Rough idle and lousy mileage, need some ideas, with ECU data

[suba]

The car: 90 L N/A 5mt AWD 200k roof racks

Recent work: Plugs, wires (OEM), ECT sensor (OEM), Walker brand O2 sensor, fuel filter (OEM), subaru trans and diff oil

The Problem: Recently my car has been running a little rougher (mostly at idle). it still idles at the correct rpm but will occasionly seem to almost misfire (most noticeable when started at operating temp, after sitting for a few minutes). Along with this little annoyance my fuel mileage has dropped to an abysmal 22 mpg. I hooked up the B10 scan tool and recorded the following data:

Cruise (level ground, 55mph, 85 deg F outside air temp)

System Voltage: 14.0 V
Speed: 55mph
Engine Speed: 2225 RPM
Coolant Temp: 178
Ignition Timing: 37 BTDC
Airflow Signal: 2.7 V
Load: 130
TPS Signal: 4.04
Inj Pulse Width: 6.144 ms
IAC Duty: 52.5
O2 voltage: 0 to .71 V
Fuel Trim: -3 to 0
Timing adj: 0
Baro Press: 698 torr

And at Idle after getting back to the house:

System Voltage: 13.92 V
Speed: 0 mph
Engine Speed: 700 RPM
Coolant Temp: 194
Ignition Timing: 20 BTDC
Airflow Signal: .76 V
Load: 36
TPS Signal: 4.68
Inj Pulse Width: 2.048 ms
IAC Duty: 37
O2 voltage: 0 to .79 V
Fuel Trim: -.78 to .78
Timing adj: 0
Baro Press: 698 torr

I intended to also get data while climing and descending a grade, but the inverter i was using to power the old laptop decided to crap out on me so thats all I was able to get.

Anyone have any ideas on where to look? I've hunted around looking for air leaks (starter fluid spraying on potential leak areas) but so far haven't found anything. And if you've made it this far into the post, thanks for the effort

[log1call]

Those figures look about right but static figures aren't so useful, you need to log the data to a spreadsheet with time, throttle position, temp, ipw, o2, Knock adjustment, revs and load. Then you can detect rich running, detonation, misfiring sometimes.
There is another free program to record data, it's called select monitor and can be got from... http://www.vwrx.com/index.php?pg=selectmonitor
It will work with a serial/ttl adaptor or a usb ftdi chipped seria/ttl adaptor cable worth a few dollars. The ftdi is the better alternative these days. Have a read here... http://www.vwrx.com/index.php?pg=selectmonitor. I have been using one of these ftdi TTL-232R leads directly to the diagnostic socket and it works fine. .. http://www.ftdichip.com/Products/Evalua ... 32R-WE.htm

Data is ok to look at but, the way the data behaves under different circumstances is the real diagnostic tool. As with all diagnosing you need to look at your initial data/symptoms, decide on likely problems/components, devise a test to load that component or induce the symptom, factor in the results of your first test and devise another test etc, Round in circles till you find what does cause the symptom, possibly several circumstances, then what one thing always causes the symptom if possible. Then if possible, wht one and only thing can always cause the problem. You need to be quite sure you know what induces the problem/symptom, not only as an aid to finding the problem, but also so you can test for it and be sure it is cured afterwards.

[wtdash]

You did the recent work before or after the idle issue started?
1>Double-check anything you touched - both ends of the plug wires/plug gap/etc.
2>Clean the MAF (w/MAF cleaner only.)
3>SeaFoam thru the intake (search on here)- - READ UP on this, as you don't want to hydro-lock your engine. I also suggest changing the oil soon after a Seafoam treatment.
4> Clean IAC (search on here)- Suggest using something other than carb cleaner, which may leave a residue.
Good luck,
TD

[PhyrraM]

On your warm starts do you notice any smoke?

Warm start problems, combined with idle misses and fuel milage problems lead me to think about a stuck/sticky injector. Temp sensor also...double check that it's the correct one and properly installed.

[suba]

Problems began before I did the work, figured a tuneup would rule out simple basic problems. The temp sensor is a subaru OEM sensor and no smoke on starts. I did seafoam the engine, but did not notice a difference.

As far as the IAC goes, what range should it be in? My understanding is that "normal" is about 45% (at idle) with less indicating a possible intake leak, but I'm not sure what +/- range that is in.

One thing I have been wondering about is the ignition system. Do the coils on this generation ever have problems that could result in weak output? I ask because the car acts at idle like the plugs are gapped wrong or something to that effect, but I double checked them when I installed them.