Hi everyone, new here but not new to subies. I currently have 2 '84 GL Wagons (one 2wd, one 4wd) and an '83 4WD GL wagon with such features as automatic transmission , a/c and adjustable lumbar support.

 

My question is this, my '83 has an issue with idiling while in gear. It idles rough and stumbles some up until about 2000rpm, after that it smoothes out... although it occasionally stumbles some (rarely). I was just wondering if anyone has any idea what this problem is (it does it in 2 and 4wd if it matters). My other 2 subies have had manual transmissions and an early 80's Subie with an auto seems to be a rare bird. Any ideas on what's going on?

 

Thanks!

The first things I would check are the regular tune up items. Plugs, cap, rotor, and most importantly, fuel fiter(or is it filters?).

 

Does your car have an ECU? if so, any error codes?

Welcome to the board. Indeed you do have a rare 83. Most 83/84 4wd's with AT were Turbo models. It sounds like you have a vacume leak somewhere. Listen for a whistle, but if you cant hear one, get a can of brake cleaner and spray (lightly) around the vacume lines. If theres a change in rpm's, you have a leak. The autos also have had issues with the vacume modulator. A line runs from the intake manifold to the passenger side of the trannie. Make sure this line isnt leaking also.

Rob

Rob, not all were turbo's. Remember my '84 beige wagon?

 

Back to the question, what are the rpm's while in gear and out of gear? When was the last tune up done? When was the last time the fuel filters have been replaced?

I had a thought that it may be the fuel filters; I haven't c hecked them yet, but will replace them asap. I will also check for the vacumn leak also... very plausable considering the hoses are what? 21 years old...

 

I really have no idea if the car has an ecu, but just guessing I would say no. I have no idea when the last tune up was done, since I've had the car it has had:

 

New starter, new water pump, new ignition switch, new neutral safety switch, plugs, maybe cap.... The rpm while in get ranges from 1000-500 and it barely keeps running at 1000. Out of gear it's like 1500 w/out choke and 2000 with the choke on. It's insane, but it seems to be what the car needs to keep running... deff not the best for gas milage eh? Anywho, I'd really love to get my subie back to normal, it really is a totally awesome car otherwise.

 

Thanks for the help gang, keep it coming!

ECU is mounted to the bottom of the steering column if you have one. Take the colored 6" x 15" piece of trim that is right above your shins off and if theres a box with an LED you have an ECU.

 

Another giveaway to having an ECU is an O2 sensor but I have seen people put a junkyard exhaust system on from a car with an 02 onto a car without need for one.

Ok, so I haven't checked for the ecu yet, I did manage to get both fuel filters taken care of today. The rear one had a little crud in it, and after a test run it seems to taken care of the upper rpm stumble, from 2k up in 3rd gear it ran great all the way up. (pegged the speedo, hehe) It still however has an erratic idle and the stumble below 2k. I did a quick check for a vacumn leak as advised and I didn't discover any, I still need to go thru it really well. I'm still kinda stupified on this whole idle thing though.

Can you hear the idle change or are you seeing it in the form of TACH jumping?

Originally posted by ShawnW

Can you hear the idle change or are you seeing it in the form of TACH jumping?

 

Both.

 

Since my last reply I've replaced about half of the vacumn lines, the plugs, wires and the vacumn modulator valve in the transmission. I still have the proble. It's driving me insane!

Originally posted by Turbone

get a can of brake cleaner and spray (lightly) around the vacume lines.

 

Not trying to be picky, but brake cleaner does very bad things to rubber and plastic, carb cleaner would be a better choice.

Oh yeah, I did the vacumn test, could hear nothing and also no increase in RPM. I'm thinking carb?