gwilson87 Posted September 3, 2009 Share Posted September 3, 2009 Ok so now that my brat's engine swap is done (enough to use as a daily driver at least) I can work on the boss' car. 1998 Impreza OBS, For a while the CEL has come and gone randomly. It has been checked and always comes back saying my cat is bad and knock sensor is bad. I have yet to do anything to fix either because the CEL would turn off for awhile before randomly turning back on. I am assuming the best course of action is to replace the knock sensor (I really don't want to spend $80 on something so small) and see if that fixes the CEL as well as my other problem. That other problem being the OBS is gutless on hills now. I used to be able to cruise up hills on the freeway doing 80 the whole way, now when I am in 5th and hit an incline I bog down REAL fast and have to downshift to prevent semi's from passing me Think maybe the new knock sensor will somehow help that? Or possibly are my cat's clogged and I just need to pull them off and hollow them out? (I don;t have to do emissions because of where this car is registered ) This is my wifes daily driver and our roud trip car and getting anywhere fun in utah requires driving up hills. Any info would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
lmdew Posted September 3, 2009 Share Posted September 3, 2009 The knock sensor will retard the timing, which will cause the performance to go down as well as the mpg. You can check the sensor resistance, the specification is in the repair manual. Take a good look down at the sensor, if its plastic shell is cracked, the sensor has seen better days. You could snag a used one out of the yard, but be ready to pull and check a bunch of them to find a good one. With the time you'll spend looking for a good one, buying new is not a bad option. I'd also check and clean the battery cables and all the ground wires. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted September 3, 2009 Share Posted September 3, 2009 knock sensor has caused those kinds of driveability problems before. i would start there and would give that a much higher probability of fixing the running issue, but of course there's no guarantee. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted September 3, 2009 Share Posted September 3, 2009 (edited) had same symptoms that you described on my 98 OBW, went to a auto parts store, where the counter guy pulled the codes. Indicated that the knock sensor was bad. Replaced the sensor, which fixed the problem. BTW, the codes can only be pulled when the check engine light (CEL) is on. Edited September 3, 2009 by Rooster2 added more info Quote Link to comment Share on other sites More sharing options...
gwilson87 Posted November 21, 2009 Author Share Posted November 21, 2009 Been awhile but finally got the knock sensor replaced. Car seems to be a bit more nippy around town (at least until the clutch, I think crapped on me... another story) But on the uphills in 5th it still bogs down. Went on a trip for work today and I was cruising the freeways fine, headed up a canyon and was accelerating and once i shifted to 5th it was like the car decided 60 was as fast as it would go regardless of how far my foot was in the floorboards. 4th gear gets me up just fine at 70 with the rpms at about 4500. This is with relatively new plugs also. Any thoughts about this? I long for how it was when I bought it, somehow doing 90 uphill... Quote Link to comment Share on other sites More sharing options...
lmdew Posted November 21, 2009 Share Posted November 21, 2009 I'd start with some good injector cleaner. If you pull your plugs, the color will tell you if one cyclinder is not operating as it should. Could be: - Plugs, Coil, Wires, Injectors, Fuel Pump, Air Cleaner.... If you just replaced the knock sensor, it may take the ECU a little while to fully reset. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted November 21, 2009 Share Posted November 21, 2009 I had a similar issue with my 96 Legacy. I'd be boogyin along at 70 on the interstate and hit a hill and have to downshift to keep it over 60. Was a big vacuum leak. The Evap purge solenoid had split a seal or something and air was just rushing right through when it was supposed to be closed. Fixed that and it's been peachy. Check around for split hoses. Any that are really hard (can't squeeze it with your finger) you should just replace. Quote Link to comment Share on other sites More sharing options...
gwilson87 Posted November 21, 2009 Author Share Posted November 21, 2009 I will jump on that monday. My wife doesn't like me to touch her car now, haha. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.