Welcome to the North American Subaru Impreza Owners Club Sunday April 18, 2021
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Normally Aspirated Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 01-28-2021, 08:36 AM   #1
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default 06 Forester. very rough idle, stalls.

Suddenly, this 2006 Forester 5 speed non turbo, has started idling VERY rough and stalling. Seems to be rocking side to side too, as if the engine mounts were bad. Temperature is below freezing.

Could be EGR, Idle air control? No hoses, etc appear to be off, or loose. Spraying some starter fluid in the area of the intake to head area did not seem to change. I did pull the connector to the EGR, seemed to make no difference. Sharply tapping on it what hammer handle "may" have made some difference.

Only codes are recurring P0420 and a new P0852, which, to me, are not relevant.
* Registered users of the site do not see these ads.
joea99 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 01-28-2021, 11:41 AM   #2
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

This morning I re seated various under hood connectors, pressed on all the spark plug wires at plug and coil pack ends and connections.

While it cranked longer than expected (maybe 20 seconds), it started and idled smoothly at about 1500 RPM for a while, till I shut it off. Will drive it later to warm it up and see if it idles gets funky at normal temperature.

If it still idles OK, I guess there is nothing to do for now. But if it does not, it suggests some problem after warmup? Temp sensor, MAF, etc? Guess it could still be a vacuum leak too?
joea99 is offline   Reply With Quote
Old 01-28-2021, 03:52 PM   #3
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Quote:
Originally Posted by joea99 View Post
This morning I re seated various under hood connectors, pressed on all the spark plug wires at plug and coil pack ends and connections.

While it cranked longer than expected (maybe 20 seconds), it started and idled smoothly at about 1500 RPM for a while, till I shut it off. Will drive it later to warm it up and see if it idles gets funky at normal temperature.

If it still idles OK, I guess there is nothing to do for now. But if it does not, it suggests some problem after warmup? Temp sensor, MAF, etc? Guess it could still be a vacuum leak too?
After warmup it stalls at idle. Noticed it also "skips" when cranking, that ls crank speed races up, as if compression was down on a cylinder, spark plug loose, something like that. Fires up and wants to stall. Took it down the road and under light acceleration there is a "flutter" tapping noise that goes away when you back off and comes back when giving it gas.

It does not seem to be there at idle, but with the hood up and someone goosing the gas, I can occasionally hear something similar that appears to be coming from the driver side of the engine. Sounds almost like a loose valve, but it comes and goes as you vary the RPM.

Beginning to sound ominous.
joea99 is offline   Reply With Quote
Old 01-29-2021, 12:51 PM   #4
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Quote:
Originally Posted by joea99 View Post
After warmup it stalls at idle. Noticed it also "skips" when cranking, that ls crank speed races up, as if compression was down on a cylinder, spark plug loose, something like that. Fires up and wants to stall. Took it down the road and under light acceleration there is a "flutter" tapping noise that goes away when you back off and comes back when giving it gas.

It does not seem to be there at idle, but with the hood up and someone goosing the gas, I can occasionally hear something similar that appears to be coming from the driver side of the engine. Sounds almost like a loose valve, but it comes and goes as you vary the RPM.

Beginning to sound ominous.
Lots of views, not comments. So what might be a way to diagnose this? Local Subaru shop want $80 per hours "until found". Well, no thanks. Dealer want $115 flat fee. Still high, to me.

I might try the Subaru engine cleaner, then an oil and filter change as it might free up a sticky valve.

Will definitely try cleaning the throttle body as that seems to be a common idle problem, but seems unlikely, to me, to be only when the engine is hot. That is the part the really worries me. Almost has to be a mechanical issue give the associated "clatter" noise.
joea99 is offline   Reply With Quote
Old 02-02-2021, 08:45 AM   #5
Bluefoton
Scooby Guru
 
Member#: 141373
Join Date: Feb 2007
Chapter/Region: E. Canada
Location: Quebec, QC
Vehicle:
2019 Crosstrek Sport
6MT

Default

What's the mileage?
One issue that produces similar symptoms is simply a vacuum leak.
Bluefoton is offline   Reply With Quote
Old 02-02-2021, 09:12 AM   #6
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Quote:
Originally Posted by Bluefoton View Post
What's the mileage?
One issue that produces similar symptoms is simply a vacuum leak.
About 170,000 miles. I did think of a vacuum leak but a quick check did not find anything. I guess a more thorough check is in order. Once I can dig out of the snow.

Someone suggested the neutral switch code might do it, a bad switch affecting the ECU for idle and such. ?
joea99 is offline   Reply With Quote
Old 02-12-2021, 02:51 PM   #7
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Due to weather and having to work outside, no progress. Did order a MAF sensor, plugs and wires . . . just because.

