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Low idle with cyl misfire


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Noob to the forum here, I did some searching here and didn't really find an answer so here goes.

Just bought a rebuildable 07 legacy limited got the body work all done and such ( I own a body shop ) it only has 60,000 miles after getting all back together and running after it warms up to op temp it appears as though the idle is lower than it should be mid 600 to low 700's I did a relearn and that didn't help.

Also after it warms up and I drive it for a bit if I'm stopped at a light it develops a miss and is always cyl no.1

Here is what I have done so far new battery terminals, new plugs, swaped no. 1 and 4 plug wires, miss stayed on cyl 1

Dumped some injector cleaner in the tank

I'm lost at this point and getting frustrated I know it's trial and error but not sure where to go from here and researching theses issues there's SO many could be's just thought I would see what your thoughts are

Sorry so long and thanks much

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After having the battery disconnected, how much time have you given the car to relearn? I've found that the car can take some time to fully relearn, and I'm wondering if the misfire will resolve itself after enough time.
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I've prob drove roughly 50 miles and prob 10 start ups, it does throw a cel for the misfire just wanted to clarify that. Also if I keep the rpm's up closer to 800 while sitting at a stop the cel won't come on but if I let it idle normally eventually it throw the code

Hope that makes sense

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Mine doesn't throw a code but if I'm sitting at the light with the ac off my idle drops down close to 300 then jumps back to normal idle for the car it doesn't miss or stall it just takes a dive on the idle and I clean the maf sensor and throttle body pretty regularly while having the battery disconnected
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I checked the MAF and cleaned it as well and if it's running and I unplug it it will stall so I'm assuming it is working, I've read that the iacv may need clean and I feel like a dork but and unless I'm blind does an 07 2.5 have an iacv ? And if so where is it ? Also read it may be an injector

Like I stated before when it is cold it idles fine it's only when it's driven for a bit that the idle drops a low

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I would say to just give the car some more time to relearn its idle, and see if the problem goes away on its own after a week or two. If the problem persists after a week or two, then I would dig a little deeper.
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May be a can of fuel system cleaner. or two. Isn't it B11 or something like that, there was a thread here a year or so ago about cleaners.

 

I bought a can, but can't remember the name, if you walk into the auto parts store it there ont he shelve.

 

Seafoam gets good ratings too.

 

Why are you sitting and letting it idle ? Does the car ever get high rpm to clean things out ? does the car ever get highway miles ?

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

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When sitting at a red light I can watch the rpm's slowly drop from around 800 down to 550 or so

And yes I took it out yesterday and did around 50 miles of interstate driving and blew the dust out of it so to speak

And I have run 2 cans of seafoam through it so far

Strange thing is the miss doesn't happen all the time there are times when I'm sitting at a light and can let it idle and it's smooth as silk other times it just will shake until I give it a bit of gas then it clears up

It's def got me scratching my head

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I hear ya I blew mine out a good bit this past weekend down at h2oi and I do a good bit of highway to I always clean my butterfly valve and maf sensor every time I change oil and I do seafoam treatment every 3rd to 4th oil change but if I'm sitting at a red light mine will dip down to about 300-400 ROMs for a second then come right back up to normal I don't know if its all the time though just when ever I pay attention and watch my tach needle I see it
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What happens when sitting at idle and you turn the steering wheel ? Does the rpm's jump up/down ?

 

My wagon does that every now and then. My idle has been set at 850-900rpm by my tuner.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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Well did some digging here's what I have done

Changed the intake gasket, MAF sensor cleaned the egr valve, swapped out the injectors

And what did I get for all that NOTHING !!

Runs exactly the same fantastic driving around but go through a drive thru and it will idle fine for a bit then start running rough and throw the cyl 1 misfire and idle low but here's the thing it's not all the time kinda intermittent I let it sit out in my lot and idle for 20 mins and it was fine so I don't think it's a valve wouldn't that be all the time ???

Im leaning towards the front 02 sensor..... Maybe ??

Back to the drawing board

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I have almost the same problem, low idle and Cyl 1 misfire, but I think the problem have something to do with throttle, sometime the car is normal then I hit a road hole or speed reduction bumb or anything that shake the car the problem start low idle and Cyl 1 misfire on next stop, the problem keep until next day and sometimes it keept until goes worse and CEL up and the car become un drivable I have to stop and shutoff and start the engine 3 times and the car become normal again, this problem have show up like 6 time in 10 months but after last week I have this problem everyday first I thought was a tune problem because I tune the car two weeks ago, but after 3 days I see definitely is relate to the throttle problem. Hope this help, the car go to the mechanics on next week.
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Have you made sure the connector on the coil is clean and fully engaged.

 

One member found one of his...less then tight a few months back.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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