Help, No Spark!!

[SPADE-27]

Hello, first off Id like to introduce: Newbie in Illinois, first thread.

 

I have a 1993 Impreza 1.8 and have no spark on only 2 plugs. I have changed the ignition coil and module. Is there a better way to check this instead of just replacing parts? any ideas what it could be?

[johnceggleston]

Hello, first off Id like to introduce: Newbie in Illinois, first thread.

 

I have a 1993 Impreza 1.8 and have no spark on only 2 plugs. I have changed the ignition coil and module. Is there a better way to check this instead of just replacing parts? any ideas what it could be?

 

when you say no spark, how did you determine that?

 

which 2 have no spark? front, rear, left or right?

front or rear would be a coil problem, left or right could be a timing belt problem.

 

try swapping the plug wires from no spark to yes spark to see if the problem follows the wire or stays with the cylinder.

[SPADE-27]

Its the two rear plugs. Ive replace the coil and changed the wires with no change...?

[OB99W]

Hello, first off Id like to introduce: Newbie in Illinois, first thread.

Welcome to the forum.

 

 

[...]I have changed the ignition coil and module. [...]

By "module", are you referring to the igniter? If so, did you get a new one, or is it used?

 

 

Is there a better way to check this instead of just replacing parts?

Do you have a voltmeter, and know how to use it? If so, we can probably provide some troubleshooting info.

 

 

any ideas what it could be?

There are a few causes. Although rare, it could even be a failure of the ECU. However, let's not go there until we rule out more-likely culprits.

[SPADE-27]

I replaced the igniter with a used one. I do know how to use a voltmeter and have one. Any help would be appreciated.

[OB99W]

I replaced the igniter with a used one. I do know how to use a voltmeter and have one. Any help would be appreciated.

Igniter failure is a common cause of only one of the two coils in the pack operating, and a used igniter might have the same failure.

 

See http://www.endwrench.com/pdf/elec/FtIgnitionDiagOpS00.pdf .

(There are errors in that info. In the "Ignition Coil Testing" section, the terminal numbers listed are reversed between the primary and secondary -- the low resistance readings should be for the primaries, the high ones for the secondaries.)

 

Do the tests on the last page of that PDF. In particular, see if switching is occurring at both coil pack primary terminals. If not, then check if the igniter inputs are getting switching from the ECU.

 

If the ECU isn't switching, check the cam/crank sensors for output (and examine the reluctors, if there's reason to suspect physical damage).

 

If you need pinout info, let us know.

 

EDIT: The 1992 FSM at http://www.main.experiencetherave.com/subaru_manual_scans/ might help -- see page 300 (of 335) of the PDF for a wiring diagram that should be close to what you have.

Edited May 5, 2010 by OB99W