Subaru Legacy Wagon Hesitation problem
Hello, I have a 1998 subaru legacy gt wagon 2.5 auto. When taking off from a stop it has a hesitation like the engine tries to almost die out then the rpms comes up and it's fine. It does not do this all the time just here and there. Sometimes the check engine light comes on and when it does it and reads knock sensor. What do i have to replace to get it to stop doing this?
It sounds like either ignition or fuel delivery problems. If it is fuel, a good start point is to add a bottle of top engine cleaner to clear injectors etc. and possibly shift to a high octane, detergent added fuel such as Shell Optimax or BP Ultimate (there will be something similar in the US).
If that does not clear it, try looking at plugs (look up what clean plugs look like on the net) and possibly replacing plug leads.
After this stage, you are in to spedning some money with a good service agent. Ultimately, this may be the most economical route to investigating the problem.
Next thing to try would be the ignition coil, about $80 on-line.
My '98 Forester is running much better after those changes. A chipmunk had chewed my wires (!), but it's running smoother than even before that happened.
I did the things paisan suggest in order, though. First a tune-up (plugs), then plug wires. Then ignition coil.
That last one did the trick. Turns out a chipmunk had chewed up my wires and the coil failed. :sick:
No spark at all in #s one or two... the coil pack is operating properly? If so, then I can only think that it perhaps it is related to the timing, which is controlled by a trio of sensors: knock, crankshaft, and camshaft. At least, I think it was controlled by the sensors in '93, but I am not certain. If it is, the knock sensor retards timing in the event of detonation, while the crankshaft and camshaft sensors determine when to fire the plugs. They are mechanically based, with the crank sensor reading TDC position on the crankshaft sprocket and the camshaft sensor operating off a set of magnets embedded in the upper crankshaft sprocket on the driver side of the vehicle. Perhaps there was damage to one of those sprockets or one of the sensors. I would guess the camshaft sensor and/or sprocket is the most likely culprit if that scenario is true.
Hard to say though - all kinds of bad things can happen when a timing belt breaks. :sick:
i got the exact same problem on my legacy brighton 2.2 1999. Also tried the sea foam cans and fuel injector cleaner. Both oxygen sensors, plugs and wires have one year, new fuel filter and I've just changed the mass air flow and knock sensor, but still nothing does the trick... and still no check engine...
Have you solved your problem finaly? Did anybody?
Somebody knows anything new? Thinking about changing the ignition coil after reading this thread but, did it help anyone?
Anyone else notice a persistent hesitation? I have had a hesitation since new, I had it back at the dealer and each time they tried to tell me it would be fixed on the major service, they had no issues with it being reported. They changed the coils to no avail. I took the service manager out for a ride and we didn't have to leave the starting spot to notice it. He said that it was nothing. So I asked to go for a ride in his car. He said that wasn't fair because he didn't own a Subaru. I said why, because they have a hesitation problem. I had an Inpreza loaner and that car didn't have any such problem.
So I was an idiot and waited and now even the lemon law here in CT won't help me.
The hesitation is right as you attempt to accelerate from a stop. I can't depend on the car to get the 'jump' at a light so I have to sit and wait. I know if I was a teenager this would kill me!
I'd be interested to hear everyone's comments on this subject.
Needless to say, I bought my 2005 Outback 3.0R from a different dealer.
Did you replace the knock sensor yourself or did the dealer do it?