Rough Idle - Loss of Power from Headlights / A/C?? -- SOLVED!

[CroMath]

Originally Posted by ravenuer

Not familiar with the 85 octane fuel. Does your manual mention anything about it? Otherwise, I'd definitely put more miles on it and see what happens.

Me neither - it's nice to learn something new.

At any rate, here's what I saw on Wikipedia (search term = octane rating)

United States: in the US octane rating is displayed in AKI. In the Rocky Mountain (high elevation) states, 85 AKI (90 RON) is the minimum octane, and 91 AKI (95 RON) is the maximum octane available in fuel. The reason for this is that in higher-elevation areas, a typical naturally aspirated engine draws in less air mass per cycle because of the reduced density of the atmosphere. This directly translates to less fuel and reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill a carbureted car that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine. A disadvantage to this strategy is that most turbocharged vehicles are unable to produce full power, even when using the "premium" 91 AKI fuel. In some east coast states, up to 94 AKI (98 RON) is available.As of January, 2011, over 40 states and a total of over 2500 stations offer ethanol-based E-85 fuel with 105 AKI. Often, filling stations near US racing tracks will offer higher octane levels such as 100 AKI.

I would be inclined to think you've got a bad tank of gas - maybe a fresh fill at a different station would help.

[ColoradoRav]

Thanks all for the input. This seems like a great forum.

I did do enough research a while back to see that the RAV here in Colorado only needs 85 octane. CroMath, your article is correct, here our gas choices are 85, 87 and 91 at most gas stations.

So on the drive home tonight I did not notice the rough idle. Either it's gone or I was too much in a hurry to notice.

Let's hope it stays away. Now, time to move on to more important things like what I am going to do first to our RAV!e

[ColoradoRav]

I have an appointment with the dealer on Friday so I'll let you all know what I find out. After getting to know the situation better here are the details:

- seems to happen almost always at night on the way home from work but not in the morning
- when the engine is idling at 700 rpm it is perfectly smooth
- the shaking is felt when the idle jumps up to about 1000 rpm then it will drop to 700 and be smooth then back to 1000

We'll see what the dealer says Friday but he said he has never heard of this with the Rav.

Any advice or words of Wisdom? I wonder if my altitude had any role?

[ColoradoRav]

Got the Rav back from the dealer. They said everything is normal and the rough idle must be from me selecting an option that requires A/C.

Tonight, on the way home, it did it again, with no a/c on. I pulled over and messed with things until I finally found exactly what is causing the issue. The headlights!? When I turn them off the idle drops to 700 and is smooth. When I turn them on the idle jumps to 1000 and the idle is a little rough. This explains why it's only happening at night. Duh. I feel dumb for not trying that sooner. The dealership said he has not heard of that.

Do your Ravs do that when you turn on headlights? (might only be the I4). Does this seem normal? I am use to driving my 6 cylinder so this is new territory for me. Or maybe my Rav has an issue...

[Shep426]

My 2012 I4 has a very slight noticeable change in idle quality with any load on the engine, I do not have a 300 rpm increase in idle speed with the headlites on though.

[ColoradoRav]

Ok went to dealership #2 (next to my work and is way better by the way) and the answer to the rough idle is...well...that it's perfectly normal. They, just like the first dealership said it was running exactly as it should. Here is the difference between them and the 1st dealership. He said, "pick out any new RAV4 on the lot, and take it for a drive to compare, we did."

So I found my exact car, silver, I4, base and you know what, it was almost the same as mine. The only difference is that its idle was even rougher. So, I can finally relax. Finally! Now I know that it's not just my car. I am at peace knowing this.

Again, now time to think about fun things to do with the Rav (and to remind myself to get the V6 next time so this is not an issue).

Thanks again for putting up with my questions!

[RTexasF]

If you want the V-6 next time you'll have to buy it used. It is gone for 2013 models.

[Shep426]

Originally Posted by ColoradoRav

Ok went to dealership #2 (next to my work and is way better by the way) and the answer to the rough idle is...well...that it's perfectly normal. They, just like the first dealership said it was running exactly as it should. Here is the difference between them and the 1st dealership. He said, "pick out any new RAV4 on the lot, and take it for a drive to compare, we did."

So I found my exact car, silver, I4, base and you know what, it was almost the same as mine. The only difference is that its idle was even rougher. So, I can finally relax. Finally! Now I know that it's not just my car. I am at peace knowing this.

Again, now time to think about fun things to do with the Rav (and to remind myself to get the V6 next time so this is not an issue).

Thanks again for putting up with my questions!

Yup, like I said same as mine.

[ravenuer]

Originally Posted by RTexasF

If you want the V-6 next time you'll have to buy it used. It is gone for 2013 models.

sniff.....