But assuming something bad, like a loose valve seat, warped valve, funky rings, would it be better to:

Repair what may be known bad.
Total rebuild (myself)
Professional Reman
Salvage yard

Salvage seems very iffy as most I have browsed seem to be high mileage. And not all that cheap.

Rebuild myself is an option, but I have never done a Subaru and wonder at pitfalls. Is there a good source for specifics for this engine?
joea99 is offline   Reply With Quote
Old 02-13-2021, 02:15 PM   #8
serrilion
Scooby Newbie
 
Member#: 348982
Join Date: Mar 2013
Chapter/Region: NESIC
Location: Shoreham, VT
Vehicle:
2002 TS
Multi

Default

I would look into a vacum leak as a maybe corporate as a high idle is in play but I also wondered about a bad trottle body gasket allowing air into the intake mani.

A Simple test could be spray bottle with soap and water to see bubbling ect. I would deff change the MAF as that could be very dirty, the plugs and wires are always a good idea.

Your 1st code does effect all of this as its what your car uses to detect how its running. With out it, the ECU is guessing on air and fuel mixtures burning correctly, I would also look into that as well. Should be the 1st 02 sensor before your Cats.

The 2nd code has to deal with your transmission and would only effect your cars drivablilty with AWD shifting ect, deff something to look into as I believe they come into the car the same place, may have just come un plugged due to heavy ice snow?
serrilion is offline   Reply With Quote
Old 03-03-2021, 04:45 PM   #9
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Just did dead cold compression check. 1 hole was 180. the other three were 30-90.

Gee. I wonder what that could mean?
joea99 is offline   Reply With Quote
Old 03-04-2021, 01:27 PM   #10
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Funny thing. Just looked at the plugs and one had ZERO gap, like it had been mashed down. I gapped it an put it back in, just for a test. Started up OK and as it warmed up, got lumpy and wanted to die at idle.

Cooled down, pulled the plug to check and it looked fine. If it was installed that way by a heavy hand, it should have run bad all along, yes? So to me, only some mechanical problem related to piston motion could cause it while running. Yet, a boroscope shows no visible marks on the piston.

I can say the radiator hoses are quite hard when hot, but no coolant seems lost and oil seems normal color.

joe a.
joea99 is offline   Reply With Quote
Old 03-09-2021, 06:57 PM   #11
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

I started attacking this again, staring with cleaning the throttle body. I removed it and it took almost a full can of cleaner to do the deal.

While at it, I found the MT neutral switch is bad, flakey, so ordered one.

But, one concern about the PCV system reared it's ugly head again.

I revisited a temporary "fix" I had made, using ty wraps, to hold the "pcv hose assembly" {I guess?} into the air box/chamber as it would not stay in on its own. I tried to attach some pictures but got "internal server error".

One thing, if there is looseness in these connections, is that, effectively, a vacuum leak?

I noticed the there is an electrical connector involved. That suggests some kind of sensor, valve, actuator or thingambob exists. Yet, there appears to be nothing in either the white plastic part or the dohicky it plugs into. So, I wonder why there is an electrical connector there. Is something missing?

Since this seems to be part of the PCV system, I have to wonder what I am looking at and how it is supposed to work. No amount of skimming the FSM or the online OEM parts dealers seems to tell me what I need to know And some seem to lead me astray as the parts don't exactly match what I have.

Somebody know what this SHOULD look like, have part numbers, etc?
joea99 is offline   Reply With Quote
Old 03-13-2021, 05:23 PM   #12
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

After putting in the neutral switch, it seemed better and an initial test drive found the stalling between shifts was gone. But. I slowed to turn around and it stalled and gave me a hard time going back.

The rough idle returned. Short story, a compression test revealed 0ver 150 on the right (1,3) and 30 on the left (2,4).

I've parked it and pulled the plates for now. The only thing for this is an engine swap or a tear down. I guess first thing is to look at the timing belt to see if maybe it slipped time. If so, perhaps I have bent valves on that side?

With 170,000 miles what are the chances that the rings and pistons are OK and new valve guides/seals as required might reduce oil consumption? Is it possible to re-ring these engines without splitting the case?
joea99 is offline   Reply With Quote
Old 03-14-2021, 05:03 PM   #13
Vancouver98STi
Scooby Specialist
 
Member#: 459287
Join Date: Dec 2016
Chapter/Region: VIC
Location: Vancouver BC Canada
Vehicle:
1998 JDM Impreza STi
V4 GF8 White

Question

Quote:
Originally Posted by joea99 View Post

I tried to attach some pictures but got "internal server error".
And this was while using the NASIOC image host?

Quote:
Originally Posted by joea99 View Post

Short story, a compression test revealed 0ver 150 on the right (1,3) and 30 on the left (2,4).

