2002 Prius 138k: Loud rumble (from ICE?) when started

Just an idea:
My 2002 was having trouble a few weeks ago - 95,000 miles, ICE rumbling, and more problems after restarting 10-15 mins after shopping. The difference was that most of the time the car would stop itself 15 seconds after start up(most of the time) with error messages.

Turned out my throttle plate/throttle body needed cleaning - really bad. Also cleaned the dirty black MAF sensor. I went to Auto Zone and purchased "Throttle Body Cleaner", and also purchased "MAF Sensor Cleaner" (I think they carried only one type of each, shelved in the same general area)

Check here(thanks Bob Wilson):
Cleaning Prius Throttle

and here(may or may not help):
http://priuschat.com/forums/generat...-toyota-has-extended-warranty-some-codes.html

Jayman has great pictures of how to remove the MAF sensor first(before cleaning the throttle body):
You'll need a very short phillips screwdriver - 2 screws marked "B".
http://priuschat.com/forums/gen-ii-...roubleshooting/57617-cleaning-maf-sensor.html

The sprays were around $10 each, maybe less. Keep the appropriate spray on the appropriate parts. Even when the Throttle Body cleaner says safe for MAF sensors, it wasn't worth the risk for me.

Also:
I had tried 3rd party spark plugs ONCE(about 60,000 miles). I then pulled those out after they caused unusual shuderring. Replaced with OEM matching (ordered/purchased NGK Iridium spark plugs at one of the auto parts stores-NOT purchased from Toyota, but the exact same plugs) The unusual shuddering went away with the new plugs.

 

Sorry to hear this:

We need to determine if the engine is involved or not. Could you drive the car for say 15 minutes or so and then go to a shallow hill without traffic, say a neighborhood hill:

1. Stop at the top where you can roll by releasing the brake yet not be a traffic hazard.
2. Wait for engine to stop.
3. Shift into "N" and start rolling down the hill . . . listen for the rumble.

If the car rolls without the rumble, it suggests the transmission is not involved.

Bob Wilson

 

I also wouldn't rule out a lot oil in the intake manifold.. I made a video on how to check for and fix this problem:

 

You will have to drain some oil out or the problem will continue. as you saw in my video all you need to do is loosen that screw and let some drain out into a pan, put the screw back, wait a minute, then check the oil level again. It may take multiple releases to get enough out.. Don't worry, should you let too much out you can always add more oil back into the engine from a bottle from Wal-Mart or something.

 

I like the video ... very helpful. Just some minor thoughts:

• point out the clean surface of the throttle plate edge and look for accumulated stuff on the smooth throttle throat. It should be shiny and smooth without any ridges.
• possibly add a segment on MAF cleaning?

My rule of thumb is to clean the throttle area in the Fall, before the cold weather. For good measure, I add a can of injector cleaner in the tank too.

These are just minor suggestions as there is a lot of good in this video and I especially like the way it goes step-by-step. Well done!

Bob Wilson

 

Was the 'rumble' somewhat like an engine running rough?

Did you feel the car shaking or was it more noise?

How long did it last . . . seconds, 10s seconds, longer?

The reason I ask is 138,000 miles is about the limit of the sparkplugs. If they are starting to get marginal, they too could cause intermittent grief.

Bob Wilson

 

I hope you will consider visting a Toyota shop (and probably paying) for diagnostic trouble codes if any. If there are misfire codes, we need to think about plugs, ignitors and injectors.

 

The "top notch" of the dipstick (the second mark from the end of the dipstick) is the FULL mark.

An oil level that reaches that mark does not indicate overfill.

 

The rule of thumb:

• error codes light indicator lights - upon first occurance
• 3 restarts clear error code lights - the codes will be remembered by the controller
• 12 V power disconnect - disconnecting the 12 V battery clears the codes as well as accumulated fuel trim. Loss of the fuel trim can cause low mileage until the car relearns the trims

As for scanners, there are multiple Electronic Control Units (ECUs) that operate the car. Of these, the more important ones:

1. HV ECU - hybrid vehicle ECU manages the car as a system including signals that operate the inverter and transmission. The accelerator pedal inputs feed to the HV ECU which in turn provides power as needed.
2. Engine ECU - keeps the engine happy and responds to HV ECU to supply power as needed.
3. Battery ECU - keeps the 38, 6-cell, battery modules in the traction battery happy and healthy. The 38 battery modules are grouped into 19 pairs.
4. ABS ECU - Antilock Brake System ECU handles the sophisticated braking system. There is hydraulic backup but for most braking, it is 'by wire.'
5. EMPS - Electronic Motor-assisted Power Steering uses torque sensors to power an electronic motor to provide power assistance
6. Body ECU - the lights and power windows and locks
7. ABS ECU - hopefully never used but if used, saves lives

The problem is I've only found one 'over the counter' OBD scanner that even claimed the ability to find the other controllers but I couldn't get it to plug in. Furthermore, the OBD in our NHW11 uses ISO-9141 protocol. So far, we've only found two scanners that come close:

• Auto Enginuity - somewhat buggy, I'm still testing but it acts as if there is a BAUD rate mismatch leading to maddening data results. Also, it can induce false error codes unless started in a way not documented (nor supported) by Auto Enginuity.
• Graham Miniscanner - no long in manufacture, this handy scanner knows the HV, engine and battery ECU and does an amazing job of reading the last three, stored codes; clearing them; and over 50 engineering data points. A little less than 300 were made and I buy them whenever someone has them available and rent them out to folks with 'project' cars. A 'lending library' if you wish.
• OBD two-code flash - there is a little known technique that uses an OBD connector and two push buttons to trigger 'flash' of the lower, two digits of error codes. I have the parts and plan to test it. No engineering data but enough diagnostic codes to fault isolate some failures.

