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Discussion Starter #1
I own a 99 outback wagon MT 2.5 with 190k miles. I have owned it for 2 years now and there hasn't been a need for many repairs. New plugs and wires (6 mo ago), replaced radiator hoses, alternator, and thermostat is all.

I feel like my cruising RPMs are really high, at 65mph I am revving at 3000 and at 70 mph I am at 3300. From what i was reading it seemed to be normal, but then I drove the same car, but an automatic transmission. At 65 is was only around 2500 rpm and at 70 it was at 2800.

Is there a reason a AT would cruise at lower RPMs than a MT? I feel like that car had more "get up" than mine. Please feed me some places i might start.

Catalytic Converter?
Fuel Filter?
Timing belt issues?
Spark plugs and wires?
Coil?

In addition, when I get going about 80, the CEL starts to blink and it reads a cylinder 3/4 misfire, but I just changed the plugs and wires, I need some help. Thanks.
 

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They might appear to be the same car but they're not. The 99 Outback with 2.5 engine and manual transmission has a 5th gear ratio of 0.871 and a final gear ratio of 4.111 for an overall ratio of 3.57.

The 99 Outback with 2.5 engine and automatic transmission has a 4th gear ratio of 0.694 and a final ratio of 4.444 for an overall ratio of 3.08. This means that with the same size tires, and the torque converter locked, the engine in the automatic will turn about 14% less at the same speed. If the manual car is running at 3000 rpm at 65, the automatic would run at about 2580 rpm.

It's not unusual for automatic-equipped cars to have a lower overall ratio that's lower than the manual. This is because of the use of a torque converter with the automatic.

Also, in that year the regular Legacy (i.e., not Outback) had different transmission specs, as did the cars that might have had the 2.2 engine installed. So even if they seem to be the same, they aren't necessarily.
 

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3 2001 Outbacks, 2 AT, 1 MT. 1 2006 Outback AT, 2000 Outback AT, 2008 Outback Sport MT
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I have both an auto and mt version of the '01 and at 65 mph my auto is at around 2500 rpm, while the mt is at 3000 rpm. I just think it's the way it's geared.

JP
 

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In addition, when I get going about 80, the CEL starts to blink and it reads a cylinder 3/4 misfire, but I just changed the plugs and wires, I need some help.
Was the misfire apparent before the plugs and wires were replaced, or only after? What brand of plugs and wires did you install?

Missing on 3 and 4 could be due to a failing coil or igniter. The same parts of the coil pack and of the igniter circuit are used for the spark plugs at cylinders 3 and 4. But this is only one possibility.
 

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Discussion Starter #5
plain OM,

I had the CEL, then I changed the wires and plugs, (NGK plugs, and i don't remember the brand of wires i picked up,) and I took it on a trip and the code came up again. It could be the coil or igniter. Is there somewhere I can get these tested? If so, is it an easy DIY fix?
 

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I'm not aware of any way to test the coil and igniter especially when there isn't a clear, permanent failure such as an open or shorted circuit.

Coil and igniter should be relatively easy to replace but the cost for new parts is not insignificant. Shop around and see what on-line parts suppliers, such as subaruonlineparts.com have.

The coil on your 99 should be up on top of the intake manifold -- where the wires from the spark plugs end. The spark plug wires come out (you've done this when the wires were replaced), there's a connector to pull out, and then three or four long screws to remove the coil assembly.

The igniter involves just a connector and a screw or two holding it in place.

Might also want to look at other threads related to coils and igniters. Example: see this thread.
 

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Discussion Starter #7
Thanks for the tip. I went and had it coded yesterday and it came up with a 3/4 misfire and a crankshaft position sensor. The sensor seems easy enough to switch out. What sort of performance issues could be causes by a 3/4 misfire and a crankshaft sensor?

Also, I dont want to cross too many lines but, my brother has a 98 forester 2.5 MT, and it has the same engine but it has lower RPMs at cruising speeds as well. Another gear ratio difference between the outback and forester? I just feel like my mpgs are pretty crappy and wondering if the high RPMs, 3/4 misfire or the crankshaft could be causing it.

Sorry for the essay. Thanks.
 

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While I'm no expert in this area, I would think that a problematic crankshaft position sensor could well cause misfires if the engine control module isn't being provided accurate information about the crankshaft. In light of this newly identified issue, that might be where you should focus.

It might be an idea to add a post here with the actual diagnostic trouble code, or codes, that identify the crankshaft position sensor problem. Perhaps others will have more information about what these particular codes mean, and the best way to deal with them. (I'd suggest starting a new thread about this problem alone -- the title of the current thread deals with rpm, and might not attract interest related to misfires.)

In regard to the Forester comparison, I don't have specs for the 98 Forester, but in 1999 the overall ratio for the MT Forester is 3.206, which compared to your 3.57, would make the Forester's rpm about 11% less, all other things, including tire size, being equal.

I believe your 99 Outback came with 205/70/15 tires. According to this calculator, that size tire would, on average, turn 790.90 revs/mi. At 60 mph, it would turn 790.9 revs per minute. The overall gear ratio on your car is 3.57, so the engine would be turning 2824 rpm. At 70 mph it would turn 1.1666 times that, or 3295 rpm, which is pretty well what you reported (3300). Your car's rpm is correct.

If the engine is misfiring, it could well be using more fuel to move the car the same distance, but the rpm would be the same at any particular speed even if the engine were running 100%.
 
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