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Troubleshooting an EA82T Engine


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31 replies to this topic

#1 James_Ford

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Posted 16 September 2013 - 02:19 PM

I just purchased my first Subaru - a lovely project car with an '86 EA82T Engine.
The previous owner had experienced a timing belt failure and had replaced the water pump, thermostat, timing belts, plugs and wires, and 'some hoses' (radiator) and once it was back together, it had no power and would overheat quickly.


That's when he decided his head gasket was blown and sold it to me.


Well it "runs" - after a fasion. It will run rough, stumble, backfire, and die within a few seconds of being cranked over unless you give it about half throttle, which will jump you to 3000 RPM where it runs... kind of smoother. Sorta.

From what I can hear my driver's side bank is running great, my passenger side is not. I'm headed back out to verify this by pulling the plugs out of one half of my engine, and then the other.

I don't think I have head gasket trouble. All cylinders are within a few pounds of 100 psi. This got me thinking valves and ignition timing

I've rechecked the timing, rechecked the distributor, even pulled the valve cover off the passenger side so I could see the cam timing for myself.

I am confident that I'm not a tooth off on either cam sprocket, and have verified that my distributor is pointing at the point for cylinder one when cylinder one is reaching TDC.

Where should I go from here?

I'm new to these engines, is there anything the P.O. could have done during the service he performed that would make it run like this?

Having checked compression and valve timing - it is probably spark or fuel... right?

Thanks for your help Subie friends.


Edited by James_Ford, 16 September 2013 - 03:10 PM.


#2 NorthWet

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Posted 16 September 2013 - 04:32 PM

The most common fault when replacing timing belts on the EA82 engine is to forget to rotate the crankshaft one full revolution before putting on the second belt.  If this is not done, then the non-distributor-side valves will be timed 180degrees off.  It will act like those cylinders are not producing power.

 

Remove the covers over the cam sprockets, and verify that the timing dots for the left and right cam are pointed 180 degrees apart.  If they are both pointed the same direction, then the rotation step was skipped.

 

Another common fault is caused by aligning the timing belts relative to TDC rather than the 3 "hash marks" on the flywheel.

 

It is also common to be off a tooth after releasing the tensioners.  This causes only moderate grief.



#3 James_Ford

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Posted 16 September 2013 - 05:47 PM

NorthWet,
I was convinced that one of those common things would be my problem, too. 

But I've checked the belt install six different ways - even took the valve cover gasket off to visually verify that my valves were opening at the right time (or at least not way off)

Everything checks out.
 

So why the hell is half my engine not working right?
 



#4 NorthWet

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Posted 16 September 2013 - 06:49 PM

The "Gold Standard" is to look at the timing marks rather than the valves.  Being able to state with assurance that one cam-sprocket mark was straight up and the other was straight down while the case pointer was on the middle 3 of the hash marks avoids a lot of confusion.

 

So, another possibility is mixed up spark plug wires, or bad wires.



#5 James_Ford

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Posted 16 September 2013 - 09:36 PM

Oh, I've checked the hash marks twenty times.
Spark plugs and dizzy are correct as far as i know but I'll triple check it tomorrow.
Wires are new.

Engine smells really rich when I'm trying to run it.

What kind of ignition problem would only affect one cylinder bank?


...intake manifold gasket?


Edited by James_Ford, 16 September 2013 - 09:36 PM.


#6 rain_man_rich

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Posted 17 September 2013 - 11:29 AM

Look at the wiring harness by the battery.  Is it all loose and laying down on the battery plate?  If so, it can wear through to the wiring and cause some of the problems you are describing.



#7 86 Wonder Wedge

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Posted 17 September 2013 - 11:54 AM

I'd also make sure your injectors aren't stuck or damaged. You could also unplug the MAF and then see if it runs any smoother..

 

Do you have a timing light? Put the light on each plug wire (closer to the plug the better) and make sure you get a steady, bright flash (the actual timing isn't important in this test) to ensure you are actually getting good spark consistently. You could have a bad/poor CAS...



