Unable to solve my misfire problem

[DanSVX94]

I've posted about this before. Above about 55 mph I get a random misfire. If I drive 5 miles at 55 and above it happens about 3 times.

Here's what's been done:
1) Brought to my Subaru dealer, they experienced the problem but were unable to solve it. They suggested I replace ignition switch -- which I did but problem persists.

2) Tom installed 3 new coils driver's side -- didn't work. So he moved them to passenger side -- no go. He also checked for bad grounds.

3) I brought the car to a local mechanic recommended by a friend with an Audi that has 220,000 miles. The guy couldn't find the problem (he didn't charge me), but he did experience it on a test drive. He suggested it might be the computer. A member on this forum sold me an ECU, but this didn't solve the problem either.

4) I ran a bottle of injector cleaner through gas tank.

Tom put in new plugs, timing belt, etc in January 2007.

The car drives great, with the exception of this one issue.

Any ideas? Could it be an injector issue? If so, how should I check it out?

[alia176]

Had a similar problem (but worse) in the wife's '95 legacy. It was a relay inside the vehicle that was failing intermittently. I swapped out various ignition parts during the troubleshooting phase and nothing helped. Sold the car before tearing into the relay issue. It may or may not be related to your issue.

Good luck.

[DanSVX94]

Which relay?

[alia176]

Crap, I knew you'd ask me that question and I don't have a good answer for you If memory serves, it had something to do with the Ignition system and is located on the driver side kick panel in a '95 Legacy. Search the legacy board for " cylinder misfire" or "P0303" and this should turn up.

Sorry, can't offer more details on this!

Cheers.

[Hocrest]

Someone else just posted about a problem they had where the plugs were loose in the ignitors. The ingnitors are in the center of the firewall directly above where the dogbone attaches.

Just a WAG, that takes about 30 seconds and $0 to check....

[svxpert]

<<I've posted about this before. Above about 55 mph I get a random misfire. If I drive 5 miles at 55 and above it happens about 3 times.>>

when did this start? after any services? did you change the fuel filter? how do you know its a misfire exactly? what symptoms does it have?

[TomsSVX]

Originally Posted by svxpert

<<I've posted about this before. Above about 55 mph I get a random misfire. If I drive 5 miles at 55 and above it happens about 3 times.>>

when did this start? after any services? did you change the fuel filter? how do you know its a misfire exactly? what symptoms does it have?

It is like the car stalls for a split second and then comes back. No lights show up on the dash... nothing, just business as usual.

Tom

[SomethingElse]

Have you checked fuel pressure yet? hook the gauge up and tape it to the windsheild so you can read it while driving.

Also does it feel like it could be in the transmission? Try putting it in 3rd and see if it still does it. maybe a lockup solenoid? hold the brake pedal slightly while your accelerating. if im not mistaken the trans wont engauge lockup with brake pedal pressed.

[Trevor]

Originally Posted by TomsSVX

It is like the car stalls for a split second and then comes back. No lights show up on the dash... nothing, just business as usual.

Tom

Tom what a bummer. In an effort to assist, about all one can do is jog your thought processes. One would expect a code to be recorded and held, if it were any item so covered. You must be near up the wall.

It some how smells electrical. Do you get the impression that all cylinders drop out, or only one? From what you say it is probably a loss of all six. Have you tried substituting another igniter? Solid state high current switching is involved, at this point in the circuitry and there could be something intermittent here. I don't think a code would be recorded.

There have been suggestions regarding an intermittent in the primary side of the HT circuit, i.e. ignition switch, relay or what have you. I would say the main relay could be what has been referred to in this regard.

Any suspect circuit can be checked by wiring a small relay across the circuit, held closed only via its own normally open contact. If the circuit fails for a split second the relay will drop out and stay out, thus providing a positive indication.

A specific speed has been mentioned when the fault occurs. Is this absolute and is it related to throttle position, engine load, RPM, or any other fixed factor?

This all no more than going over what you already surely are aware of and I hope does not annoy you as being useless clap trap.

Cheers, Trevor.

[TomsSVX]

Originally Posted by Trevor

Tom what a bummer. In an effort to assist, about all one can do is jog your thought processes. One would expect a code to be recorded and held, if it were any item so covered. You must be near up the wall.

It some how smells electrical. Do you get the impression that all cylinders drop out, or only one? From what you say it is probably a loss of all six. Have you tried substituting another igniter? Solid state high current switching is involved, at this point in the circuitry and there could be something intermittent here. I don't think a code would be recorded.

There have been suggestions regarding an intermittent in the primary side of the HT circuit, i.e. ignition switch, relay or what have you. I would say the main relay could be what has been referred to in this regard.

Any suspect circuit can be checked by wiring a small relay across the circuit, held closed only via its own normally open contact. If the circuit fails for a split second the relay will drop out and stay out, thus providing a positive indication.

A specific speed has been mentioned when the fault occurs. Is this absolute and is it related to throttle position, engine load, RPM, or any other fixed factor?

This all no more than going over what you already surely are aware of and I hope does not annoy you as being useless clap trap.

Cheers, Trevor.

Trevor, the speed really has nothing to do with it...

When you are driving, a slight miss can be felt when accelerating... but since the TC is not locked, it goes relatively unnoticed. When the TC locks is when he can really feel a miss and to be honest, since it revs at relatively low RPMS at 55 or so MPH a single cylinder miss can be quite noticeable... Not having access to the car is definately a tough wall to climb if I am to diagnose and I am at the same point as anyone else in trying to help from a distance... This issue still cooks in my mind everyday though as I try to figure something out for him

Tom

[Suby Fan]

hows the fuel pressure durring the misfire? (sorry if i missed someone saying its fine)

[svx_commuter]

Originally Posted by TomsSVX

It is like the car stalls for a split second and then comes back. No lights show up on the dash... nothing, just business as usual.

Tom

Might be worth a try to swap fuel injectors. They might be sticking and that would not show up a code.

How about the TCU shuting off the engine thinking it is shifting?

[DanSVX94]

I've contacted Subaru of America and they contacted the dealer where I brought the car for evaluation. The dealer just says they need more time to figure it out. They don't say how much time, or what they will do to figure it out. So I told SOA that it doesn't make sense for me to just write the dealer a blank check when I'm given such sketchy info. I asked SOA to tell me who their top problem solver is. They just say dealer dealer dealer. Very frustrating.

[Trevor]

Originally Posted by DanSVX94

I've contacted Subaru of America and they contacted the dealer where I brought the car for evaluation. The dealer just says they need more time to figure it out. They don't say how much time, or what they will do to figure it out. So I told SOA that it doesn't make sense for me to just write the dealer a blank check when I'm given such sketchy info. I asked SOA to tell me who their top problem solver is. They just say dealer dealer dealer. Very frustrating.

Unfortunately this is understandable in respect of an intermittent fault which is difficult to locate.

I notice that you have a theft Deterent System. If this is in the form of an engine immobilizer, there will be parallel connections which could result in a fault. I present this as rather a long shot, but if the unit can be easily disconnected, this could be worth a try. Particularly if there is any relationship regarding time of installation and the problem commencing.

[svxpert]

<<I asked SOA to tell me who their top problem solver is. They just say dealer dealer dealer. Very frustrating.>>

do you really expect SOA to help you fix your car? thats why dealers pay SOA for the service and name rights.