|
12-20-2010, 09:06 AM
|
#1
|
|
CSS regular
Join Date: Oct 2003
Location: Cinci-nasty
Age: 45
Posts: 762
|
consistent random misfire 2007 LGT 2.5 Turbo
Hey guys,
We picked up Allan's sweet old scooby and it has been great so far with one exception...
The car recently had the spark plugs replaced @ 93k miles, Denso Iridiums, and it is still throwing random misfire codes for multiple cylinders... 1-3 mostly if that matters
I have seen some folks online that have said it could be as easy as a vacuum leak or as bad as reflashing the ECM
Anybody have any experience with this issue?
Car runs well, issue is mostly at idle, still boosts 12lbs etc.
thanks in advance for any pointers
any good independent subaru mechanics?
__________________
Remi
92 VW Corrado SLC Dark Burgandy
K&N w/ modded airbox Custom 2.5" exhaust Bilstein Sport/H&R Sport (now in the garage) 
2004 VW GLI 1.8T Platinum Grey (200hp VW) 
2007 Subaru Legacy GT Limited Wagon (Wife's grocery getter)
|
|
|
|
Sponsored Links
|
|
Advertisement
|
|
|
12-20-2010, 09:14 AM
|
#2
|
|
Damn Krauts
Join Date: Oct 2003
Location: WestChester
Age: 44
Posts: 3,683
|
Quote:
Originally Posted by Remman4
Hey guys,
We picked up Allan's sweet old scooby and it has been great so far with one exception...
The car recently had the spark plugs replaced @ 93k miles, Denso Iridiums, and it is still throwing random misfire codes for multiple cylinders... 1-3 mostly if that matters
I have seen some folks online that have said it could be as easy as a vacuum leak or as bad as reflashing the ECM
Anybody have any experience with this issue?
Car runs well, issue is mostly at idle, still boosts 12lbs etc.
thanks in advance for any pointers
any good independent subaru mechanics?
|
I actually had the same issue last winter on my speed6. Whenever I would get into boost it would misfire and throw that code. I eventually figured it out. The Denso Iridiums I had in the car were toast. Seemed the maf got dirty, made the car run stupid rich, plugs toast. Check them again. And do a boost leak test.
__________________
Quote:
Originally Posted by cincySVT
We need to talk to push, but always down for hooters. Nobody can be mad with wings, beer, and titties in their face  |
|
|
|
|
|
12-20-2010, 09:19 AM
|
#3
|
|
4G63 > LSX
Join Date: Sep 2007
Location: West Chester, OH
Age: 42
Posts: 6,708
|
any mods done to the car?
|
|
|
|
|
12-20-2010, 10:50 AM
|
#4
|
|
Small Boost.
Join Date: Nov 2003
Location: Florence, KY
Age: 45
Posts: 7,269
|
^Good question. Take it to a dealer. Why keep throwing money at it. Also put in an oem replacement plug.
__________________
2006 Subaru Forester XT 5 Speed
2007 Subaru Forester STI 6 Speed
2008 Suzuki Blvd.
|
|
|
|
|
12-20-2010, 01:14 PM
|
#5
|
|
CSS regular
Join Date: Oct 2003
Location: Cinci-nasty
Age: 45
Posts: 762
|
The car has an SPT cat back exhaust, but is otherwise stock for engine mods
at one point it had an intake, but due to issues with the MAF that was returned to stock before we bought it
I thought the plugs were OE replacements, maybe they were NGK iridiums and not Denso; I will double check with the shop who did the work
It was rough at idle before the new plugs, they were replaced due to mileage on the old ones
|
|
|
|
|
12-20-2010, 01:40 PM
|
#6
|
|
4G63 > LSX
Join Date: Sep 2007
Location: West Chester, OH
Age: 42
Posts: 6,708
|
If it had an aftermarket intake, it most likely had one of those oily filters on it. First thing I would do is clean the MAF sensor and do a battery pull to reset the ECU.
Buy yourself a can of this stuff and go to work.
http://shop.advanceautoparts.com/web...7CGRP2030C____
where are you located at?
Last edited by SloRice; 12-20-2010 at 01:41 PM..
|
|
|
|
|
12-20-2010, 03:33 PM
|
#7
|
|
Damn Krauts
Join Date: Oct 2003
Location: WestChester
Age: 44
Posts: 3,683
|
Quote:
Originally Posted by Remman4
The car has an SPT cat back exhaust, but is otherwise stock for engine mods
at one point it had an intake, but due to issues with the MAF that was returned to stock before we bought it
I thought the plugs were OE replacements, maybe they were NGK iridiums and not Denso; I will double check with the shop who did the work
It was rough at idle before the new plugs, they were replaced due to mileage on the old ones
|
Im willing to put money on it that its either a) your maf or b) your plugs. Do what tuned said and reinstall the oem plugs. I went and bought the 2 dollar plugs for the speed6 and thats how I found out mine were toast. Then replaced with step 1 denso's. Good luck |
|
|
|
|
12-20-2010, 06:08 PM
|
#8
|
|
CSS regular
Join Date: Oct 2003
Location: Cinci-nasty
Age: 45
Posts: 762
|
It did at one point have the oiled filter, but it has been running a standard paper filter for a few thousand miles. I would have thought that the MAF would have cleaned up by now.
