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96 Subaru Impreza Lost Power on highway + check engine light


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14 replies to this topic

#1 cascadeclimbn

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Posted 04 April 2014 - 12:40 AM

So I posted a week or so ago about a 96 subaru impreza outback I recently bought having hard shifting when warming up and check engine codes and also having lack of power going up a steep hill. Tuesday I was moving some stuff so I had the car loaded and was going up a long moderately steep hill when the car started losing power...it would rev up the rpm's but wouldn't go any faster and I had to pull it over. I pulled over shut it off and opened the hood. There was some slight smoking but very thin and a slight burning smell. I checked trans and oil levels and they looked good, and no unusual smell to either. I let the car sit for a while and started it back up. The AT oil light flashed 16 times then went away. I put the car in 3rd and drove slowly up the rest of the hill and then it ran fine the 35 more miles home. This event occurred in fwd mode b/c I throw the fuse in to increase mpg. I took it out and the last two days I've noticed the shifting is much smoother in awd (any ideas on that?) Anyways, This evening I was driving on a flat freeway and the same thing happened. I wasn't under load wasn't going up a hill but the car just wouldn't go even though the rpm's would go up. The check engine light started flashing while driving this time and I popped it into 3rd which allowed the car to actually go and I pulled to the shoulder and shut the car off asap. Turned it back on a few minutes later and the AT oil light flashed 16 times again. Drove it 3 miles to home where it's now parked. The codes are a knock sensor code, MAP sensor, and misfire in cylinder 2. Should I be continuing to drive this? Also can anyone help me figure out where to start with trying to fix this or tell me what could be going on? I don't have a lot of money so I can't afford to just do trial and error spoob but if I have to I guess I can not drive and save up.

#2 lmdew

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Posted 04 April 2014 - 04:39 AM

Two different problems.  The Flashing AT Temp light tells you there is a fault in the trans.  Search Torque bind.

 

The Knock Sensor fault will retard the timing which will degrade performance - power.

 

Misfire on #2, start with the basics, New NGK Plugs, New Plug Wires, Subaru or NGK and Sea Foam in the gas tank.

 

Map Sensor, Clean the connector first.

 

Misfires are not  a good thing for an engine and should be corrected to prevent additional wear and tear.



#3 grossgary

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Posted 04 April 2014 - 05:09 AM

The AT flashing is telling you the transmission computer is storing a fault  Personally I'd repair the engine issues first as they may affect the trans, though technically those shouldn't cause it to "rev in neutral".  But they're cheap and easy at least.  But the transmission issues are by far the most troubling in terms of possible expense and issues so I'd dig into those quick:

 

1. look up the procedure for getting that transmissino light to flash the code.  there's a complicated procedure (put key in, turn, open door, shift to drive, shift to park, shift to drive...etc, etc) and when you do that the AT light will blink the code for the issue (3 slow blinks is a 30 and 2 slow blinks is a 2 - so it would be a code 32).  you can find it online by searching.

 

2.  fluid is positively good?  never hurts to check again to be sure.  sounds like it is if 3rd gear works.

 

3.  is the transmission pan dented?
 

4.  do not use the FWD fuse if it drives better without it.  for future reference it doesn't help mileage due to the 4WD bearings, suspension, rear axles, rear differential, rear driveshaft, rear clutches, rear extension housing...there's a lot of weight and rotational mass still present.  'FWD' is not some magical elixir - it's a lighter system with fewer components and less weight - but that's not true with a 4WD converted to run in FWD or RWD.

 

 

 

Engine Codes:

clear engine codes and see which one comes back first.

 

Knock sensor - simply needs replaced. They're like $13 on ebay.

 

Misfire - classic spark plugs and wires - how old and what condition are they?

Spark plugs need to be original OEM NGK variety on that engine - start with those, they're cheap.

Spark plug wires need to also be SUbaru OEM or at least high quality.  Cheap wires can give misfires on that engine.

 

MAP sensor replace with a used one, they rarely fail and new is a pretty idiotic price for something so easy to replace.

 

cheapest way to get parts:

post in the parts wanted forum here
in the US (though Canadian yards are sometimes on here too):
www.car-part.com

ebay - used parts


Edited by grossgary, 04 April 2014 - 05:14 AM.


