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Old 04-12-2021, 11:19 AM   #1
snow_bound26
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Default Stumbling issue v7 207

Apologize for length. Just trying to be thorough. Need some help. Tried posting this in the 207 info thread as well. No response.

Started off having an issue with high rpm hesitation/stumbling about 6-7 weeks ago. Basically engine did not want to rev past 7200. After getting some initial feedback of "it's your ignition coils", I went and replaced them with new ones. Previous ones had about 20k miles on them and were OEM. Put in new ones and new crank position sensor last week. Problem still there.

This morning I go to start the car and it didn't want to to fire up. Sputtered for a few seconds then reluctantly started to run. Let it idle for about 10 min which got smoother as it warmed up as I was listening from inside the house. Went to get in the car and could smell a little gas. Have had an issue with one of my clamps on the feed line coming loose so grabbed my screw driver to tighten it. Tight. Hadn't loosened up at all. Get in the car and give it a little gas to bring it up to 1500 and it sounds rough. Let foot off throttle and it wanted to stall. Gave it a few seconds and tried again and this time was fine. Decided to take it down the road a little and see what happens. Sounds rough, not the usual smooth I'm use to with this engine.

What should I be looking for? FPR? Cam position sensor? Wiring?

The following were done last fall when I finished up installing the 207:
New NGK BKR7EIX gapped to .028"
New walbro 255
New ID 1050x injectors
Older version Perrin fuel rails w/new fuel lines
2 new injector plugs on wiring harness
73mm KS intake
New silicone vac lines
Cleaned MAF sensor - about 20k on it
Tuned on 91oct - goes a tad rich at 7000, not sure why
New OEM flywheel
AVCS was working properly at time of tune

Replaced last week:
CPS part #22053AA053
Ignition coils part #22433AA561

Checked plugs while I was in there. Plugs were clean and didn't show any signs of burning rich/lean. Gaps still at .028".

Have since found conflicting info on what plugs I should be using. Tuner had me use heat range 7. Engine had heat range 8 when I purchased it. Info that I've found on the forum has stated both heat range 6 and 7 from the factory. Am wondering if this could be causing part of my high rpm issue (the rich condition at 7000)? Am thinking FPR could be the main source of high rpm stumbling and now the over all rough idle/driving that I felt this morning.

Letting the car cool down and going to check all my vac lines. Did recently install GrimmSpeed AOS, but that was about a month ago and the high rpm issue was present before that and didn't have any changes in start up or idle after install.
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Old 04-12-2021, 03:18 PM   #2
86Dreams
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Sorry to hear about that.
Id start by checking fuel trims to rule out any kind of vacuum/boost issues.
check the grounds around your motor and make sure theyre tight and clean.
compression test
check idle fuel pressure.
you could also try replacing the in line fuel filter in the engine bay altho idk if it can cause issues this bad.
you could also try some octane booster
and make sure your waste gate still moves freely

thats all the easy stuff I can think to start with.

after that
leak down check
make sure timing didn't jump

good luck and definitely post updates / solutions

anecdotally when my 205 blew my mechanic had some less than good opinions on the GS AOS, that said I blew mine by running like 8* too much timing at 20psi boost, so who knows.
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Old 04-12-2021, 03:30 PM   #3
K3rm1tth3fr0g
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Quote:
Originally Posted by 86Dreams View Post
Sorry to hear about that.
Id start by checking fuel trims to rule out any kind of vacuum/boost issues.
check the grounds around your motor and make sure theyre tight and clean.
compression test
check idle fuel pressure.
you could also try replacing the in line fuel filter in the engine bay altho idk if it can cause issues this bad.
you could also try some octane booster
and make sure your waste gate still moves freely

thats all the easy stuff I can think to start with.

after that
leak down check
make sure timing didn't jump

good luck and definitely post updates / solutions

anecdotally when my 205 blew my mechanic had some less than good opinions on the GS AOS, that said I blew mine by running like 8* too much timing at 20psi boost, so who knows.



FWIW my tuner said the GS AOS is only really a problem because it has a tendency to shred the main O-ring, and the IAG version is better in almost every way including being coolant heated to evap water and sludge. This is coming from someone currently running the GS unit. So far no issues but for what it is I can't really complain too much. It keeps my intake less oily.


And OP maybe consider posting a log.
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Old 04-12-2021, 04:07 PM   #4
TwistedAxles101
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Post some logs up. One while idling (warm) and another doing a WOT pull. Do you have a wideband?

As for the spark plugs, 7 heat range is factory for v7,8,9. Heat range 8 would be 1 step colder.

The grimspeed AOS is a half assed unit. It will keep oil out of your intercooler but not out of your intake manifold. I used to run one.

I'd probably start by:
Compression + leakdown tests
Check fuel pressure
Boost leak test
Vacuum leak test
Inspection of coil pack connecters, etc.

Last edited by TwistedAxles101; 04-12-2021 at 04:15 PM.
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Old 04-12-2021, 06:40 PM   #5
snow_bound26
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Only using the GS AOS because I got it for $50. A friend who got out of the Subaru game a while ago found it when he was cleaning out his garage. I eventually plan on getting the Killer B AOS. But I'm going to wait and see how much blow by I get at track events since I haven't had this project on the track yet.

