destey Posted March 5, 2007 Share Posted March 5, 2007 I did a search for my problem, but got such a wide range of answers I figured I post. Got a '95 legacy sedan, 5mt. During acceleration, I get power loss. It clears up if I pump the gas > 5x OR if the RPMs go over 3500. It also clears up (sometimes) if I push in the clutch. This problem happens most reliably when going slightly downhill. Changing the plug wires hasn't helped. Link to comment Share on other sites More sharing options...
nipper Posted March 5, 2007 Share Posted March 5, 2007 miles and engine please? Do you know if its an OBDI or OBDII car (do you have a spedo cable). Inspect your knock sensor. nipper Link to comment Share on other sites More sharing options...
Manarius Posted March 5, 2007 Share Posted March 5, 2007 Shot in the dark says Mass Airflow Sensor (MAF). My car did similar things when it was going. Link to comment Share on other sites More sharing options...
destey Posted March 5, 2007 Author Share Posted March 5, 2007 miles and engine please?Do you know if its an OBDI or OBDII car (do you have a spedo cable). Inspect your knock sensor. nipper Thank you for your replies. 2.2 obdII, but some version that's not entirely odbII compatable (not fully iso9141). I can't read it with my multiplex engineering reader. In 1995 the automatics work with all obdII, but the 5mt's don't work with my reader (others ??). Knock sensor I replaced a few years ago. I'll try swapping back in the old one and see if it helps. This problem happened a few years ago, but then went away, and now its back. I checked the tps sensor. It read voltages from 5 to near 0, going at a linear rate down by opening the throttle body. I might try a bit of seafoam in the pcv port. Link to comment Share on other sites More sharing options...
nipper Posted March 6, 2007 Share Posted March 6, 2007 Look at the throttle plate, see if its dirty. nipper Link to comment Share on other sites More sharing options...
destey Posted March 20, 2007 Author Share Posted March 20, 2007 Look at the throttle plate, see if its dirty.nipper Throttle plate looks clean. I changed the fuel filter, and swapped coils with another car, and still the same problem. Also something interesting: the problem happens under no load, but to a lesser degree. If I press on the throttle and hold it steady, the rpms will slowy decrease, maybe as much as 500 rpms. Then, like someone flipped a light switch, the problem goes away. 3-4 seconds later, the cycle starts again. I pulled the vacuum hose of the fuel regulator, and it did the same thing. Any ideas? Thx in advance.. Link to comment Share on other sites More sharing options...
Suzam Posted March 20, 2007 Share Posted March 20, 2007 Have you reset the ECU? Link to comment Share on other sites More sharing options...
nipper Posted March 20, 2007 Share Posted March 20, 2007 When was the last time this thing got a real tuneup? nipper Link to comment Share on other sites More sharing options...
lmdew Posted March 22, 2007 Share Posted March 22, 2007 I'd pull the plugs and see if you can see one cyc. that is not so good, buy the plug color. You might also do a compression check, but if the problem goes away it most likely not the problem. Link to comment Share on other sites More sharing options...
destey Posted May 23, 2007 Author Share Posted May 23, 2007 It was the upstream oxygen sensor. I had it up on the lift and noticed black soot around the cap to the sensor where the wires enter it. I wiggled them a little and they made a crackling sound. So I swapped the front and rear o2's (not hooking up the downstream one of course) and the thing runs better than it ever has. Somehow no o2 codes were ever thrown (poorly written data validation functions) Link to comment Share on other sites More sharing options...
unibrook Posted June 4, 2007 Share Posted June 4, 2007 Yep, I agree. Go for the front 02 sensor: My fix turned out to be the front 02 sensor. Here is my review from a diff thread: I have a 2001 Forester L with 85k miles on it. I have been chasing an intermittent hesitation under load problem for the past year. Only occurred when engine was warm. The front 02 sensor had been replaced once at 40k miles. I suspected it again this time, but since the only codes thrown had been cyl's 2&4 misfire ( p0302 & p0304) I assumed it must be ignition related. So I replaced plugs and wires 8 months ago...no effect. Did the dollar bill test over exhaust pipe, it was fine. Misted the coil, no sparks. I mentally sort of ruled out the fuel filter since it only happened when the engine was warm. Finally, a week ago while cruising on hwy at 65 mph, I felt the hesitation again (I wasn't even accelerating this time) and a new code was thrown....p0172. AutoZone read it for me, I described the symptoms to the guy and asked if he thought it might be the front 02 sensor. He said, "absolutely." So I decided to replace it next. Cost me $100.75 incl tax for the oem part# 22791aa00a from Cityside Subaru. I asked the Parts guy there if his experience was that this model engine needed a new front 02 sensor every 40k miles. He said, "no, these sensors are good for 100k miles." Well, bullsnot on that. I replaced the new front 02 sensor in 1 hour reaching from the top over the passenger side of the engine using an adjustable wrench. Be sure to use the thread lube so you can get it out easily next time.....after another 40k miles. I took out the air channel assembly first for better access. That seems to be the fix. No further hesitation since. Car runs like new. Link to comment Share on other sites More sharing options...
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