#4 cascadeclimbn

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Posted 04 April 2014 - 11:35 AM

The AT flashing is telling you the transmission computer is storing a fault  Personally I'd repair the engine issues first as they may affect the trans, though technically those shouldn't cause it to "rev in neutral".  But they're cheap and easy at least.  But the transmission issues are by far the most troubling in terms of possible expense and issues so I'd dig into those quick:
 
1. look up the procedure for getting that transmissino light to flash the code.  there's a complicated procedure (put key in, turn, open door, shift to drive, shift to park, shift to drive...etc, etc) and when you do that the AT light will blink the code for the issue (3 slow blinks is a 30 and 2 slow blinks is a 2 - so it would be a code 32).  you can find it online by searching.
 
2.  fluid is positively good?  never hurts to check again to be sure.  sounds like it is if 3rd gear works.
 
3.  is the transmission pan dented?
 
4.  do not use the FWD fuse if it drives better without it.  for future reference it doesn't help mileage due to the 4WD bearings, suspension, rear axles, rear differential, rear driveshaft, rear clutches, rear extension housing...there's a lot of weight and rotational mass still present.  'FWD' is not some magical elixir - it's a lighter system with fewer components and less weight - but that's not true with a 4WD converted to run in FWD or RWD.
 
 
 
Engine Codes:
clear engine codes and see which one comes back first.
 
Knock sensor - simply needs replaced. They're like $13 on ebay.
 
Misfire - classic spark plugs and wires - how old and what condition are they?
Spark plugs need to be original OEM NGK variety on that engine - start with those, they're cheap.
Spark plug wires need to also be SUbaru OEM or at least high quality.  Cheap wires can give misfires on that engine.
 
MAP sensor replace with a used one, they rarely fail and new is a pretty idiotic price for something so easy to replace.
 
cheapest way to get parts:
post in the parts wanted forum here
in the US (though Canadian yards are sometimes on here too):
www.car-part.com
ebay - used parts


Thanks for the good advice. I'll start with the plugs and wires today, reset the codes and go from there.

#5 grossgary

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Posted 04 April 2014 - 11:49 AM

knock sensor is also one 12mm bolt and easy to replace.  takes 10 minutes.  maybe 30 for a first timer reaching down in there.  having one of those extendable magnets is nice to have on hand but by no means a requirement or huge set back.



#6 cascadeclimbn

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Posted 04 April 2014 - 02:00 PM

Anyone know how to manually pull up the code on the AT light? I tried searching but couldn't find anything. Went down to the suburb dealer in town and they wouldn't give me the time of day because it was "lunch hour". Also earlier I stated the AT light flashed 16x when I started the car back up. Now it doesn't anymore...will I still be able to pick up the last code?

#7 cascadeclimbn

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Posted 04 April 2014 - 02:24 PM

http://forums.nasioc...ead.php?t=83901

I went here^ and followed those directions (3x) for the TCU "secret handshake" and my AT light stayed solid. I don't think it's a circuit issue b/c it works when something happens with the car. Is this actually the right method for a 96 impreza outback?

#8 MilesFox

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Posted 04 April 2014 - 02:29 PM

Runnint the duty c solenoid 100% (with the fwd fuse) can cause it to burn out, ans it does not normally operate at 100% duty. All of the running gear to the rear end is still the same amount of drag wheter or not there is power there, so there is no efficiency to gain by inserting the FWD fuse, but you may comprmise the duty C solenoid by doing so.



#9 cascadeclimbn

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Posted 04 April 2014 - 07:01 PM

So I took the car to the dealer today to pull up the transmission code and nothing pulled up for them for past codes. Anyone know why my AT light would flash then the next day not have any codes to pull up? The MAP sensor code that was coming up ended up being that the sensor was unplugged. I also changed the plugs and wires using NKG plugs and Duralast wires and reset the check engine light. Drove around for 10mi and no light back on yet. The plugs were pretty dirty and the one in the back right was really dirty and was really hard to screw out (why that would be?). Could bad plugs and wires resulting in a misfire really be the problem with the transmission and engine symptoms I posted about?

#10 grossgary

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Posted 04 April 2014 - 10:01 PM

Great news. Good work getting that stuff done. It may be that the sensor not plugged in was the issue and it's repaired now.

