subaru blow off valve check engine light

I modified my oem blow off valve to vent to atmosphere just too see if i like the result. I have a check engine light on after a few hours of running my car in this configuration. Is this common with all vta-blv's?. i plan to restore my car to oem spec. asap and i hope this will fix the problem. any info will be nice. hjbunger.

Reply to
howard B.
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Reply to
Tony Hwang

Take a valium! You're giving us Western Canadians a bad name with responses like this. Somebody piss in your cornflakes this morning?

Lots of people like to tinker... that's how things improve over time.

A blow-off valve is not "emmision stuff". It is there to relieve pressure in the intake manifold on a turbo engine after a sudden throttle closing to prevent damage to the compressor and other intake tract components. It will cause a momentary rich condition on gear change if vented to the atmosphere instead of back to the turbo inlet hose downstream of the MAF sensor. Why would you assume Howard was not going to "rewrite the firmware" through one of the currently available ECU re-flash systems offered by ECUtek or Cobb's AccessECU?

Spud.

Reply to
Spudster

Reply to
Tony Hwang

Guys, thanks for the info, rewrite the firmware?. whats that like?. well i re installed the BLV to JDM spec and now i have a quite car again. i like that better, but still the CE light persists. My partner who has a 2002 sonata gls v6 says that the computer will clear out after 20 starts. is this true?. OH and yes i dont know anything about anything so be gentle with me and type slow, ha ha.

Reply to
howard B.

Hi, Probably that meant, incident log clearing. It can't hold indefinite number of incidents due to size of memory. If you want to reset the ECU, just remove battery NEG cable for a few minutes. It'll reset and relearn everything. Hope CE light goes off too. Tony

Reply to
Tony Hwang

Well - the problem with venting to atmosphere with a BOV on a WRX, rather than maintaining the OEM diverter valve setup is that WRX is a MAF controlled car - the ECU meters the fuel which is delivered based upon how much air has passed through the intake - when you run a BOV, you are venting some of that air, but the ECU is not aware of it, so it still delivers fuel based upon how much air it has seen pass the MAF - as a result, the car will run rich under situations when the BOV vents - now, in normal driving, that probably doesn't mean too much - you just dump a little extra fuel through the system now and then - probably won't cause any problems. However, the harder the turbo is working when you shift, the more air which is vented, and thus the richer the car runs - raw fuel will make it into the exaust stream, and the first thing it hits is the catalytic converter in front of the turbo (in the up-pipe) - some will also make it through to the other cats - the raw fuel makes the cats increase in temperature, and can kill one (they generally melt down and disintigrate... not a good thing if the one in the up-pipe does that...

Anyway - the CEL could be anything from cat ineff. to an overtemp on something - get the code pulled. (I seriously doubt you hurt anything after a few hours)

There are really only two reasons to add a BOV - either you are running a higher boost than the stock diverter valve can handle (somewhere around

19psi, from what I have read) or you really like the sound a BOV makes (they usually route the air through a whistle of some sort, so that they make lots of noise) and don't care about potential damage to the system.
Reply to
David & Caroline

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