1997 subaru legacy gt 2.5 cylinder misfire

[jemrami9]

Greetings. Hope to get some help or guidance on this issue please. I have a 1997 legacy GT wagon 2.5 that started missing occasionally at start up. Was usually in the morning first thing and went away after a few miles. Just figured wires were shot so I replaced the wires and plugs. Well things got worse after that as far as the misfire went. Plugs were gapped etc (NGK) and CEL would flas during the misfire episodes that would last for a min or 2 at most then it would go away. CHecked codes and comes up with misfires on cyls 1, 3 and 4. Replaced coil next. Car worked great for 5 mins and misfire would occur again however no blinking CEL this time but misfire is there. What could the problem be? Not sure what else is in line as far as this problem goes. Any help would be totally appreciated. Additionally, if there are any Subaru Mechanic gurus near madison WI that could help me out, let me know. Thanks in advance!

[SuBrat84]

I'm going through this same problem on my 97 Outback right now. Did you use Genuine Subaru Wires? I'm told that can make a huge difference because of the "wasted spark" system these engines use. Did you get the NGK Platinum (PFR5B-11) plugs? They are a must have for these as well. It's hard to spend ~10-15 per plug.. but you gotta do it.

I'm also told the knock sensor can be a culprit.

Or fuel injectors. (Fuel Filter?)

Cam / Crank sensors

Timing Belt Slipped?

 

If you get it figured out PLEASE let me know! I'm waiting on Plugs (NGK PFR5B-11,) Wires (Genuine Subaru,) Fuel Filter, PCV Valve right now.. if any of that helps mine I will let you know.

If none of that helps I will be inspecting my timing belts.. because looking at them is the next chepeast (free, my labor) thing. If the belts are fine then it's time to start replacing sensors (even though I'm not getting sensor codes.) And then fuel injectors... Please don't be fuel injectors.. lol.

[jemrami9]

Very good. Yes let me know what shakes out. I did replace the knock sensor like 6 mos ago. Didnt get genuine subaru wires though. Might have to try that. I will have to check what NGK plugs I got. They were platinum ones but were only like 4 bucks apiece..... More to follow. Thanks again though, hope to get this sorted out....

[SuBrat84]

I have heard that the angle and torque of the knock sensor can effect our engines in this manner.. I haven't found the spec for it yet though. Did you do it yourself or a shop?

[dr.b]

your rings could be going, or just one ring with bad compression, the new plugs making it worse makes me think one. Find someone with a compression tester. but i hope its just plugs , good luck.

[jemrami9]

yeah I put the knock sensor in myself actually..... hmmmmmm

[jemrami9]

anymore feedback on this one?? Any subaru mechanic gurus near madison wi???

[SuBrat84]

Plugs, Wires, Fuel Filter, PCV Valve.. car ran great for about 35 miles.. problem came back.. car died. Car wouldn't start at all. Couldn't hear the fuel pump.. pulled it out.. put power to it.. it turns.. put it back.. car drove home 5 miles just fine.. Think it's a fuel delivery issue at this point.. Bad/clogged impeller in the pump.. something electrical? Maybe something to do with the fuel level sensors?

Does your gas gauge work? Mine is erratic but mostly doesn't.

[jemrami9]

yeah fuel gauge works. Actually found out the # 4 cyl was misfiring. Turned out the end of the plugwire was cracked. Part of the rubber boot is stuck on the plug now. A new delimma now lol go figure. How on earth can you remove the 1/2 inch of rubber boot from the plug??? UGH... in the meantime I used the old wire and connected the contact on the plug itself and slid what was left of the hard plastic shield over the plug and slid the red rubber cap over the top.... Misfire is gone however im sure that wire being rigged like that probably wont last too long. If anyone has any ideas on this one I would love to hear.

[SuBrat84]

All four of my plug wires did that. 3 of them I was able to get out with a 13mm deep socket and a 4" extension. It was not easy. The #2 one would not come out with the socket.. I was able to grab it with a needle nose pliers... Good luck.

 

Edit: A "Small" pair of needle nose pliers might be your best bet.. I didn't have a small pair and was just working with what I had.

[jemrami9]

13mm deepwell huh? I will give that a shot...... I have the joy of it being the # 4 cyl. Looks like a straight shot in there once I take the washer fluid reservoir out. I will give it a shot.... Thanks! More to follow....

[SuBrat84]

Looking from front of car:

----Firewall-----

Air 3|4 Washer Fluid

Box 1|2 Battery

----Radiator----

 

(Fixed, my bad.)

Edited July 9, 2010 by SuBrat84

[Olnick]

Actually, 1 and 3 are (front to rear) on the passenger side.

2 is drivers side (front) near the battery, 4 is drivers side (rear) near the washer fluid reservoir.

[SuBrat84]

Seriously? Weird.. memory dislexia i guess.

