Basically.... About 3 weeks ago car was intermittent no start. Cranking was rough/rumbly and gas pedal hadda be teased in order for it to sometimes start.

Attached a missing ground strap and car was reliable for a few weeks. Still had a bit of a rough/rumbly start but at least started and drove. It ran fine, but I pulled the motor for HG job and no spark after re-install.

Tested coil pack resistance, tested bad. Swapped coil pack....didn't help. Power to coil pack, no signal to coil pack. Crank sensor & cam sensors pass resistance tests. Checked wiring to ECU, passed. Reinstalled ECU, engine started and ran for 15 seconds including idling and revs but no issue was actually solved... But we reinstalled accessories. Again, no spark, no signal to coil. Fuses tested/examined, so not a fuse.

It's a 2001 Subary Legacy Outback 2.5/EJ25. Any advice on what might be going on or how to test the ECU would be great help.

May not be the "best" way to test an ECM, but the most practical way for mere mortals to do it is to swap in another one and see if anything changes.

I take it you're not getting any error codes?

 

^^^ yeah scan for pending codes, note them,  get freezefraome data if possible, clear them, try to start, scan again to see what comes back immediately.

 

some things on that year model that 'might' cause no/rough start issues; IACV hose at the intake tubing end loose, cap/o-ring problem on fuel pump, moisture (or oil form leaky VC gaskets) on old plug wires/boots, flooding from several no-start tries (or possibly bad engine temp sensor) , mist-timed crank/cam timing.

double check cam/crank timing belt timing. Check IACV hose. Try starting with gas pedal HELD all the way down while cranking (that signals the ECU to shut off injectors. it's the 'clear flood' procedure) - or, pull plugs to look for fuel wetness.

I know you said you're missing spark but, you could try starting with starter fluid.

it does seem like you 'could' have some ground or other electrical issues.

 

Edited January 7, 20197 yr by 1 Lucky Texan

10 hours ago, jonathan909 said:

I take it you're not getting any error codes?

Nope, no codes. The car has to be running to get any codes (at least, with the scanner we have). 

3 hours ago, 1 Lucky Texan said:

Some things on that year model that 'might' cause no/rough start issues; IACV hose at the intake tubing end loose, cap/o-ring problem on fuel pump, moisture (or oil form leaky VC gaskets) on old plug wires/boots, flooding from several no-start tries (or possibly bad engine temp sensor) , mist-timed crank/cam timing.

double check cam/crank timing belt timing. Check IACV hose. Try starting with gas pedal HELD all the way down while cranking (that signals the ECU to shut off injectors. it's the 'clear flood' procedure) - or, pull plugs to look for fuel wetness.

We've checked the timing and it all checks out. We've held the gas pedal all the way down and it still just cranks. But today I will definitely check and re-check what you've listed. Thanks for your input! 

should be able the scan codes from key ON .

if it fires with starter fluid, next check is probably fuel supply; https://www.subaruoutback.org/forums/110-gen-2-2000-2004/41182-symptoms-fuel-pump-o-ring-problem.html

Are you positive the ground on the intake manifold is clean and tight? It's the ground for the ecm. I've seen people (unnecessarily) remove the wiring harness from the intake manifold, so overlooking that ground can cause your problem. Do you smell raw fuel from the tailpipe after cranking it for a while?