I do not have the old plugs, but may go out and get a new set of OE plugs for s & g
I am located near Kenwood mall
|
|
|
|
|
12-20-2010, 06:49 PM
|
#9
|
|
4G63 > LSX
Join Date: Sep 2007
Location: West Chester, OH
Age: 42
Posts: 6,708
|
The MAF doesn't clean itself. You have to do it.
Who did the plugs the first time?? What are they gapped to?
|
|
|
|
|
12-20-2010, 07:14 PM
|
#10
|
|
CSS Rep King
Join Date: Nov 2005
Location: Mason
Age: 36
Posts: 7,078
|
Put in OE plugs, correctly gapped, and clean the maf like everyone said. Start with the cheap easy stuff. I guarantee that'll fix it.
|
|
|
|
|
12-20-2010, 07:16 PM
|
#11
|
|
Damn Krauts
Join Date: Oct 2003
Location: WestChester
Age: 44
Posts: 3,683
|
What he, and everyone said. Get the electronics clener, cheap plugs and do work
|
|
|
|
|
12-21-2010, 11:30 AM
|
#12
|
|
Small Boost.
Join Date: Nov 2003
Location: Florence, KY
Age: 45
Posts: 7,269
|
When I sold my legacy to a guy from cleveland he called me a few weeks later saying it was misfiring.It was at the dealer the day he bought it as they were replacing the valve cover gasket. He ended up taking it in and they said that 1 of the coil packs was not plugged back in correctly. I would check that as well
Last edited by Tuned200; 12-21-2010 at 05:22 PM..
|
|
|
|
|
12-21-2010, 04:51 PM
|
#13
|
|
CSS regular
Join Date: Oct 2003
Location: Cinci-nasty
Age: 45
Posts: 762
|
thanks guys, I will keep you posted
|
|
|
|
|
12-22-2010, 10:13 AM
|
#14
|
|
Small Boost.
Join Date: Nov 2003
Location: Florence, KY
Age: 45
Posts: 7,269
|
Strange this comes up as my 2007 forester xt Turbo just threw a p0301 cylinder 1 misfire code.
|
|
|
|
|
12-22-2010, 06:05 PM
|
#15
|
|
I gots a Datsun
Join Date: Jun 2008
Location: Linwood
Age: 46
Posts: 2,002
|
Quote:
Originally Posted by Tuned200
Strange this comes up as my 2007 forester xt Turbo just threw a p0301 cylinder 1 misfire code.
|
What type of intake gaskets do these use? many cars with plastic/silicone type gaskets have issues when the weather turns this cold. I know the older subies had an aluminum intake and graphite gaskets but i haven't messed with anything newer....
Is the op's car a coil on plug type? Or does it use paired coils like the older ones?
__________________
 
|
|
|
|
|
12-23-2010, 08:13 AM
|
#16
|
|
CSS regular
Join Date: Oct 2003
Location: Cinci-nasty
Age: 45
Posts: 762
|
The dealer tech mentioned that these newer 2.5T engines are having intake manifold gasket issues and a leak down test was suggested
that will hopefully take place today and then I will share the results with the group
these cars have the coil pack directly booted on the plugs very much like a VW 1.8T
stay tuned...
|
|
|
|
|
12-24-2010, 11:27 AM
|
#17
|
|
Small Boost.
Join Date: Nov 2003
Location: Florence, KY
Age: 45
Posts: 7,269
|
Coil on plug type.
His car has a plastic intake manifold.
|
|
|
|
|
12-27-2010, 10:15 AM
|
#18
|
|
CSS regular
Join Date: Oct 2003
Location: Cinci-nasty
Age: 45
Posts: 762
|
well, the leak test shows the engine is nice and tight... that's the good news
the bad news is that the subaru master tech at Beechmont Subaru has been battling a similar issue on another 2.5T and can't isolate the problem...
now they will have two to play with to sort it all out
I will update this post as I hear more
|
|
|
|
|
12-27-2010, 10:18 AM
|
#19
|
|
Damn Krauts
Join Date: Oct 2003
Location: WestChester
Age: 44
Posts: 3,683
|
Have you cleaned the maf with electronics cleaner and changed the plugs to oem ones. Both very easy to do.
|
|
|
|
|
12-27-2010, 02:06 PM
|
#20
|
|
CSS regular
Join Date: Oct 2003
Location: Cinci-nasty
Age: 45
Posts: 762
|
Quote:
Originally Posted by cincySVT
Have you cleaned the maf with electronics cleaner and changed the plugs to oem ones. Both very easy to do.
|
the car is not in my hands at the moment |
|
|
|
| Thread Tools |
|
|
| Display Modes |
 Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -4. The time now is 03:51 PM.
|
|
Your Privacy Choices