Oh, if I haven't said it yet, Welcome to Club Prius! <GRINS>

Bob Wilson

 

You would think that would be the case. But that has not been my experience, nor that of other toyota technicians I've spoken too. If the oil is filled up to exactly the second notch, then it will start having problems with oil getting sucked into the intake. You really need to try to get it noticeably below that second mark.

 

I do indeed think that is the case.

While the Prius engine can be overfilled with oil just like any other engine, it does not need to be underfilled to operate correctly.

That's not true. But don't take my word for it. Try it the next time you need an oil change. Fill it with 3.9 quarts, just like Toyota says you should. Heck, fill it with four quarts of oil, and see what happens.

There is something happening in your video that may in some cases alleviate engine performance issues, but it's not what you think it is.

By the way, if the Prius engine is overfilled with engine oil enough to pool oil in the intake manifold, you will need to remove the throttle body to adequately clean out the excess oil. You can't do a complete job through the throttle bore.

 

To be "under filled" it would have to be below the bottom notch on the dipstick. I haven't suggested that is the case. However, when oil is at that top notch, my prius most definitely will suck oil up there. In fact, in the video I made oil was at the top notch and you saw the amount of oil that pooled into the intake.

Now, I also realize the "proper" method for clearing this out does require removing the throttle body and this is even what Toyota's official procedure involves. However, this never happens at the dealership. Just like many other procedures, technicians are not going to take the time to do that because they make pennies as technicians and it would take too long to do the proper procedure so they do what I showed in the video and it tends to work good enough. In fact, many technicians won't bother to clean it out at all. If you remove enough oil from the engine, as long as it will start it will eventually drain out of there in time.

I had the opportunity to talk to a Toyota field specialist one time who was in the area. These are the guys that are supposed be the real experts who go out to dealerships to solve problems when the local guys can't figure it out. I asked him why the Prius has this problem where other cars don't (when the oil is overfilled.) he said it was because of the high RPM at which the engine is started, causes a bigger vacuum and pulls the oil up there. I don't fully understand how that happens, but that is what he said.

 

One of the first suggestions other owners offered was the optimum oil level is 3/4ths between the marks. I drained about a quart to reach that point, a Fort Worth dealer sold the car, and I gained +4 MPG the next week. Between the marks is the sweet-spot.

Bob Wilson

 

I haven't stated that you suggested that. However, you are using your own personal definition of "underfilled". I'm using the definition that was created by the company that designed and built the engine itself. Your hypothesis assumes:

a) Toyota somehow failed to figure out the correct oil level for the engine that they designed and built for the Gen 1 Prius.

b) Assuming that (a) is true, Toyota has yet to correct the issue, even though it would have created years of warranty costs for the company.

What have you observed with your own eyes that supports this hypothesis?

A bit, but that's normal. A correctly filled crankcase, as defined by Toyota (3.9 quarts, to the second mark on the dipstick) will not create running problems, much less a no-start, as you have claimed.

Keep in mind that with the most common crankcase capacity for a four-cylinder engine being four quarts, the average technician will dump four quarts in an engine that calls for 3.9 quarts, overfilling the crankcase by 0.1 quarts. I would wager that easily 95% of Gen 1 Prius oil changes are carried out in such a manner. Why aren't the cars dropping like flies?

It's hard to say for sure, but I saw what appeared to be a light coating of oil which I consider to be normal. I definitely didn't see oil "pooled" in the intake, in the manner that I have seen when the crankcase has been overfilled.

What is the repair manual page or technical service bulletin that describes this procedure?

I disagree. There are a lot of dealerships in the world. How would you know this?

Why not? They are normally paid by the job. If the job requires more labor, the price of that labor goes up.

Most competent technicians have decent paychecks, as well they should.

Again, most technicians are paid by the job. If the job requires more labor, the price of that labor goes up.

No. If oil pools in the intake manifold enough to cause a running problem, it extends beyond either side of the throttle bore by at least several inches. You simply cannot access all of the oil without removing the throttle body.

They are supposed to be. Some are more knowledgeable than others.

Almost all hybrids start their engines at high RPM, yet they don't have this problem. The Gen II Prius engine is similar to the Gen I Prius engine, yet it doesn't have this problem. Why not?

I think we're getting at the heart of things here. In my opinion, it is fair to say that if someone is repeating hearsay which they admittedly do not understand, then they are perhaps not equipped to determine whether or not that hearsay ever had any truth to it.

Keep in mind that I am not trying to convince you that your methods are wrong. I am posting for the benefit of the person who started this thread, and has a problem to solve. That person deserves accurate information.

I think many enthusiasts are attracted to tales of special procedures that improve upon the care recommended by the automaker. No doubt some of them will "adjust" the oil volume in their vehicle's engine to less than that recommended by the manufacturer, and when their vehicle does not suffer running problems as a result, announce that it "proves" that the modification is indeed an improvement. Naturally, it proves no such thing.

But if you really want to establish that a correctly filled crankcase, as defined by Toyota, somehow causes performance issues and even no-starts, you will need to:

(a) find vehicles with such issues

(b) of those vehicles, find vehicles with correctly filled crankcases

(c) isolate the oil level as the cause of the problem

(d) show how the oil level caused the problem

(e) ensure that no other repairs are made

(f) show that reducing the oil level, and nothing else, solved the problem

Your video does not do this.