Rough engine start

Any luck to replicate at the dealer? Any success in getting to acknowledge that this is a problem? Or, just more of the usual - "It's normal readjustment of the flux capacitor..."

 

Tumbleweed,

Thanks for this advice. I had a rough start a few weeks ago after moving my car from driveway to garage in cold weather. The next morning it started rough, but since I had read your post on this before, I pressed the accelerator to the floor and the engine leveled right out.

Thanks,

Dwight

 

I had it for the first time the the other day. I had moved the car a short distance the day before just after changing the oil. When I started it the next day, it was rough and had a little blueish smoke from the exhaust. I would say it definitely appeared to be "flooded"

 

It has happened 2 times to me but since then I can't seem to replicated it (I don't really want to). The two times I had it I thought the entire engine was torn apart, that was how violent and loud it was. I am surprised the engine is still intact.

 

Just found another video like mine on YouTube!

 

Thanks for the vid, Bria. That's it! Except mine seems to be more related to temperature than inactivity. Red gets driven at least 500 miles a week. Now that it's warmed up here in Indiana, I've not heard anything put a nice whir on startup.

I've also been getting over 60 mpg (per the display - probably more like 57) by being gentle. Yup; sure seems to like the warm weather...

 

i read stuff in othere topics about a dealer telling that the MG's are finding the best position for running a cold start of ICE. but thats sounds not right.

and it seems that this is now pupping up on more gen 3's at the same periode of time?
maybe a batch gen3 from the factory with some part not good?

it does not sound right for sure but then again you dont get any code or is the prius not running good after this or stops running.

i hope toyota will adress this problem with a message that wil explain en hopefully telling us that its normal.

 

Try putting the car into Neutral when you have the problem and see if anything changes. This removed the electrical field from MG1/MG2 making them freewheel and runs the ICE at idle with no load. If this was "hogging" as they call it, then it would instantly stop in neutral.

I bought my Gen III back in Sept of 09 and haven't had this happen to me, but there was one time when the ICE seemed to be running rough for a few seconds when it first started up. (Just more vibration that usual) It went away and there was no sound accompanying it....

 

We experienced a short 3-4 second burst of bad knocking this morning and like you I had previously started, shifted the car into reverse and moved our precious Prius just a few yards about 48 hours earlier, which was the last time I was in the car. FWIW, our Prius is about 400 miles past its first oil change at 3,000 miles utilizing 4.5 quarts of Toyota 0-20W that I had previously purchased at our local dealership where the service was performed.

I didn't do anything after this knocking occurred as it smoothed out before I could make the decision to punch the ignition button. As our ambient low temperatures have remained fairly stable in the low 50's I suspect this anomaly is more likely associated with simply energizing the Prius for a brief period followed by a much longer interval before starting it up again. I wonder if this anomaly occurs because one may have inadvertently abbreviated the normal starting and warming sequence.

I intend to notify my friendly service manager tomorrow, who I've known for nearly a decade. I am somewhat surprised that with a trouble thread this lengthy we don't yet have an official explanation from Toyota....

 

I have had this problem a few times and have found it is better just to floor the throttle. It will smooth right out, and it's quicker than trying to shut it down with the power switch.

 

I started my Prius the other day after it was parked for over two weeks and I noticed when the ICE turned on, it was doing it. No sound and it was very mild, but I could feel slight "bucking" at the intervals you guys are saying you hear the knocking.

I put the car into neutral and it instantly smoothed out. Give that a try next time.

When the ICE is totally cold, the ECU starts it up and lets it run for a little while at 1280rpm. It is not applying any load at all to it. After 10-15 seconds (may vary depending on temp) it applies load by charging the batteries. You can hear the engine note change (RPM does not change.) The ECU is now warming up the ICE and Catalyst using load.

I noticed the roughness happens in the brief time before load is applied. When I shifted to neutral, it was totally smooth, but when I put it back into park, it was rough again. Then a couple seconds later it started charging the batteries and it was smooth.

I'm still trying to figure out what the difference is between neutral and park but not charging ... But the fact it all stops in neutral means it's not an engine issue and it is the ECU doing something with the electric motor.

As a side note, I am almost always driving away by the time the ICE starts up. I get into my car, put on my seatbelt, then hit start. As soon as ready comes on I'm in drive and on my way. The question is would the problem happen when under power? I will try next time.....

EDIT: I see people saying they were driving while this was happening. I'm still interested to see if neutral smooths things out for the folks who have had it happen really bad. (I've only had the very mild bucking feeling a couple of times.)

 

Yes you can hear it and feel it, pretty scary the first time it happens. Mine sound like one of the exhaust pipes or something is banging on the frame. That may not be what is happening but that's what it sounds like.

I think neutral works but I prefer flooring the throttle to using neutral because it is a little quicker (it takes a full second to go into neutral). When you floor the throttle in park it only raises the RPM by a couple of hundred but that change seems to stop it from knocking. For the last several months I have been flooring the throttle as soon as the ready light comes on which starts the engine immediately, that seems to prevent the knocking problem also.

 

I experienced the problem for the first time this afternoon.

Most of the time, when I switch the hybrid system off, the ICE is already off, and warmed up. But today, exceptionally, I moved the car in the driveway, so the ICE ran for only about 10 seconds (from cold) before I switched it off. 4 hours later, when I switched the hybrid system back on, the ICE started shaking.

 

I do this to my car all the time as I have to move it out to get my motorcycle out from behind the car and don't have any issue. Of course, I don't have the shaking problem either (or haven't yet had it) so not a good test.

 

I have experienced this problem before. It is often due to carbon build-up on the back of the intake valves. When the carbon build-up becomes too heavy. it can cause rough running at start-up because the carbon absorbs fuel, causing a lean fuel mixture. As the engine warms, the rough running disappears. Pieces of carbon can also break off and prevent the valve from closing until it is sucked into the cylinder. Pieces of carbon which fall in the cylinder can also cause a knocking noise until burned by combustion. The solution to this problem is the regular use of a fuel system cleaner gasoline additive, such as BG44K or GUMOUT REGAINE Complete Fuel System Cleaner; and, avoiding short trip driving.

 

On a brand new engine though?

 

dosen't gasoline already come with cleaner in it ?

 

Yes, carbon builds up quickly within 5,000 to 7,000 miles. When an engine is new, it can build up faster because the valves are not yet seated.

 

Advertised cleaners in gasoline are not strong enough to prevent the build-up of carbon which is caused by modern fuel induction systems and oxegenated gasolines. This is a common problem, preventable by simply adding an inexpensive fuel system cleaner ($5-8.00) to the tank every 5,000 to 7,000 miles. If the carbon is neglected and allowed to build up excessively, it then has to be removed by an expensive process that repair shops love to sell for $150 -$250. In the meantime, your car will run poorly and inefficiently resulting in lower mpg, higher emissions and the likelyhood that when you take it in for service it will be misdiagnosed by an incompetent or unscrupulous technician who will sell you something you don't need, Not to mention, all the time and effort you waste trying to diagnose a nonproblem. Its really just a fact of life maintenance reality for modern cars, hybrid or not.

 

It's hard for me to buy the theory of "all modern cars need regular gas cleaner treatments". I have at least one counterexample and I imagine there are many others. During the warmer seasons I regularly move my car from one spot in the parking lot to another in the middle of the day in order to keep the car in the shade as much as possible. The gas engine would be on for a very short time, maybe 30 seconds. I have never experienced rough start of the car at the end of the day.

There may be something peculiar about the gen 3 Prius engine that we haven't figured out yet.