With 170,000 miles what are the chances that the rings and pistons are OK and new valve guides/seals as required might reduce oil consumption?
Doing both a dry and a wet compression test would tell you more.
Vancouver98STi is offline   Reply With Quote
Old 03-14-2021, 06:38 PM   #14
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Quote:
Originally Posted by Vancouver98STi View Post
And this was while using the NASIOC image host?

Yes. Tried again just now after using a "reducer" to make the files smaller.

Doing both a dry and a wet compression test would tell you more.
I've heard of that, as I recall, it requires injecting some motor oil into the low cylinders? The idea being if the compression tests higher the rings are bad, if not, probably the valves?
joea99 is offline   Reply With Quote
Old 03-20-2021, 02:38 PM   #15
Elbert Bass
Scooby Specialist
 
Member#: 283429
Join Date: May 2011
Chapter/Region: South East
Location: Down yonder.
Vehicle:
2016 Fuji Sunfire 03
Silver

Default

Quote:
Originally Posted by joea99 View Post
--snip---
Short story, a compression test revealed 0ver 150 on the right (1,3) and 30 on the left (2,4).--snip----
Have you checked mechanical timing? one cause for that could be your left bank (2,4) cam is out of time. Especially since it affects both cylinders on one side.
Elbert Bass is offline   Reply With Quote
Old 03-20-2021, 04:18 PM   #16
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Quote:
Originally Posted by Elbert Bass View Post
Have you checked mechanical timing? one cause for that could be your left bank (2,4) cam is out of time. Especially since it affects both cylinders on one side.
I have not. I was going to do that after the wet compression test, but now may do it first. Got bitter cold again and waiting for a few warm days in a row.

Some things I read say if it did slip time most likely the valves are bent. What do you think? Only one way to know, of course, that is set the timing and retest. If it checks out good, then immediately replace the belt and associated hard parts. Actually, I guess I can just pull the belt and move the cam to where the valves should be shut and do a cylinder leak down test. That should tell me something.
joea99 is offline   Reply With Quote
Old 03-20-2021, 08:51 PM   #17
Elbert Bass
Scooby Specialist
 
Member#: 283429
Join Date: May 2011
Chapter/Region: South East
Location: Down yonder.
Vehicle:
2016 Fuji Sunfire 03
Silver

Default

Quote:
Originally Posted by joea99 View Post
I have not. I was going to do that after the wet compression test, but now may do it first. Got bitter cold again and waiting for a few warm days in a row.

Some things I read say if it did slip time most likely the valves are bent. What do you think? Only one way to know, of course, that is set the timing and retest. If it checks out good, then immediately replace the belt and associated hard parts. Actually, I guess I can just pull the belt and move the cam to where the valves should be shut and do a cylinder leak down test. That should tell me something.
Depends on how bad it is out of time. You can jump a tooth or two and not bend valves. Only way to know is check it, and if it is out of time retime and either perform another compression test or see if it runs better.
Elbert Bass is offline   Reply With Quote
Old 03-20-2021, 10:42 PM   #18
serrilion
Scooby Newbie
 
Member#: 348982
Join Date: Mar 2013
Chapter/Region: NESIC
Location: Shoreham, VT
Vehicle:
2002 TS
Multi

Default

When you said a spark plug was flattened that tells me the piston hit it, but it shouldn't have.

Low compression could be bad head gaskets. There are signs of this you can see, look up next to exhaust manifolds for drips between heads and block and back of the heads. Also check the coolant over flow tank for material in it. Also does the car still have good heat? wondering if a bad thermo is causing the car to run oddly

I personally would check the timing. Even if slightly off, re time it as its a strait forward process but can be a PITA sometimes while in the car.

As said before some oil in the cyl will tell you if the rings are bad, but at 170k I would susspect the valves have had some carbon build up, particularly on the intake valves as they never get quite hot enough to burn off, the exhaust valves due, but can be to hot and burn the carbon right onto them.

Also have you checked the intake manifold gaskets? both on the block and the throttle body gasket? might be getting to much air or air its not accounting for when its cold
serrilion is offline   Reply With Quote
Old 03-21-2021, 12:24 AM   #19
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Quote:
Originally Posted by serrilion View Post
When you said a spark plug was flattened that tells me the piston hit it, but it shouldn't have.

Low compression could be bad head gaskets. There are signs of this you can see, look up next to exhaust manifolds for drips between heads and block and back of the heads. Also check the coolant over flow tank for material in it. Also does the car still have good heat? wondering if a bad thermo is causing the car to run oddly

I personally would check the timing. Even if slightly off, re time it as its a strait forward process but can be a PITA sometimes while in the car.

As said before some oil in the cyl will tell you if the rings are bad, but at 170k I would susspect the valves have had some carbon build up, particularly on the intake valves as they never get quite hot enough to burn off, the exhaust valves due, but can be to hot and burn the carbon right onto them.

