My Green Monster has developed hesitation or 'bucking' on average acceleration and while I'm idling it presents mild popping noises from the exhaust, I assume. Also, is there a periodic maintenance schedule for the engine noting points in time when the car needs to see someone more knowledgeable than I.?
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If it developed suddenly I'd check for a loose or worn plug wire, or possibly a loose connection to a sensor or the ECU. You might have a bad plug(s). You might have a bad sensor (crank, intake air temp, coolant temp, MAP). You might have gotten some bad gas, have a clogged filter, or clogged injector. If you have a factory ECU you should have a OBDII port to do diagnostics from with a code reader.
Regular Maintenance for these is oil & filter, plugs, air filter, fuel filter, and valve clearance. Cam belt, too, but only every 100,000 miles or 5 years. Download a Subaru Forester manual online and follow that schedule for a guide.
The absolute first thing to check is battery voltage, especially engine running. If the alternator has failed, the injection/ignition will probably not be working properly. The computers don't like it when the voltage is low.
Good call, @DannyP! That is the first place to go on a car that's stored a lot of the time.
Vacuum leaks can do weird things like that too.
when I had my subie speedy, I had similar personality change, and it turned out to be a plug from the block blew out.
A very astute mechanic solved the mystery for 5 dollars, thought I had an exhaust leak or blew the muffler.
good luck.
Hi , I believe you had you car converted to Suby power recently by Special edition as I have. Correct? If so you have in essence a new engine. As others have suggested the first thing I would do is hook up a scan gauge to the OBDII port. I would contact Carey he knows more about the suby engine than most anyone. I am sure it is something simple. If you have low voltage the scan will alert you. I bought a scan gauge that stays plugged into the port and is read via an app. on my phone, so I can monitor the engine stats anytime I want. It will also send an alert to my email if a code is thrown. Something you might want to look into getting if you haven't already. Good luck finding the issue and let us know what it turns out to be, it will help us Suby guys in the future.
Certainly needs basic maintenance.
I would get a small code reader and see what it gives you in the meanwhile, clean the K&N filter and the MAF sensor and this could cure your issue.
A dirty air filter and MAF can drive you crazy with the bucking bronco routine. 
Regarding code readers... it's amazing what you can get these days that connects wirelessly to an app on your phone!
I bought one for each of my kids and my wife, so there is one in every ride.
The Android version works on either Bluetooth or Wifi, but the Apple stuff REALLY needs the Wifi version. Just something to be aware of.....
I have one with blue tooth and it works well for us. We have used it on Audi TT, Subaru EJ, and VW jetta.
We use Carista pgm on the iphone and it reads and clears codes.
N.B. You do not have to sync up with bluetooth at all, a step that sometimes confuses users, it just automatically finds it. and reads the codes when you open the program.
...loose spark plug connector...didn't see it first time around...
I love an easy fix!
Why does that sound familiar to me?
You're southern neighbors, maybe?
Nah. I think I may have heard that from you a couple of times.
Glad you found the issue. 9 times out of 10 it is a simple cause.
I was tuning the dual carbs on an engine and it was running rough. So I used a laser heat sensor on each header pipe as it left the cylinder to find one was 120 Deg. F and the other three in the 570 Deg.F range. Oh I have a dead cylinder I thought and all kinds of doom and gloom went through my mind. I then realized I left one of the plug wires off while cleaning the engine. Boy was I relieved and embarrassed.
Welcome to the club...
Thread drift warning!
Once, before one of my first treks to the mountains in the Speedster, I gave the engine a good cleaning, along with the rest of the car, the day before the trip. The next morning I left during rush hour. Shortly after I merged onto one of our huge, high bridges over one of the ship channels, right after getting into the left lane (cuz I was feeling speedy), the engine cut out. No sputtering, it just died. In the left lane. Going up hill. At rush hour. On a bridge full of 18-wheelers.
Somehow I was able to coast it across three lanes of unhappy traffic and get into the truck climbing lane and pull as close to the railing as I could. Traffic immediately backed up, and since I was partially blocking the truck lane, the truckers were NOT happy. I put the flashers on and walked away from the car, believing that it getting hit was inevitable. I called Hagerty for a tow and was told it would be a while. Meanwhile, one of the Department of Safety trucks pulled in a little behind me and put on all of his flashing lights to warn traffic to move over.
With him behind me I felt safe enough to open the engine cover and take a look, only to find one of the coil wires ('+', I believe) floating in the air. I plugged it back on, got in, and the car cranked right up. Obviously I had knocked it loose, but not fully off, when I cleaned the engine, and it vibrated the rest of the way off at the worst possible time.
The moral of this story is that the simple stuff happens to everyone.
We now return to our regularly scheduled thread already in progress.
Engines with dual single throat knock off 34's Webers or Kadrons will drive people nuts trying to figure out why the engine is running in two cylinders ( 1 & 3) at opposite sides of the engine at idle, what happens is two of the four cylinders rob the fuel for the other two cylinders ( 2 & 4) at idle. You would swear it was wires or plugs....Installing a balance tube between the intake manifolds resolves the problem.
@Lane Anderson posted:Thread drift warning!
Once, before one of my first treks to the mountains in the Speedster, I gave the engine a good cleaning, along with the rest of the car, the day before the trip. The next morning I left during rush hour. Shortly after I merged onto one of our huge, high bridges over one of the ship channels, right after getting into the left lane (cuz I was feeling speedy), the engine cut out. No sputtering, it just died. In the left lane. Going up hill. At rush hour. On a bridge full of 18-wheelers.
Somehow I was able to coast it across three lanes of unhappy traffic and get into the truck climbing lane and pull as close to the railing as I could. Traffic immediately backed up, and since I was partially blocking the truck lane, the truckers were NOT happy. I put the flashers on and walked away from the car, believing that it getting hit was inevitable. I called Hagerty for a tow and was told it would be a while. Meanwhile, one of the Department of Safety trucks pulled in a little behind me and put on all of his flashing lights to warn traffic to move over.
With him behind me I felt safe enough to open the engine cover and take a look, only to find one of the coil wires ('+', I believe) floating in the air. I plugged it back on, got in, and the car cranked right up. Obviously I had knocked it loose, but not fully off, when I cleaned the engine, and it vibrated the rest of the way off at the worst possible time.
The moral of this story is that the simple stuff happens to everyone.
We now return to our regularly scheduled thread already in progress.
Same thing happened to me as well. I was in a remote part of our mountains on a twisty back road with no cell service and no real tools. The car quit on me and just stopped running. I opened the engine lid bent over the opening and took a visual survey. Not seeing anything immediate I started touching all the wires that give spark. The first thing I touched was the coil wire and sure enough the metal contact had come out but the tip of the rubber boot was still attached. Pushed it back in and off I went. No doomsday Deliverance scene for me.
loose coil wire stranded me too, put a little crimp on it and good to go
May you never have a fresh built long block, assemble & bolt it in and the starter will crank no matter what I did it will not run .
Pulled it out of the speedster, hauled it 2 hours back to the guy that built it, he set it in the engine stand and fire right off and idles....we both look at each other and in unison say .....GROUND STRAP. ( and we had a beer) That scenario will only happen to me once ~
Whenever I have a sudden 'engine out' alert, I check the damn coil wires...and 10 times out of 9 it's the coil..
Meade
Are you Mead-ium or higher in certainty.
yes...
