1994 Subaru Justy Backfire

Tiny
MRRUBBURN
  • MEMBER
  • 1994 SUBARU JUSTY
  • 2.0L
  • 3 CYL
  • FWD
  • MANUAL
  • 300,000 MILES
I recently cleaned the engine of oil and coolant with petrol and a rag, so I could see where it is exactly leaking from, turns out it is the head gasket needs changing. To get a better look and to get access for cleaning I removed the filter, top cover,
distributor, crank shaft pulley and timing belt cover. After I was done cleaning and inspecting, I put everything back where it was, started it up and went back home and parked (car was running great)
The next morning it cranked didnt start at all!

So I thought that something was wrong with the dizzy and took it apart and set it just right, changed spark plugs and set the gap. Still nothing! So I grabbed my timing light gun to see if the leads were getting spark, and they were. I pulled out the spark plug and cranked, there was a healthy spark.
Then I thought the distributor lost its timing so I just rotated it (advanced). The engine fired 4 or 6 six times and stalled. I gave it a bit of gas to help keep it running @800rpm so I could adjust the timing to 5 BTDC.
When I put the mark on 5 BTDC (found on crankshaft pulley) with timing light, the engine started pinging hard and often stalled. So I thought lets get the engine to rev as high as possible at idle by rotating the distributor (advance). I started advancing and sure enough the pinging went away and rpms got at 1100, so I backed off the idle back to about 800rpm, I found that the distributor almost couldn t be rotated anymore and my timing light was reading about 60 BTDC on the crank pulley.
I let the engine warm up and tried to put it to 5 BTDC again, the idle dropped to about 600rpm and the pinging was that obvious this time, but when I put my foot on the accelerator, the car backfired straight through the carb! I set the timing back to 60 BTDC and the engine was sounding great and healthy, foot on accelerator and redlined it with no problems at all.
So I thought maybe the timing belt slipped a tooth. I checked the timing belt and it was exactly right (checked with another exact same engine on another Subaru J10 that has no problems). Then I figured to just swap the dizzy with the other J10. The other J10 started right up, so there were no problems with the dizzy. I put the other J10 s dizzy on my car and still everything remained the same.
The crankshaft pulley and dizzy can only go in one way, even the contact breaker camshaft, rotor and cap.
What else could there be. This is very frustrating because I never encountered anything like this, it sound physically impossible. (I am very well mechanically inclined with this engine) Any thoughts. Pls helpT

Thanks
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Saturday, November 21st, 2015 AT 4:47 AM

5 Replies

Tiny
MRRUBBURN
  • MEMBER
A few corrections. The engine is a 1.0 liter 3 cylinder!
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Saturday, November 21st, 2015 AT 4:52 AM
Tiny
CJ MEDEVAC
  • EXPERT
I CANNOT FIND ANY INFO FOR YOUR VEHICLE IN THE REFERENCES AVAILABLE TO ME.

JUST THROWING STUFF AT YOU

IS THERE A VACUUM ADVANCE OR A SPOUT CONNECTOR TO THE DISTRIBUTOR THAT NEEDS TO BE DISCONNECTED (OR PLUGGED OFF) DURING THE TIMING PROCEDURE?

THE CRANKSHAFT PULLEY YOUR MARKS ARE ON, IS THIS ON THE HARMONIC BALANCER (VIBRATION DAMPER), IS IT POSSIBLE THAT THE INNER PART OF IT HAS SLIPPED, THUS MAKING THE TIMING MARKS ON THE OUTER PORTION BE IN THE WRONG POSITION NOW?

DO YOU HAVE A PLAIN JANE TIMING GUN OR AN ADJUSTABLE ONE? I'VE NOTICED THAT MANY PEOPLE WANT TO ADJUST THE GUN (OFF OF ZERO) WHEN THEY ARE PERFORMING A TRADITIONAL, RUN OF THE MILL, TIMING CHECK. I TRULY BELIEVE THAT THEY THINK THE GUN WILL TIME IT FOR THEM!

THE MEDIC
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Saturday, November 21st, 2015 AT 6:28 PM
Tiny
MRRUBBURN
  • MEMBER
Thanks for your reply but,

I swapped the distributor from a good working car and still nothing,
I tried it with the vacuum hose and without it, still nothing.
Yes my timing gun is adjustable because when I align the crank pulley mark to 0 the gun says 60 BTDC and the engine runs great, even better if I adjust it to 55 BTDC.
The harmonic balancer has nothing to so with the ignition, it is connected to the oil pump and water pump by chain. Even if the harmonic balancer has slipped it would only have vibration issues not ignition backfire issues.
Am I right? You should note that when I try to put to 5 BTDC the plugs dont always get spark. But when they do the engine runs like a sick camel.
The only thing to keep in mind is this.
How is the engine working great at 60BTDC?
And why did it happen overnight?
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Sunday, November 22nd, 2015 AT 2:08 AM
Tiny
CJ MEDEVAC
  • EXPERT
MAYBE THIS WILL HELP

CLASS 1

www. Youtube. Com/watch?V=5a2X9mSSlQY

CLASS 2

www. Youtube. Com/watch?NR=1&v=FHX1yXVyIMg&feature=endscreen

PIC OF MY BALANCER BELOW, THE KEY WAY FOR THE CRANK AND THE TIMING MARK ON THE OUTER RING ARE SPACED AT A CERTAIN DEGREE APART (WHICH I DON'T KNOW) BUT YOU CAN COMPARE POSITIONS BY LAYING A NEW (KNOWN GOOD) ONE OVER ONE IN THAT IS IN QUESTION.

THE ONLY OTHER EXPLANATIONS I MIGHT OFFER IS

(IF IT HAS) A MECHANICAL ADVANCE MAYBE THE SPRING(S) BROKE

YOU ARE TIMING OFF OF THE WRONG PLUG WIRE

YOUR TIMING INDICATOR MAY BE FROM ANOTHER VEHICLE, WHOSE POSITION WAS DIFFERENT OR EVEN A DONOR HARMONIC BALANCER FROM ANOTHER VEHICLE.

ARE YOU 100% SURE OF THE TIMING MARKINGS, THERE'S NOT ANOTHER NOTCH ON THE PULLEY?

JUST SOME THOUGHTS

IF IT WORKS, AND CORRECTLY, GREAT!

THE MEDIC
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Sunday, November 22nd, 2015 AT 5:41 PM
Tiny
MRRUBBURN
  • MEMBER
I cant see how im not being clear.

The vacuum advance is ok because I swapped the dizzy with a good working one from another identical car, and I put mine on the other car and it ran fine.

There are 6 notches in total on the crankshaft pulley, a notch for piston 2 TDC another for piston 3 TDC and a 0, 5, 10, 15 degrees mark notches with 0 being the TDC of piston 1.

I always plug the timing gun to the number spark plug so I know its correct.

The timing indicator is the crank pulley, now. If it was showing 5BTDC and was working perfectly, why would the car work perfectly on 55BTDC the next day.

I lined up everything the same as I have in my other good working car.
That one runs great, mine doesn t.

I asked a lot of mechanics. They are baffled!
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Monday, November 23rd, 2015 AT 7:17 AM

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