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Guest Message by DevFuse
 

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strrange star wars light saber sound

mass air flow sensor?

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2 replies to this topic

#1 davcartwright

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Posted 15 December 2017 - 09:49 PM

inherited a sucking draining lag in a 97 subaru legacy with the 2.2

thought maybe (first cold day low fuel) the fuel needed stabilizer added that to no avail

threw code at me so i took it to shop. code said not firing on the coil pack for two and four but car showed no signs that that was the issue. pulled plug wires from coil #1 was a little green and loose. cleaned packed with electro grease, moved to next code that was mafs cleaned it with electrode cleaner and reattached. brought car home from garage noticed occasional lagging like it was flooding or not getting proper burn mixture.

popped the hood to see w.t.f. and heard a strange sound over the low idling engine.

popped clips on the intake and the noise was much louder. like the sound of a powered up light saber in star wars or a flat low hum with some volume. ran back to the garage had the tester thrown to it again mech said it showed a 0 while in idle and it should show something, what reading exactly he was talking about i had no idea but the code showed m.a.f.s. and throttle positioning sensor.

took it home adjusted the throttle positioning sensor to idle up.

took it back to garage and had it hooked up again and that reading he was taking prior showed a 2.0 at idle. no idea what that meant be seemed to run fine and shift fine and the lagging was gone and the check engine light was out.

ran fine for a day or so but still made that humming noise.

then it really stated acting up after driving about two miles from hom. trying to cut out at every stop sign, then wouldn't start. adjusted the throttle position sensor again. ran ok for about a mile then began lagging and trying to stall out.

what is my best plan of attack?

my thought is replace the mass air flow sensor simply cause i can not think of anything that could make the trumpeting sound. but could it be simply the throttle position sensor? both show on code now.

i have never heard a sound like that before coming from the air intake. and no one i've spoken with (guys at the garage, a mech who has worked on subbies for forty years) has ever heard of this noise. i can not even think of anything in the air intake or throttle body that would make that sound. any thoughts or suggestions would be appreciated as chasing ghosts can be expensive.



#2 Fairtax4me

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Posted 20 December 2017 - 09:56 PM

Can you get a video of the sound?

Idle speed is not adjustable with the TPS. The ECU sets idle speed and it will correct itself to 750rpm regardless of TPS position, but adjusting the TPS will throw off the ECM load calculation and will throw off transmission shift points. Will cause more problems than that, but either way the TPS needs to be set back to its original position.

What are the codes?

#3 1 Lucky Texan

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Posted 20 December 2017 - 11:00 PM

any history on the car?

it occurs to me a cracked IACV hose could cause misfires, low idle and maybe a noise...?




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