#8 MilesFox

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Posted 17 September 2013 - 12:52 PM

It's possible that the ignition wires are routed incorrectly if you have backfiring out of the throttle. Firing order is 1-3-2-4. #1 cyl is the passenger side front, 3 behind it, #2 is driver front, 4 behind it.

 

Follow the "Timing Belt Procedure" to be sure

 

and the ignition sequence:



#9 NorthWet

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Posted 17 September 2013 - 01:11 PM

Look for problems that are related to work that has been done.  Look for simple problems before looking for exotic problems.  99% (made-up stat, but close to reality) of issues of this type are either timing belt alignment (85%) or firing-order wrong due to swapped cables (10%).

 

Follow Miles/Fox's videos... good stuff.



#10 scoobiedubie

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Posted 17 September 2013 - 01:45 PM

The cylinders should all be over 125 psi, not 100 psi. Your reading could however be caused by the gauge that you are using. 86T's are problematic. I have one. The distributors go out. The hot wire to the alternator gets fried, brittle and breaks, and the last few inches need replacing every 10,000 miles. The capacitor by the coil goes out. The black fusible link goes out. The PCV valve gets clogged, which sounds like what the problem is. The distributor cap points need frequent cleaning off of the corrosion. A bad spark plug may also be the culprit. It needs a double core radiator. The radiator thermosensor/auxiliary fan switch goes out. It has too many heat shields that trap the heat around the turbo.

#11 scoobiedubie

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Posted 17 September 2013 - 01:52 PM

If you have vacuum line leaks caused from broken plastic nipples, it won't idle very well. You have two vacuum pumps on the right side of the engine. There is a lot of connections on top of the engine, that break easily. And then you have a vacuum line connection to the distributor.

Edited by scoobiedubie, 17 September 2013 - 01:52 PM.


#12 James_Ford

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Posted 17 September 2013 - 02:41 PM

It's ALIVE!


It runs now. However, it is very down on power - with dead spots at certain engine speeds / throttle positions. Throws a code 35 too but I hear that's common...

NorthWet, 


Spot on with looking for problems caused by previous work.
Studying the vacuum diagrams revealed a few problems to fix and it runs now.
I'm going to continue tracing vacuum lines to see if i can get it running better.

But again, the timing belt is installed correctly - the plug wires are installed correctly.

scoobiedubie, I'm at 7000 feet and the turbo version is only... what... 7.7 :1?
all four at 100 seemed good, given that. Thoughts?

MilesFox, your videos were among the resources I looked at to verify this. Distributor position, timing belts, and firing order check out.
They didn't when I picked up the car though. P.O. seemed to thing the distributor went clockwise...

 



#13 scoobiedubie

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Posted 17 September 2013 - 04:39 PM

Code 35 is "EGR solenoid switch fixed in On or Off position.

Solutions are: repair harness to solenoid, replace EGR solenoid or replace Control Unit

#14 scoobiedubie

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Posted 17 September 2013 - 04:52 PM

The solenoid is in the vacuum line system. It is a cube of about 1 inch on all sides, with two plastic nipples that break off real easily. It sits behind the thermostat housing and just to the right. It is beneath the shiny aluminum intake air gismo coming off of the turbo.

#15 MilesFox

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Posted 17 September 2013 - 07:16 PM

In regards to the distributor, the 86 should have an external knock control unit, the disty is mechanical, vaccuum advance, and is set to 20 deg BTDC. 

 

For future reference, the 85/86 mpfi are similar, but 87 and later MPFI is different with optical disty. The 85/86 mpfi is schematically more similar to the ea81t 83-84. 



#16 James_Ford

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Posted 18 September 2013 - 01:13 PM

And the winner is- Exhaust leak!

I already know I have a large and inconsequential exhaust leak just in front of the muffler - but I was starting to wonder if it was possible that I had one farther up on the exhaust. 

I sucked some Seafoam up and voila - lovely clouds of white smoke billow from the turbo area.

