
What is your coolant temp when the engine refuses to shut off? I've seen instances of odd behavior when coolant temps are high.
How many GREEN bars are showing on the MFD? You could be just burning off battery charge as the car thinks it needs to make room in the HV pack for the next highway sprint and long off ramp re-gen. I have this same condition when I get off the interstate in Al and down an off ramp to a red stop light.
The reason is, because you are not in stage S4 (see attached). Even though your ICE is warmed up, you need to do the "idle dance" which means coming to a stop for 7-10 seconds with the ICE on after the ICE coolant temp reaches 73 C. Read the attached very carefully and over and over.
Hi STGC, I'm looking for the links by Grahm on gen 1's shown in your link "5 stages"...tried the Priuschschat search several ways, can you please advise. Thanks, Robert
Links by Grahm???, I'm not familiar with it but I do know that the Gen 1 goes thru the same stages. It just has some differences if the AC is on (because of the belt driven AC compressor). It virtually operates the same.
It doesn't and it sounds like that's the problem he's having. If you were on the highway and you don't come to a stop and go to mode S4 before that, it will never go to S4 until you come to complete stop for 7 to 10 seconds after you get off the freeway
The reason I ask, is on the highway, sometimes I see lower MPG after a stop for gasoline. Is that because I am stuck in Stage 3b? Are others trying to get into Stage 4 before they get back onto highway?
Your mpg on the highway should not be affected by stage 3b or 4 (unless you hit stop and go traffic and stop with the ICE off or, with it on for less than 7-10 seconds. This is a very likely scenario in your neck of the woods). My personal practice is to try to get it to stage 4 ASAP. A driver who goes straight to the freeway and stays there for a while will likely have no opportunity to reach stage 4 until exiting the freeway. What I do to ensure stage 4 is, once I come to a stop if the ICE is off, I put my lef foot on the brake and force it to start by pressing the gas with my right foot. If it is in S4, it will start then shut off right away. If it is in 3b but at the correct operating temp, it will continue to run for 7-10 seconds then shut off. Either way, this lets you know you are in S4. If its not at the correct temp, it will run until it gets to the correct temp and then shut off. If when you come to a stop and the ICE is on, you need only stop for 7-10 seconds (until the ICE shuts off). Knowing all this info really helps you operate the Gen II in the most efficient manner and will improve your average mpg.
There are some reports that being in stage 4 may slightly improve your fuel economy, even at speeds where the lack of gliding due to stage 3a isn't an issue. Let me explain. It is thought that the very purpose of the "idle dance" is to allow the Prius to do a quick sanity check on the oxygen (exhaust) sensors prior to switching the engine control from open loop to full closed loop operation. How much this change of mode effects fuel economy may depend on just how well in calibration are the sensors and fuel injectors in the first place, but various people have report small improvements (other than just gliding) after allowing the "idle dance". NinnJinn, try to definitively rule out (or in) whether this is a simple stage3/stage4 issue by ensuring that you reach a stable speed of at least 36 or 37 MPH (for at least several seconds) before you quickly remove the go pedal input and glide. From under 35 you definitely wont glide in stage 3.
Hi Ninnjin, I just reread your start to this thread, and I think I see something in it...you are having a geographical problem with your Prius. You are describing a problem that you have at one stoplight that you are not having at all the other stoplights. You have gotten good input from some members on SOC, stage, and coolant temp. If those 3 factors are in line and you rule them out, I suggest EMF. Any power lines overhead, or a big transformer nearby? camera or other sensor on that light? My Saturn used to downshift 4-3 and stay there sometimes, till I flicked the key off and on, then would upshift to 4 again. Even changing the ECU didn't help. Then I recognized that it was happening in the same place every time! I suggest you hum through that light when you are sure stage, SOC and temp are ready, and see if the ICE still kicks in. Sadly, if EMF is the problem, the only cure is wrapping your car completely in several layers of tinfoil!