Also have you checked the intake manifold gaskets? both on the block and the throttle body gasket? might be getting to much air or air its not accounting for when its cold
I did put a cheap boroscope down the hole of the no gap plug and did not see any obvious sign of contact. After a regap and running it did not happen again. I took a chance with new plugs and there was no contact there either. Could have been just someone careless before I got it. But it did not seem to run too badly and would rev up just fine.

There are some oily spots but none seem to be at the head/block boundary.

I had been running OK and suddenly started bad idle and stalling. Some of that was due to the bad neutral switch, some may have been the really dirty throttle body, which has a new gasket now.

Tomorrow promises a warm afternoon, I can check it out better then.
joea99 is offline   Reply With Quote
Old 03-21-2021, 07:21 PM   #20
Elbert Bass
Scooby Specialist
 
Member#: 283429
Join Date: May 2011
Chapter/Region: South East
Location: Down yonder.
Vehicle:
2016 Fuji Sunfire 03
Silver

Default

Quote:
Originally Posted by joea99 View Post
I did put a cheap boroscope down the hole of the no gap plug and did not see any obvious sign of contact. After a regap and running it did not happen again. I took a chance with new plugs and there was no contact there either. Could have been just someone careless before I got it. But it did not seem to run too badly and would rev up just fine.

There are some oily spots but none seem to be at the head/block boundary.

I had been running OK and suddenly started bad idle and stalling. Some of that was due to the bad neutral switch, some may have been the really dirty throttle body, which has a new gasket now.

Tomorrow promises a warm afternoon, I can check it out better then.
I know of and have only seen two ways a piston can hit a plug in that engine. The wrong plug that was too long or the piston has broken. Broken piston would make a horrible racket and you would have a persistent "misfire". Someone probably jammed it down the spark plug tube trying to install it.

Oily spots on the bottom of the head at the head gasket only indicate oil leaking from the oil return galleys, NOT internal gasket issues. If your loss of compression was from a head gasket issue (with no combustion gas in cooling system or coolant in oil) it would be blown between the two cylinders - only way to diagnose that would be a cylinder leakage test.
Check that mechanical timing first, if that's OK check valve lash or if you have a cylinder leakage guage run that test first.
Elbert Bass is offline   Reply With Quote
Old 03-21-2021, 11:22 PM   #21
pigboat_2
Scooby Specialist
 
Member#: 247823
Join Date: May 2010
Chapter/Region: BAIC
Location: Denver/ Eglin AFB
Vehicle:
2006 Fxt
RBP

Default

Nobody has suggested a leak down test?
pigboat_2 is online now   Reply With Quote
Old 03-22-2021, 03:12 PM   #22
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Looks like timing is OK. I find the various write ups a bit vague. Being unfamiliar with boxster style engines I am not sure I'm using the correct marks, but, with the crank addrow almost straight up, the cam pulleys are straight up and look to be in the same position.

I do not see a reference mark on the right side (left side with face to car) but do see one on the right. Unless the left one is the edge where the casting changes a bit.

Also, the crank mark does not seem to be exactly straight up, but is offset a bit to the right (clockwise). Is that correct?

That aside for the moment, I guess a leak down check is next.
joea99 is offline   Reply With Quote
Old 03-22-2021, 06:09 PM   #23
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

Is there a write up on how to do a proper leak down test?

I dusted off my never used HF leak down tester and got results that confused me completely.

Apparently I do not know how to determine TDC properly on Subaru engines.

Is it sufficient to stick a feeler down the hole, rotate the engine till it "feels right" and trust that? And do the for each cylinder individually?
joea99 is offline   Reply With Quote
Old 03-23-2021, 01:17 PM   #24
joea99
Scooby Newbie
 
Member#: 483823
Join Date: Mar 2018
Location: Stone Ridge, NY 12484
Default

So, putting 1,3 at TDC and checking 1,3 I get "normal" (20%) leakage. No odd noises.

Putting 2,4 at TDC 4 shows "moderate" leakage and hisses pretty good, coming out plug hole of #2. I can almost stop it by sealing it with a finger.

At first I though "blown gasket", "cracked head". but. . . testing 2 on the other hand, seems normal, with no hissing sounds anywhere.

Tried #4 again with same results. Not sure what to think.
joea99 is offline   Reply With Quote
Old 03-23-2021, 01:59 PM   #25
Vancouver98STi
Scooby Specialist
 
Member#: 459287
Join Date: Dec 2016
Chapter/Region: VIC
Location: Vancouver BC Canada
Vehicle:
1998 JDM Impreza STi
V4 GF8 White

Question

Quote:
Originally Posted by joea99 View Post

Funny thing. Just looked at the plugs and one had ZERO gap, like it had been mashed down.
That cylinder wouldn't have been firing then.

Do you recall which cylinder that spark plug was from? Just wondering if there's a correlation between that particular plug and either one of the two low compression cylinders.
Vancouver98STi is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 01:34 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2021 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.