Another good use for Seafoam.

Looks like I will be tracking the problem down more and then hitting the classifieds...  


 



#17 NorthWet

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Posted 18 September 2013 - 08:49 PM

Common exhaust failure point is the uppipe cracks right at the turbo flange.  A pre-turbo crack will usually just make the engine feel down on power throughout the rpm range.  My experience is that peaks-and-valleys in power across the RPM range is usually a problem in the HT part of the ignition system (rotor, cap wires and plugs).



#18 James_Ford

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Posted 18 September 2013 - 11:23 PM

Well... My fingers are crossed. But I'm not that hopeful that fixing the leak will get me running well again.
But first things first!
It does appear to be at the flange.
Currently I'm waiting on the penatrating oil to soak into that pesky rearmost flange bolt so I can remove it. And also on daylight, I suppose.

#19 James_Ford

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Posted 18 September 2013 - 11:27 PM

Here it sits in front of the post apocalypse repair shop.
A leaky shed that was literally used to store garbage before I turned it into my no budget work space.Attached File  IMG_20130918_173027_283.jpg   114.66K   17 downloads

Edited by James_Ford, 18 September 2013 - 11:29 PM.


#20 scoobiedubie

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Posted 19 September 2013 - 12:10 AM

The EA82T cross-pipes tend to crack just below the bolted coupling to the turbo. The cross-pipes came in 3 sizes as measured at that crack. 1 1/4" ID, 1 3/8" ID and 1 1/2"ID. The smaller ones tend to crack sooner. The larger one has better power. None are available from Subaru. You might as well start hitting the wrecking yards now, or the Subaru mechanics who salvage Subarus. The crack makes the turbo worthless as the exhaust will not spin the turbo blades fast enough, or at all.

#21 NorthWet

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Posted 19 September 2013 - 01:42 AM

If you can weld, or know somebody who can, it is not that hard to fix the uppipe flange as it literally cracks-off at the pipe-to-flange joint, Hardest parts are being patient with the turbo bolts (it can be a real bummer if you snap one), and dealing with the spot-welded heat shield that shrouds the broken joint.

 

Is the wacky powerband RPM related or load/airflow related?  If load/airflow, a little less likely cause is a badly worn MAF:  Your MAF is a flapper-type that sometimes has the contacts wear through the resistive tracks. 



#22 MilesFox

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Posted 19 September 2013 - 12:26 PM

There is a chance i can source an up-pipe if you ultimately need one. There is a spare ea82 engien iat desmond's shop if he is not using it for the XT. I should make another video regarding removal and install of the turbo with it if it i there to take.



#23 James_Ford

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Posted 19 September 2013 - 01:54 PM

Yeah... The turbo bolts are a huge PITA.

Time to buy that MIG welder I've wanted for so long...

It does seem airflow related to me. The resistive tracks in my MAF look just fine.

I'm still working on taking the ERG out for cleaning however I'm waiting on the pen oil to do it's work on that, as well. It does click when I push on the diaphragm, so I don't think it's stuck open...

MilesFox,
The world could use more EA82 videos. 
I'm a Wisconsinite myself. Grew up in Minocqua.



#24 James_Ford

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Posted 20 September 2013 - 04:47 PM

Exhaust removal complete.
Removal of the heat shields was... yeah it was destructive.
MilesFox I think I will be taking up on that if it is available.

On the other hand, how asinine would I be if I repaired and reinstalled sans heat shield?[attachment=9759:IMG_20130920_154320.JPG]

Attached Files


Edited by James_Ford, 20 September 2013 - 05:00 PM.


#25 NorthWet

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Posted 20 September 2013 - 09:07 PM

That appears...ummmm... different to the 2 that I have repaired.  Is that at the turbo mount flange???  On my 87+ uppipes, it seems to me that was a straight shot from pipe to flange, while yours looks like a 90-degree bend.  I am soooo confused.

 

Looks like someone has messed with that joint before.






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