[Sooby07]

I have an 07 automatic with 73,000 mi. Over the past couple of days, when I start cold it immediately revs to 6,500 rpms and settles back down to 1,000 rpms which is normal cold idle. The rev is so quick that if you didn't hear it, you'd never know it was happening. This only happens when the engine is cold - 4+ hours of sitting.

I don't like this intense strain on cold start ups as I plan on having this car for a very long time. Is this the cold start module or something else entirely?

 

[cardoc]

I have an 07 automatic with 73,000 mi. Over the past couple of days, when I start cold it immediately revs to 6,500 rpms and settles back down to 1,000 rpms which is normal cold idle. The rev is so quick that if you didn't hear it, you'd never know it was happening. This only happens when the engine is cold - 4+ hours of sitting.

I don't like this intense strain on cold start ups as I plan on having this car for a very long time. Is this the cold start module or something else entirely?

Is it an Outback Limited or an LL Bean? You have 2.5 as the engine, then LL Bean. No 2.5 in the Bean.

 

[jp1203]

Is it an Outback Limited or an LL Bean? You have 2.5 as the engine, then LL Bean. No 2.5 in the Bean.

Actually, for 2007 and 2008 there was a 2.5 Bean: 2007 Subaru Outback research site: prices, options, what's new this year, colors, specs, photos and more

Open the hood. Does the engine cover say "Subaru Boxer H6"? That's the easiest way to tell on a 3rd gen, since not every H6 will have a 3.0R badge on the tailgate.

 

[Sooby07]

It's a 2.5 with the Bean upgrade package, not the 3.0 Bean.

 

[cardoc]

Never ran across one.

NUMBER: 11-84-07
DATE: 10/15/07

APPLICABILITY:
2005 and Later Naturally Aspirated
(Non-Turbo) PZEV (Partial Zero Emission) models

SUBJECT:
PZEV Idle Fluctuation after Cold Start

INTRODUCTION

This bulletin is for informational purposes only.

If you encounter a customer complaint about an idle fluctuation ("hunting") during cold starts which generally last about 20 to 30 seconds the cause is a combination of factors.

Some of these are:

^ Fuel blends

^ Percentage of Ethanol content of the fuel being used

^ Temperature

^ Narrow operating range of the Air Fuel Ratio Sensor The main cause of this idle fluctuation is fuel related and not the vehicle.


PZEV engines are designed to run on fuel blended for distribution within certain areas of the U.S. (such as the state of California). Fuels available in other markets, that may have adopted California emission standards, may be a slightly different blend. If you live in any other state than California, your vehicle will operate on gasoline meeting Federal specifications. However, PZLV vehicles may experience this issue especially during the summer months when summer blend fuels are distributed. There is no effect on vehicle emissions, and no short or long term damage will occur due to this issue.

The condition may be reduced or eliminated by changing to a fuel that contains a lesser percentage or no Ethanol Also, a light throttle application while the vehicle is exhibiting this condition will stabilize the idle. As we move towards cooler weather many areas of the country will be changing to a winter blend of fuel which may also alleviate the condition

If this condition is confirmed, no repair attempts should be performed beyond confirmation and checking all other systems are operating within design parameters.

 

[selenski]

So Sooby07, I guess these comments have solved your problem with 6500 rpm at cold start. Your car should now last many years. I hope mine will too.
Joe

 

[Sooby07]

Never ran across one.

NUMBER: 11-84-07
DATE: 10/15/07

APPLICABILITY:
2005 and Later Naturally Aspirated
(Non-Turbo) PZEV (Partial Zero Emission) models

SUBJECT:
PZEV Idle Fluctuation after Cold Start

INTRODUCTION

This bulletin is for informational purposes only.

If you encounter a customer complaint about an idle fluctuation ("hunting") during cold starts which generally last about 20 to 30 seconds the cause is a combination of factors.

Some of these are:

^ Fuel blends

^ Percentage of Ethanol content of the fuel being used

^ Temperature

^ Narrow operating range of the Air Fuel Ratio Sensor The main cause of this idle fluctuation is fuel related and not the vehicle.


PZEV engines are designed to run on fuel blended for distribution within certain areas of the U.S. (such as the state of California). Fuels available in other markets, that may have adopted California emission standards, may be a slightly different blend. If you live in any other state than California, your vehicle will operate on gasoline meeting Federal specifications. However, PZLV vehicles may experience this issue especially during the summer months when summer blend fuels are distributed. There is no effect on vehicle emissions, and no short or long term damage will occur due to this issue.

The condition may be reduced or eliminated by changing to a fuel that contains a lesser percentage or no Ethanol Also, a light throttle application while the vehicle is exhibiting this condition will stabilize the idle. As we move towards cooler weather many areas of the country will be changing to a winter blend of fuel which may also alleviate the condition

If this condition is confirmed, no repair attempts should be performed beyond confirmation and checking all other systems are operating within design parameters.

Were all 07's PZEV even if it's not specified on any of the vehicle literature?

The surge to 6,500 lasts less than a second and returns to what is considered a normal, cold idle. Tops out right at red line - is there an idle limiter keeping it from going higher? This seems a little different from hunting or a simple high idle which I've experienced in all my other Subarus.

 

[cardoc]

Try this. If it doesn't work contact dealer service and ask if they've come across it. I haven't, but we don't get long cold days here.

Disconnect the battery for a minute and reconnect. This clears the ECM. On the next start up, the ECM will relearn idle position. Don't touch the accelerator pedal. The electronic throttle body also controls idle by voltage sent from the ECM in the same way it controls the throttle blade position when driving.

 

[Sooby07]

Try this. If it doesn't work contact dealer service and ask if they've come across it. I haven't, but we don't get long cold days here.

Disconnect the battery for a minute and reconnect. This clears the ECM. On the next start up, the ECM will relearn idle position. Don't touch the accelerator pedal. The electronic throttle body also controls idle by voltage sent from the ECM in the same way it controls the throttle blade position when driving.

Thanks for the tip. I actually just sent it to the dealer for the software update and they are hoping that takes care of it. Couple of notes though - the needle on the tachometer swings to max when you turn the key. Visually, I was paying more attention to this than I had before simply because I was hearing something different from the engine. I still feel the rpm's are going much higher than necessary/normal during cold starts but not as high as I feared.

I had been putting off the software update because we moved and the dealer is now 50 miles away. Thanks to AAA, she took a free ride on a rollback for the software update and will be checked for any start-up shenanigans tomorrow morning.

 

[John E Davies]

I can' comment much on your problem, other than to say that if the engine truly is hitting redline at startup, there has already been some serious damage.

OTH, I bet it is really more like 2000 or 3000 rpm, which is bad enough IMHO.

Can you rent or borrow a tool like this? That will tell you the true max rpm.

Digital Photo Sensor Tachometer

If the engine continues to rev freely at startup in spite of everything, you should switch to synthetic oil for the much better cold start protection.

Good luck.