Subaru Forester goes Open Loop far too easy

[primemover]

I've got a 98 Subaru Forester, and I'be only been getting around 20 mpg in just about any type of driving. Now granted, it is winter, and it is lifted 2" and riding on 30" all terrains, but I think I should be able to do better. To that end, I've been looking into a few things. Using Torque I noticed that the car seems to open loop way early, like around 20-25%, no matter what the rpms/load. Anyone have any ideas? My understanding is that most cars shouldn't go open loop until much higher load.

[nbleak21]

In winter my Acura goes into open loop even at partial cruise throttle. (cat/O2 sensor gets too cold, due to my FMU)

What are your coolant temps at when this happens?

[primemover]

Don't know the exact number, but basically normal operating temperature, smack dab in the middle of the temp gauge. Same as in summer time. Torque even announces to me that I've reached operating temp.

What's an FMU?

[nbleak21]

"operating temp" can mean thermostat open, or 02 catalyst temp is hot enough for closed loop, both of which can decrease dramatically in the winter causing the vehicle to go back into open loop, especially those of us running leaner then stoich! (EOC, DFCO, Lean burn, etc)

FMU is an analogy for Fuel Management Unit. I run a VAFC (piggyback microprocessor that wires into the ECU and engine sensors) in my acura to lean the engine out during light load cruising, and to dump a little extra when I get on it to compliment I/H/E. (pic of VAFC attached)

unsure how familiar you are with torque, but you can build custom monitoring pages that really help out with F/E. (screen shot attached)

[redpoint5]

My Acura almost never goes open loop, even when I just start the engine and it's cold out. It really only goes open at full throttle or DFCO.

Originally Posted by nbleak21

unsure how familiar you are with torque, but you can build custom monitoring pages that really help out with F/E. (screen shot attached)

You get 36.5 mpg in your CL!

Is there some computer trickery for my TSX, and do you recommend it?

[primemover]

I haven't had a chance to keep track of the open/closed loop status when its warmer but the mpg isn't that much better in the summer. I don't think temp is the cause here.

FMU sounds very handy.

Very familiar with Torque, it's great!

[mwebb]

Originally Posted by primemover

Anyone have any ideas? My understanding is that most cars shouldn't go open loop until much higher load.

TPS relative to rpm , look at knock retard as well, it may be going to open loop because
the system detects excessive ping followed by knock retard

not the air / fuel map.

swap OEM size wheels and tires back on and re test
or
try a tank of High test to see if knock retard is lessened OR you can get a higher load value prior to changing to open loop
BEFORE chasing ghosts

ultimately
increased drag coupled with change in final drive ratio
changes everything

[primemover]

I'll try having a look at the spark advance. There's also a knock detector plugin for torque I'll give a try.

One big problem I've had with torture and this var is the slow pid read rate. I only get about 2/sec. I get 6/sec in my wife's 99 Mazda 626. Anyone here with a Subaru of the same era have any feedback on the kind of pid read rates they get?

Unfortunately swapping back to stock size wheel assemblies is non-trivial. I'm reassured by the fact that the mpg was not that much better with the stocks.

[arcosine]

My Saturn is closed loop all the time , except when warming up, then it's too lean.. I have the mod posted here somewhere. If your timing is retarding, use premium gas..

[Xist]

I have a 1999 Forester, but live in Arizona. Down in the Phoenix area, it is always in closed loop--I am not sure that I have ever accelerated hard enough to open the loop. My parents live in the mountains and when I accelerated hard, it would go open loop, but the temperatures were probably twenty degrees or less, not something that I will ever see in the Valley!