'99 Outback 2.5L 130k idles at about 250rpm

 

BACKGROUND: It has ran rough since I bought it at 70k. The previous owner had tried to get it fixed a number of times, and I had it checked out before I bought it. They all concluded that "that is just how it is." I was under the impression that the Boxer engine allowed it to run even smoother that a V engine.

 

SYMPTOMS: Rough running is most apparent when the tranny is in D at a stoplight, although I am not sure if it is just because my foot is on the brake so I can feel it more. It is pretty rough, and worsening, to the point where I often put it in neutral when waiting at a light. It runs mediocre at above idle rpms. No check engine light.

 

QUESTION: What can I check first, before a mechanic tells me I need expensive internal engine repair?

 

MAINT. REC'D.-

Timing belt has 60k on it

New wires, plugs have 10-15k

PCV, fuel filt., air filt. have 10k

 

 

Thanks,

Andrew

that idle speed is too low should be in the area of 6-700 rpm in gear if auto

Fuel Injectors. Motor Mounts. Tranny Mounts. Go ahead and put a new air filter in. Get your tranny fluids changed and maybe your oil too?

 

Edit: Are you sure the wires are all going to the correct places?

The mechanic did my wires, as they were under warranty. I'll check them, but it ran rough well before that too. 10k on tranny fluid and about 200mi on fresh oil.

 

Do I really have to jack the engine up to check the motor mounts, or is there a simpler way?

 

Thanks

that idle speed is too low should be in the area of 6-700 rpm in gear if auto

 

I agree, you should bring your idle speed to specs, and then your plug cables, spark plugs will tell you a lot about an engine!

1. How do you figure its 250? is it between zero and the first mark, which is 500?

2. Did you search? Here's a useful tread: Idle dips to 275?

that idle speed is too low should be in the area of 6-700 rpm in gear if auto

 

Isn't the idle speed controlled only by ECU? I just realized that it's an outback but my 90 legacy cannot be adjusted. I read in the haynes book that the ECU controlls timing and idle speed and neither can be manually adjusted. I would assume it's the same with a newer outback.

 

Check compression? Injectors? No ECU codes?

Thanks. I am going to work on getting the idle up to spec... according to my Haynes (which is actually for a '98) it CAN be adjusted on cars following a VECI instructions sticker under the hood, but requires a special handheld tach that pulls an accurate RPM from a harness under the hood.

 

I will also look into getting a vacuum gauge.

 

Has anyone set their idle using this method? Are these readers expensive?

 

Dmanaenk- On my '99 the tach is graduated in 200 RPM increments, so assuming it is accurate, it reads slightly above the first tick which is about 250--- regardless, it is just really low.

 

Dmanaenk- On my '99 the tach is graduated in 200 RPM increments, so assuming it is accurate, it reads slightly above the first tick which is about 250--- regardless, it is just really low.

 

Hm, all '99 clusters I have seen look exactly like this one:

I don't see any 250 tick.

Could it coincide with timing belt replacement? In other words - off by a tooth. Previous owner may know this??

 

Just a thought. Only way to check is to remove it and put it back on.

 

rd

Yeah, thats the one. There isn't a tick for 250, but a tick for 200: the first one. They go 200, 400, 600, 800, and then the big 1000 rpm mark. Mine is just above the 200 one....

 

I would estimate it fluctuates between 250 and 300 rpms, according to my tach which may not be accurate. But the number isn't important... it shakes the whole car because it is too low.

I fear timing belt problems... if that thing comes off, I am getting the whole shebang (pump, seals..etc.) because it is due within 30k. It very well may be, however, as I doubt the mechanics would go to such lengths to diagnose a low/rough idle.

 

If simpler fixes dont cut it, that is probably where I'll look.

That first mark is 500 rpm, if your at the second or third mark your idling at 600-700 rpm. Not far from factory spec. I wouldn't mess with the idle except for maybe cleaning your IAC.

First tick is 500.

Since it runs bad, not only at idle - I'd say its not idle-related issue.

Check timing.

Ahhh... I see. My bad. They should have one of those little zig zags like the ones they make you use on graphs in math class. I assumed the scale started at zero.

 

Thanks, I may sack up and get the timing looked at.

There are several threads on this problem. Sorry to say, there is no sure thing solution.

I think your idle is OK at 600-700 rpm. I doubt it would run at 300.

I doubt it is the tranny fluid since yours was done recently.

A skipped crank tooth would idle poorly when in neutral as well as in gear. You would be down on power and fuel consumption would be relatively poor.

 

This sure is an annoying problem! Mine is more severe when the car is cold, but it never goes away completely.

I am going to swap engine mounts to eliminate this possibility, but I am not hopeful.

I will be interested to see if that makes a difference. I have often wondered if changing them would help.

the IAC controls the idle, this is adjustable well its is on both my 92 models the iac can only adjust so far up and down so you can set its starting point

I had the dealer swap tranny filters and flush the coolant and replace with OEM stuff.

No difference in the vibration in gear.

I spoke to the service manager. He suggested it could be the engine mounts.

He said to try loosening the mounts and let the engine settle in, then retighted. There may be some tension causing the vibration. If not that then swap the mounts.