[jemrami9]

Crap, replaced coil plugs and wires. Still has the misfire occasionally. What next????? ugh...

[SuBrat84]

Here's my list of possibilities: (Since we've both done plugs and wires.)

Knock Sensor; Make sure the mounting surfaces are clean, make sure the sensor isn't touching any other parts of the engine except where the mounting surface is at. 15-17 Ft. Lbs. of Torque. (I did this last night and went for a ~40 mile drive without a problem. But, it wasn't 110 at night either.) A Bad Knock Sensor should throw a CEL. But, I guess it being installed wrong can cause these issues.

MAF Sensor; I guess they sell a MAF Cleaner. A dirty MAF may or may not contribute to this issue. A totally BAD MAF should throw a CEL.

Alternator; Maybe still functioning enough to keep the system charged and running but not producing enough current for a GOOD spark. (Try turning off as much electrical stuff as you can and see if it helps. Headlights, stereo, ac/vent fans, etc.)

Fuel Pump / Sending Units; May be clogged or dying, not providing enough fuel pressure / May not be providing good input to fuel levels?

Fuel Injectors; May be dying and not putting enough fuel into the combustion chamber for a good burn.

Coil Pack; Failing, not giving good spark.

 

Did you say you replaced the coil pack? Basically I'm going to go down the list one by one doing the cheapest stuff first until the problem goes away and doesn't come back. Since cleaning/adjusting is the cheapest thing I can do I am going to clean/adjust as much of that stuff as I can before I start buying more parts. I'm really keeping my fingers crossed that it was the knock sensor. (Mine was touching where the wire comes out of it so I think it was picking up a "ghost knock." It was also WAY too tight.. I could barely get it loose. I torqued it down to about 15 ft. lbs.)

[bstone]

Replace the ECU? It might be shorting out the coil pack.

[SuBrat84]

I was out today in the 110F sun driving across town and idling in the parking lots with the ac going with my son in the car and didn't have a single problem. I'm really really keeping my fingers crossed that my knock sensor was not installed properly and now that it is everything will be fine.

[bstone]

Rooting fer ya. If it comes back just know we'll be here.

[jemrami9]

Gonna check the knock sensor next, got a knock sensor code now too, go figure..... Sounds like you may be in luck there, sweet!!! I hope I can get the same result lol toss some karma this way...

[SHiggins]

Hi everyone,

 

I'm having some similar problems with my 92 legacy. I replaced the plugs, wire and distributro coil and now only the #1 and #2 coil connections are firing on the coil. The #3 and #4 are dead. Has anyone seen this before? any thoughts?

 

Thanks,

Scott

[bstone]

Replace the ECU. You might need a new coil.

[1-3-2-4]

So whatever was the outcome for this?

 

I have a 97 outback and I have a knock sensor code and I have a misfire on cylinder 3 & 4 My knock sensor should be here Tuesday or Wednesday.

[RustyBucket]

Hi All.   Just another data point for y'all.   1997 Subaru Legacy Outback 2.5 DOHC, Auto, 220K miles, original owner.   Top end professionally rebuilt 7 years ago at 134k due to blown head gasket.  Car has generally been very good with no other significant problems.  About a 2 years ago and 20k miles ago, developed erratic miss, mostly at idle but also irregularly apparent at speed under low load.   Swapped in new plugs and wires (no 2 or 4 [i forget] was singed at contact to plug).  Problem solved.

 

About a month ago again developed erratic idle miss.  Doesn't happen when stone cold or until somewhat warmed up, more noticeable when fully warm and (for instance) sitting at a light.  It is an sort of 'stutter cough'.  2 or 3 misses, then idle smooth for a few seconds, then a another little cough. Disappears as soon as RPM picks up, no hint of it at speed or under load.    Checked plugs, they look good, and swapped in another fresh set of wires (thinking that #4 looked like it had what might be a burn mark from arcing across the face of the rubber boot between plug and plug well of cylinder).   If had cured problem would have been $30 well spent.

 

Problem persists.   No idiot lights, no other apparent problem. Oil has been consistently changed every 4 to 7k miles for life of car.  Burns/drips (gasket leaks) about a quart every 1500 miles now.  Cali car, nearly always garaged.   Need to get 3 more years out of her, that means at least 2 more Cali smog checks - so it'll need to be fixed by April at the latest.

 

I could start throwing parts at it, or I can hand it to my mechanic with a blank check (they are good, but not cheap), but I'd rather just find and fix the problem - I've a sneaking suspicion it will be something insanely simple - but the car isn't really telling me what it wants. 

 

Any similar symptoms and what was your fix?  Thanks.

[later_Peter]

I had trouble after I replaced wires & plugs. I was going to replace the wires because they were unknown brand... when I went to remove them I found that 2 of the wires were not seated properly... (seems like an issue with the design of "generic" wires...)... I reset the wires & all was well...