1988 1.8L EFI $1000 college car backfires...need help!

[pmf]

alt.autos.subaru suggested I post this here as expert help is needed!

 

My son decelerated to a stop light and then according to him, when he tried

to accelerate the engine started missing and would not go at all. When I

towed it home, I removed the r/h timing belt cover to find a shredded belt

which I replaced along with the other side. The motor behaved to the best of

my recollection, about the same as it did the night we towed it home. Had a

mechanic friend come over and we did compression checks (ok), timing

re-checks (ok), all of the things one would normally think of (ok). The

distributor was a little loose so I replaced that with no change at all. The

symptoms are:

 

a.. rough idle (or none)

b.. starts up as though it's flooded (full throttle needed)

c.. vacuum oscillates wildly at any speed (it uses the full gauge) except

when fully loaded and then it's at near zero

d.. backfires through the carb. at all times except when fully opened up

e.. changing ignition timing while running make very little difference

 

Does this sound like a blown head gasket and if so, how does one diagnose

that? (the compression check showed between 120-140 on all cylinders.

 

Thanks in advance,

 

Peter

[GeneralDisorder]

Your timing is off.

 

Do a search in this section of the forum for the proper porcedure. You have to have the cams rotated 180 degrees from each other, and make sure you are using the valve timing marks and not the ignition timing marks on the flywheel (there are two sets of lines).

 

Also with the timing off, you cannot accurately check the compression since the valves are not opening and closing at the correct times.

 

GD

[WoodsWagon]

Valve timing is off that is. If the ignition timing is right, then you know you only got the passenger side belt on the wrong spot.

[Snowman]

Another vote for cam timing being incorrect. It's easy to screw up...happens to the best of us.

[NorthWet]

To clarify somewhat what the others have said, the timing belt installation instructions in some manuals don't always make it clear that after you have installed the distributor side belt (aligning the flywheel to the centermost of the 3 closely adjacent marks), that you then need to rotate the crank 360 degrees before you time the non-distributor side belt. The non-disty-side cam needs to be 180 cam degrees from the disty-side cam; when both belts are properly set, one has cam-sprocket timing mark up, the other has that mark down.

 

After you have set the belts (including setting the tensioners) rotate the engine a couple of times and recheck that the marks all still line up.

 

Another issue with setting the ignition timing: The engine control unit (ECU) adjusts the effective timing, and MAY try to do this while you are trying to set the ignition timing. The way to prevent this is to connect the single-wire green connectors that should be up by your winshield wiper motor (assuming that your EFI is single-point (SPFI) and not multi-point (MPFI)). These are diagnostic-mode connectors, and will halt the ECU from mucking about with timing while you are trying to set it; just remember to unplug these when you are through.

[Phizinza]

We had a EA82 running with the timing belts off by 3 and 4 notches.. (due to a lack of reading the manual properly) It ran, but didn't want to go anywhere. I say, read the FSM about 12 times, change the belt position about 3 times and you'll figure it out.

 

(Oh, I love my EA81 push-rod engine )

[pmf]

Thanks sooooooooooo much everyone! And especially to Pat for that very detailed explanation. You know, I followed the instructions in the manual and it did say to do the 360 rotation prior to installing the r/h belt but it never said anything about the timing mark orientation being 180 degrees opposed. In fact the pictures showed them both up. I probably thought it was just to take out any backlash and so did another rotation to line up the marks, does this seem likely? So just to clarify; I should see the cam timing mark on the dist side up and following a 360 degree crank rotation it will now be down and then I put the non-dist side belt on with its cam timing mark up. Is this correct?

[hooziewhatsit]

So just to clarify; I should see the cam timing mark on the dist side up and following a 360 degree crank rotation it will now be down and then I put the non-dist side belt on with its cam timing mark up. Is this correct?

 

Yep, have both cam 'dots' up to begin with. Put the drivers side belt on, crank the engine over Once, then put the passenger side belt on. The cams are now 180* from each other.

 

oh yea, may want to verify the distributor position also, to do this, get both belts on, then crank the engine so the passenger side cam dot is point NorthWest. At that point, the rotor should be pointing to the #1 plug on the cap (closest to the hill-holder spring/master cylinder)

[pmf]

Alright, me thinks that’s the problem! I’ll take it back apart tomorrow and post the “favorable” results. Thanks again, this is my first post on the group and I’m truly grateful to you all!

[Cougar]

Welcome to the forum. Hope you get it going again like it should be.

[86ruguy]

im a little slow but the cam timing "THING" happened to me:banghead:took me 2 days to figure it out:-\

thankfully i have friends in low places

[Meeky Moose]

double check the sirtributor as well.. had my ea82 running almost 180 out.. got 34mpg though lol thinkin about turning it back cause its less mpg with it in time correctly.. go figure

[pmf]

Well, you were all correct…it was indeed the failure to rotate the crank 360 ONCE! It’s all back together now and running like a champ. Thank you, Thank you, THANK YOU!!! This has got to be the best group online. This is in fact my first Subee but will not be my last, I’m hooked!

[Cougar]

We got another one!