Full Throttle at low RPM, or High RPM and low throttle
 

so I just got in from a night of driving my mom's 1997 Subaru legacy (not outback) wagon around with the fuel needle just above empty. It's a 5 speed, and has god knows how manny censors and such dead in the engine, but at just under 200k miles, I'm lucky it's running.

Anyways, I know the IDEAL thing to do is to barely tap the gas pedal and shift as low as you can without making the engine knock/ping or stall. However, because this car has lost alot of horsepower over the years, to the point where in 5th gear it takes about 30 seconds to go from 60 to 65 and it tops out around 75, and the fact that around here you kind of have to be able to zip out into traffic, I'm wondering, which is the lesser of two evils? Shifting at a higher RPM but not putting your foot all the way down, or Jamming it to the floor and shifting at around 2,000 rpm?

I wouldn't think that 200k was that old for a subaru. don't get me wrong, it's no spring chicken. mine has 188k and does just fine (not a subaru though)

I did an experiment once and started a thread. the title was "gunning it for FE" or something similar. I found that it is better to get up to speed faster and thus heating up your engine faster and getting into higher gear. mine is an auto trans so I don't have the luxury of changing the gears myself.

I would say to shift as low in the power band as you can. if you shift too early, you will get the sluggish reaction that you are describing.

If it takes 30 seconds to accelerate 5 mph then there is something seriously wrong with that car.

Does it use a lot of oil meaning the engine is on its last leg?

If it does not use a lot of oil a tune up, new air filter, and an oil change would probably help.

Is the check engine light on?

Have the codes read for free at Advance Auto Parts and correct anything the codes indicate is not working properly.

regards
gary

It is old. There are numerous problems with it, none the least of which are several engine sensors are dead. But yeah, that' what I had figured, but I wasn't 100% sure.

I can't say for sure about a car that's got lots of stuff wrong with it, but my 2008 VW gets great fuel economy when I floor it and shift early. I shift around 1200-1500RPM, entering the next gear at 1000-1200RPM (or occasionally right at idle) and keep up with traffic.

For most vehicles it is probably better to only step on it to 75% or so; when you go wide-open, most cars will go to an excessively rich air/fuel mixture and ignore the O2 sensors ("open loop"). That Subaru with several dead sensors is probably in open loop all the time anyway, so WOT (Wide Open Throttle) might work out ok.

Why doesn't your mom get some of the sensors fixed? Is she planning to junk it soon?

Basically, we are tight on cash, so any repair only impacts economy/performance is not going to happen.

I'm also pretty sure it's not the O2 sensor. I think it's the "knock" or "noc" or something sensor (never saw what it was written down, so I can only guess as to what the actual word is). The mechanic said it was some wierd thing that only was in older subarus. Anyways there is engine knocking at 1,200 RPM, so I'll just shift as low as possible while avoiding that.

Knock sensors are in every modern car.

You definitely want to avoid knocking.

Yup, because we sure as hell can't afford a new engine.

Take it to Autozone and they'll hook up a diagnostic scanner to the OBD-II port for free. That will tell you what the cel codes are, and you can sort out what to repair/replace from that information.

subarus get the subaru tick at 150k
(aka old ones are kind of junky)

had a friend with two of em who told me that