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Low Idle after panel filter?


ONRAMP

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So over the last two weeks, I decided to hold on to my LGT, and subsequently decided to start messing with it (was bone stock).

I took the silencer off the airbox. Nice little bit of extra growl from 3-4k. No problems.

Put in a Perrin drop-in air filter element. Little more woosh/pfft. No problems.

Two days after putting in the Perrin, I get a CEL. Have a shop pull the code, P0171, running lean. Inspected my connections, looked like the intake hose was off just a bit, and might be sucking some air where it hooks to the airbox. Re-attached the hose and had the shop clear the code, and so far, so good. The CEL isn't back, but the idle seems very low, and on a couple of occassions, it has almost stalled and caught itself. After I cleared the code, I also had trouble starting the car. On the third try, it fired just like normal, and hasn't had any problem since.

Any thoughts? I searched around for idle/intake related problems, and didn't find anything. Any specific search I should have tried?

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After clearing the code, resetting the ECU, or re-flashing, you'll get the "long cranks." That's normal. :) Typically, with the exception of the very first crank, waiting 'till after your gauges complete their start-up sweep, on the second crank attempt, will get you fired-up every time, though.

 

Definitely check your hosing and MAF electrical connections again, as well as how the panel is seated in the airbox. It "sounds" like you might have a leak that the ECU is trying to deal with, thus causing the unstable idle.

 

Also, it'll take a little bit of time and driving for your ECU to re-learn its baseline stability.

<-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges

'16 Outback, '16 WRX, 7th Subaru Family

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After clearing the code, resetting the ECU, or re-flashing, you'll get the "long cranks." That's normal. :) Typically, with the exception of the very first crank, waiting 'till after your gauges complete their start-up sweep, on the second crank attempt, will get you fired-up every time, though.

 

Definitely check your hosing and MAF electrical connections again, as well as how the panel is seated in the airbox. It "sounds" like you might have a leak that the ECU is trying to deal with, thus causing the unstable idle.

 

Also, it'll take a little bit of time and driving for your ECU to re-learn its baseline stability.

 

I drove it a block from the shop where I had the code reset, and aside from the idle, it felt fine, and fired up quickly when I left the office an hour later, so that makes sense.

 

I drove about 6 miles home and 6 back to the office this morning, and the idle still feels low. I'll keep an eye on it and see if it adjusts. I've checked all my underhood fittings, and all seems to be tight. I'll look at it again later, and may R&R the filter element and make sure nothing is caught in it or pinched.

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Is this a case where there is too much oil on the filter and its messing up the MAF?

 

Wouldn't that throw a different fault code? I tried to clean off the excess before I put it in. It wasn't as oily as I expected it to be.

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so weird. this is the 2nd or 3rd thread on panel filter problems I've seen today
"Barack Obama, mothaf#%@a! Barack Obama! I'm the president...of hittin' the ass!" -this is not a political view it's merely a quote from a hilarious tv show.
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The CEL is back! I'm going to take everything out and put it all back together. From what I can tell, I have an air leak somewhere. Wife has the car today, so tomorrow will be the day.
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:(

 

OK, logically, if you have a leak, it should be associated with the intake tract - since this is where you took the assembly off the vehicle to do the silencer/resonator removal.

 

Work backwards from the very end of the intake tract (i.e. at the filter). Check all connections. Also check the vac. hoses over by the right (passenger's side) "front" of the intake manifold. It's possible that these could have come loose from removing the cosmetic engine cover - same story with the BPV recirc hose.

 

Don't forget to check connections that use the worm-drive clamps, too! :)

<-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges

'16 Outback, '16 WRX, 7th Subaru Family

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Don't forget to check connections that use the worm-drive clamps, too! :)

 

That's where I thought it was coming from the first time. Went back in and checked those specifically, and thought that had fixed it.

 

But that's what the plan is at this point. I'm going to go back to where I started changing things. Hope I can figure out whereI went wrong.

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Is this a case where there is too much oil on the filter and its messing up the MAF?

 

Rookie mistake. For future reference, Perrin filters come VERY HEAVILY OILED. I thought I got all the excess off before installing, but I was mistaken.

 

Seems the cause of all my problems was indeed oil on the MAF. Took the airbox out today and cleaned off the MAF with contact cleaner, mopped up the oil in the box, and tried to get as much excess oil off the filter element itself before re-assembling. That did the trick. CEL went off by itself, and she's running like a top.

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Rookie mistake. For future reference, Perrin filters come VERY HEAVILY OILED. I thought I got all the excess off before installing, but I was mistaken.

 

Seems the cause of all my problems was indeed oil on the MAF. Took the airbox out today and cleaned off the MAF with contact cleaner, mopped up the oil in the box, and tried to get as much excess oil off the filter element itself before re-assembling. That did the trick. CEL went off by itself, and she's running like a top.

 

Glad to hear that you solved the problem, that's why I went with the blitz drop in filter .. no oil needed :)

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Good to hear that you tracked down the problem and solved it! :D

<-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges

'16 Outback, '16 WRX, 7th Subaru Family

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^ No, not at all! This is a common thing! Don't sell yourself short, bro! :)

<-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges

'16 Outback, '16 WRX, 7th Subaru Family

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Not a rookie mistake - don't be hard on yourself. A lot of us with "oiled" filters have made that mistake at one time or another. It comes with the territory.

 

SBT

- Pro amore Dei et patriam et populum -
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