 

1996 doesn't have a MAP sensor - so is it a TPS, MAF or something else?  Can you post the exact code? 

EJ22's didn't have MAP sensors until 1999.

 

AT flashing means there's a code.  no flashing, no code.  you'll strike out if the light isn't flashing.

the secret handshake is a debacle, a real quack made that #()!*$!$!! up.  i've never gotten it to work, but plenty of others have.

Any 1995-1998 procedure will be the same as yours...and probably others.

 

I've never seen a knock sensor or misfire cause trans codes and i've seen gobs of those.  I've never seen a MAF cause one either but I've only ever tried to run a car a very few times with a MAF disconnected.

 

*** Find the list of TCU codes for your vehicle.  see what engine related sensor/codes are on the list.

 

You may want to chase those spark plug threads with a spark plug thread chaser in the future, that will allow them to turn smooth of butter.  Load the chaser up with grease to capture any particulates.


Edited by grossgary, 04 April 2014 - 10:03 PM.


#11 cascadeclimbn

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Posted 04 April 2014 - 10:07 PM

Alrighty so drove around some more and check engine light came back on and during this same test drive I had the acceleration issue again at higher speeds (50-65) on a slight incline (as has been the case every other time) where the rpm's would go up if you cranked on the gas pedal but the car still wouldn't go and lost speed. Happened on the freeway this time (a bit sketchy). This time I threw it in 3rd and kept chugging along at about 30mph till I coasted the hill and put it back in D and it started accelerating fine but with rough shifting. Took it to autozone had the check engine light read again and 2 of 3 codes stayed gone, the MAP sensor issue is resolved, and it seems as though I resolved the misfire issue with new plugs and wires. The only code pulling up still is the knock sensor. I've been reading around online and it sounds like several other folks have experienced the exact same acceleration and shifting issues as me and it's been the knock sensor's fault. So I'll replace that this weekend and hopefully all will be well.

#12 grossgary

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Posted 04 April 2014 - 10:28 PM

yes knock sensor will retard timing and acceleration and power will be non-existent. if it's bad enough the car can be almost undrivable. when you remove it - you'll notice significant cracking of the rubber encasement almost every time.

 

Knock sensor won't cause AT flashing or "rpms to risk without increasing speed" as described first post - unless that meant downshifting which might feel odd/different with that sensor cracking out.  working on cars with just typed words is tricky business!

 

isn't that series of procedures for reading the AT light a comic sketch!?!?!?!?  were you cussing or laughing?  lol

 

a 96 impreza has a MAF, not a MAP which comes in 99 impreza's.



#13 Gloyale

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Posted 06 April 2014 - 01:34 PM

a 96 impreza has a MAF, not a MAP which comes in 99 impreza's.

 

96+ EJ22 has both.

 

MAP is right behind MAF and air cleaner..........and there is a Solenoid that switches between atmosphere and intake pressure and the computer compares.

 

Doesn't have anything to do with shifting/trans issues.

 

Hate to say....but that trans is toast.


Edited by Gloyale, 06 April 2014 - 01:35 PM.


#14 cascadeclimbn

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Posted 06 April 2014 - 03:15 PM

96+ EJ22 has both.

MAP is right behind MAF and air cleaner..........and there is a Solenoid that switches between atmosphere and intake pressure and the computer compares.

Doesn't have anything to do with shifting/trans issues.

Hate to say....but that trans is toast.


Well I replaced the knock sensor yesterday and resolved the last of all the codes, reset the check engine light, drove it around for 50 miles, up and down hills at high and low speeds and no return of check engine light and no problems with loss of acceleration and hard shifts. So maybe it's not the transmission and it was in fact the knock sensor emulating "tranny" problems before. I've read a lot of posts on the internet of people having the same acceleration issues and replacing the knock sensor fixed the problem so I think the knock sensor can affect the transmissions performance or at least cause engine problems that make me think the trans is performing poorly. Guess I'll find out in the next few hundred miles.

#15 cascadeclimbn

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Posted 06 April 2014 - 03:26 PM

grossgary, my 96 does have a MAP sensor. The code was P0106. Ended up being that it was just disconnected.




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