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low rpm misfire on 97 outback
Posted: Thu Sep 25, 2014 7:40 pm
by gazcull
a couple of weeks ago i bought a 97 outback very cheap that was running pretty rough, (misfiring badly) i checked the error codes and it had two, a 22 knock sensor and a 32 oxygen sensor, i started with the knock sensor which i replaced but eventually found a broken connection on one of the multi-connectors, repaired and cleared ecu codes and the car ran great
until it was warm , it has a low down misfire and seems short on power but is coming up with no error codes now (the o2 sensor fault has disappered) , it does run alot better than it did thou. is it worth replacing the o2 sensor? i have already replaced the plugs , leads, fuel filter , help much appreciated, thanks
Posted: Fri Sep 26, 2014 2:34 pm
by steptoe
injector abit dirty?
Posted: Fri Sep 26, 2014 6:21 pm
by TOONGA
The O2 sensor should in theory be replaced at 80 000 -100 000kms.
I replaced mine with a newer unit from a low KM wreck, and it did make a difference to engine power and economy.
Is this a twin cam motor or single cam motor? as the twin cams are prone to headgasket leaks.
TOONGA
Posted: Sat Sep 27, 2014 1:18 pm
by gazcull
its the twin cam engine, might be a head gasket leak, but not using any water or showing any other signs, any fool proof check i can do?? i think ill try a new sensor anyway and maybe some injector cleaner
Posted: Sat Sep 27, 2014 7:14 pm
by tambox
From the dates you give, does it have shim tappets or Hydraulic?
Pop a rocker cover off and check the valve clearace.
Posted: Sat Sep 27, 2014 7:16 pm
by steptoe
then there is the question of correct plug type and part number for the engine
Posted: Sun Sep 28, 2014 2:02 pm
by gazcull
the engine is EJ25DNXDJE and i put NGK BKR6E-11 plugs in , it had NGK PFR6B-11 in before
Posted: Sun Sep 28, 2014 7:07 pm
by tambox
If it is the original engine, it will be a shim adj tappets.
Non shim DOHC engines only came out 95/early 96 from what I have found out.
Costs nothing to check them and having just bought the car, it would be worthwhile.
Posted: Mon Sep 29, 2014 3:35 pm
by gazcull
i will definitely check that out, im pretty sure the car was fitted with reconditioned heads at 150000km and the head gasket done and the water pump looks pretty new to , its done 195000 now so nearly 50000 on new heads
Posted: Mon Sep 29, 2014 6:45 pm
by tambox
Bout time to do the tappets.
Posted: Tue Sep 30, 2014 9:37 pm
by gazcull
got stuck into checking the tappetts here's wot i found:
cylinder 1 inlet 0.18mm and 0.15mm
exhaust 0.23mm and 0.23mm
cylinder 2 inlet 0.14mm and 0.15mm
exhaust 0.21mm and 0.23mm
cylinder 3 inlet 0.20mm and 0.18mm
exhaust 0.26mm and 0.24mm
cylinder 4 inlet 0.18mm and 0.18mm
exhaust 0.23mm and 0.25mm
according to my haynes manual inlet should be 0.18 to 0.22 and exhaust 0.23 to 0.27 so most inlets gaps are too small and most exhausts are pretty close to , never done these shim tappets before, is it hard? are the shims available/expensive ? and the manual says i need special tool as well
Posted: Tue Sep 30, 2014 10:06 pm
by tambox
The OEM 97 legacy manual lists in .20-.22 ex .25-.27.
The clearances you have will not give you the problem you are trying to sort out. They will reduce the "efficiency" of the engine by "x" amount.
The shims are easy to do, with the motor out:D
They are fiddly to do in the car, I use a flatbalde screwdriver and magnetic pick up tool.
The pain is, you have to take them out, measure them, work out what size you need, then fit them. Not much fun if you need to drive the car to get the new ones = double remove/refit.
They are not cheap, try the wreckers or a Subaru motor rebuilder.
But once they are done, provided everything is running well, they won't need doing for while.
Find the problem before you do the shims.
Any white condensation/sludge under the rocker covers?