Did a compression/leak down test before getting tuned last Nov. can't remember the numbers off the top of my head but they said engine was quite healthy. I had checked all connectors when I put the bulkhead harness in last fall. I will check those connectors again though.

Checked all vac lines, MAF, intake joints, wastegate actuator, EBCS, and fuel line clamps today and everything looks good. Still trying to figure out how to log with RomRaider. I'm missing something setting it up. I can see all the live data just fine, but when I try to log it doesn't give me anything to save. However, during the pull it appears that I'm reaching target boost, AVCS is functioning properly, no sign of knock or FLKC. Have no idea what I should be looking for with mass air flow. Once I figure out how to use the damn software correctly I'll post some logs. IAM is 16.

I did put some heet in the tank when I filled up today. Wondering if maybe there's some water in the tank or maybe a bad batch of gas at my usual station. Also ordered an OEM FPR just to be on the safe side. I'll talk with my tuner and find out why he wanted me to use OEM heat range plugs.

05 had fuel filter in tank which the sock filter was replaced when I did the fuel pump last fall. Grounds (battery, both heads, starter) were all made fresh last fall by me. No signs of corrosion and they are all still tight. Battery is an Odyssey PC925 that's 2 years old. Not sure about the age of the alt or the make. I can't read the plaque on it to know if it's OEM or not. I haven't seen any signs of a faulty alt, but I am beginning to question it.

What should I be looking for with fuel trims? Anything related to tuning is an area I haven't ventured into yet so other than making sure I'm reaching target boost, AVCS function, IAM, and reading knock values, I have no idea what anything actually means.
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Old 04-12-2021, 07:09 PM   #6
murrdogg24
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I would log injector duty cycle. Check everywhere for leaks...

Last edited by murrdogg24; 04-12-2021 at 07:14 PM.
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Old 04-13-2021, 12:07 PM   #7
86Dreams
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Quote:
Originally Posted by snow_bound26 View Post

What should I be looking for with fuel trims?
theres 4 different ranges for air flow, they correspond to different levels of manifold pressure and if one is higher or lower than the others it can point to where to look for some kind of leak. assuming your tuner didnt change the ranges they capture. if the D range is not adjusted that actually might be why you run a little rich at full boost, maybe.

do you have any pending misfire codes?

compression and leak down are still worth doing since the motor has been in service since the original test. compression is atleast pretty easy to do on your own, leak down needs special equipment.
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Old 04-13-2021, 04:39 PM   #8
snow_bound26
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Quote:
Originally Posted by 86Dreams View Post
theres 4 different ranges for air flow, they correspond to different levels of manifold pressure and if one is higher or lower than the others it can point to where to look for some kind of leak. assuming your tuner didnt change the ranges they capture. if the D range is not adjusted that actually might be why you run a little rich at full boost, maybe.



do you have any pending misfire codes?



compression and leak down are still worth doing since the motor has been in service since the original test. compression is atleast pretty easy to do on your own, leak down needs special equipment.

Thanks for the clarification on the fuel trims. I'll take a look when I get a chance.

I don't have any pending codes for anything.

I have everything to do compression and leak down, just need to find the time. I had the shop do it last Nov because it was in there for a couple things before being tuned so just wanted to see if everything was good or not.
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Old 05-03-2021, 03:47 PM   #9
snow_bound26
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Ended up replacing the OEM FPR, ran a tank with heet, and cleaned my grounds one last time even though they were pretty clean already. Haven't had any high RPM issues since.

Something else that has been brought to my attention is my alt not providing enough amps for everything I have done. I do notice RPM changes when I turn the stereo on or the fans kick on at a light. Are there any OEM alts that provide 120ish amps that will work with my 05?I believe it came with a 75a alt. Other option I'm considering is a DC Power 180a alt. Any other options I should consider?
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Old 05-03-2021, 04:08 PM   #10
GK1707
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OEM forester alternator is what you want, im running one in my 04. I believe it's either 90 or 110amps. Can't remeber off the top off my head but it's more than the oem wrx/sti alternator amps.
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Old 05-03-2021, 04:57 PM   #11
snow_bound26
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Quote:
Originally Posted by GK1707 View Post
OEM forester alternator is what you want, im running one in my 04. I believe it's either 90 or 110amps. Can't remeber off the top off my head but it's more than the oem wrx/sti alternator amps.


What year? I know early foresters were 75a like mine. I'd like something at least 110a so I have a little head room in case I decide to change anything else that could effect current draw.
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Old 05-03-2021, 10:50 PM   #12
GK1707
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Quote:
Originally Posted by snow_bound26 View Post
What year? I know early foresters were 75a like mine. I'd like something at least 110a so I have a little head room in case I decide to change anything else that could effect current draw.
Take a look at the 08 forester. Should be 110 amp and direct drop in
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Old 05-04-2021, 05:59 AM   #13
snow_bound26
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Quote:
Originally Posted by GK1707 View Post
Take a look at the 08 forester. Should be 110 amp and direct drop in


Will do. Thanks.
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