99 Impreza OBS, will not run after smog check, need help

[Natedoc808]

Hey Subie forum members,

thankfully it has been a long time since I've needed your help, however this is serious.

 

I took my car in for a smog check (in CA) two days ago, no she will not run. Need help. Full sequence of events below.

 

2 days prior to smog check: attempted to pass with aftermarket intake on car which did not pass component check but emissions were beautiful, 10-15% of allowed limits. 

 

Removed aftermarket intake and replaced with stock dual filter setup and all PCV hoses routed accordingly, didn't remember to disconnect battery to reset ECM.

 

Drove for two days, minus a few HP, with no CEL or performance issues. I have a A/F ratio gauge in the center of dash (removed dash compartment) which showed typical readouts with needle bobbing in optimal range during cruising throttle positions, rich when I stepped on it and lean if i cut throttle until idle stable then bobbed optimal again.

 

Smog Check: take it into local full service shop (reputable both by report of others and historically as they have aligned many of my cars and done exhaust work). it took about twice as long as usual but I believe they ran it twice just to make sure of the result.

 

It failed emissions as gross polluter with excess hydrocarbon (unburned fuel) at idle only, 2500rpm test was still clean as a whistle. I get back in my car and fire it up and let it idle and low and behold the A/F gauge is nearly pinned rich. Nearly pinned as in way higher than I can get it to go by stomping the throttle under full load up a steep hill. But no CEL.

 

I plugged in my code reader and cleared the DTCs just as a precaution, checked live data for any clear signs of sensor failure but all looked good.

 

I opened intake and checked to make sure no obstruction was lodged in the intake, checked MAF connections, checked PCV system, checked intake for leaks, checked injectors for leaks- all were clear. 

 

I pulled out the primary filter without resetting the ECM to attempt to trick it into leaning out a little, took it for a test drive with no luck. Pulled the secondary filter right near the throttle body and it wouldn't run. Reinstalled the secondary filter and it ran but still rich at idle like before.

 

Cleaned MAF with MAF cleaner, let dry 5 min, reinstalled. 

 

CURRENT BEHAVIOR: Now car will not idle, can start it fires up to 1500 for about 2 sec then stalls out like but i can keep it going by pummping the gas and rev it up to 3-4k rpm, then if I hold the throttle at that position it will hold for roughly 5-10 seconds then drop off to stall unless I pump it back up, and repeat the dropoff to stall in 5-10 seconds.

 

Thought I may have fried the MAF by not letting it dry, replaced, reset ECM, same status as above.

 

My first thought is- WTF did these guys do to my car?! What are the next steps I should take?

 

Check fuel pressure? (where is the valve?)

Electronics? 

 

Any help is appreciated. Thanks 

[1 Lucky Texan]

IACV hose may have dropped off the intake tubing. Not sure though - and may not explain the rich condition....

 

odd, I'd triple check everywhere I worked, everywhere they poked around during the test for hoses or wire connection loose - including grounds.

 

might be worth checking cam/crank timing. did you scan for pending codes?

[Natedoc808]

Scanned for codes- no codes present. 

[Natedoc808]

So, results in: monkeys at the smog station must check that both filters are in place prior to checking emissions, didn't properly secure/close the airbox on the tabbed/hinged side (blind side) on either so it was pulling a ton of air in and thus the MAF told the ECM to rich up the mixture because so much air was coming in!!! 

SO will be fun to have the conversation with this shop in the coming week!

[1 Lucky Texan]

but, it's still metered air - I guess it throws the whole airflow off-kilter enough to fool the MAF?

 

glad it's back to normal.