Main IndexAuto Repair Home Search Posts SEARCH
POSTS
Who's Online WHO'S
ONLINE
Log in LOG
IN







Search Auto Parts

Mysterious starting issue on my Subaru


  Email This Post



impreza808
Novice

Feb 20, 2017, 2:33 PM

Post #1 of 13 (223 views)
Mysterious starting issue on my Subaru Sign In

I have a 2008 Subaru Impreza WRX STI.

I have this starting issue that been plaguing me for some time now. None of the local mechanics could not figure it out.

Basically, the car will take up to 5sec to start, when the engine is shut off, and wait about 15min, all the way to overnight. If I start the engine within a couple min, it will start quick(it does get longer as more time passes). If I try to start it immediately after shut down, it fires up like brand new.

However, if I let it sit for a longer time, say couple of days, it will fire up immediately. Also, leaving the cylinder open, like when I changed out the spark plugs, also allows for fast starts.

Two of the plugs looked black, but was also wet. Couldn't tell if it was oil or gas.

As for the fluids, coolant looks good and oil doesn't look milky.
I'd assume if there was a fluid leak into the cylinders, I would leave a trail of smoke, but none of that either. EXCEPT on those hard starts when the car has been parked for several hours. There would a initial puff of whitish smoke, and none thereafter.

From the information we have, what could be the possible culprit?
Thanks


(This post was edited by impreza808 on Feb 20, 2017, 2:42 PM)


kev2
Veteran
kev2 profile image

Feb 20, 2017, 3:07 PM

Post #2 of 13 (206 views)
Re: Mysterious starting issue on my Subaru Sign In

Confusing - hopefully just an oops.
" None of the local mechanics could not figure it out. "
So they all figured it out - just will not tell you?


Anyway -
Scan for codes even if light is out.
fuel pressure test then with KOEO observe fuel pressure drop ie drops Xpsi in 5min.
Any aftermarket BS or modifications ?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Feb 20, 2017, 11:57 PM

Post #3 of 13 (191 views)
Re: Mysterious starting issue on my Subaru Sign In

! Two cylinder's had fouled plugs and nobody has a clue? That's the trouble. Fuel, oil could foul them, coolant generally if slow cleans them. Any could appear as a smoke upon start up or continuously if bad enough while running the color says which fluid is burning. White - coolant, blueish is oil and black is usually unburned fuel,


T



impreza808
Novice

Feb 21, 2017, 10:54 AM

Post #4 of 13 (162 views)
Re: Mysterious starting issue on my Subaru Sign In


In Reply To
! Two cylinder's had fouled plugs and nobody has a clue? That's the trouble. Fuel, oil could foul them, coolant generally if slow cleans them. Any could appear as a smoke upon start up or continuously if bad enough while running the color says which fluid is burning. White - coolant, blueish is oil and black is usually unburned fuel,


T


yeah, weird eh? I had two shops look at them, and they just swapped the plugs and called it a day. Spent almost $500 just to get the plugs changed, and it didn't even fix the starting issue that I originally brought the car for. When I asked them that there must be an underlying issue causing this, and they said it is normal for a modded car to do this. Normal, meaning the plugs get fouled up to the point of failure within a couple months? I had this tune on the car for 6 years with no issues, please. It is a very mild one, just a downpipe and a tune to get a little more HP and smooth out the terrible factory one. I did swap out the plugs two years ago myself, and they looked fine at that time.

I did swap around the plugs, and the misfire followed the plug, so at least that was the cause for the P303 code. But I still need to find out why this is happening. This incident of the plugs being fouled up and the starting issue is probably related. The smoke that comes out is greyish, and smells like unburnt gasoline. The smell of the wet plugs that came out smells like gas too. But I thought unburnt gas comes out black?

I am scheduling a leak down test soon.


(This post was edited by impreza808 on Feb 21, 2017, 11:03 AM)


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Feb 21, 2017, 11:06 AM

Post #5 of 13 (150 views)
Re: Mysterious starting issue on my Subaru Sign In

Which two cylinders have wet plugs?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


impreza808
Novice

Feb 21, 2017, 11:27 AM

Post #6 of 13 (140 views)
Re: Mysterious starting issue on my Subaru Sign In


In Reply To
Which two cylinders have wet plugs?


It was cylinders 1 and 3. When I pulled out the plugs last night, the threads were wet with what I assume is gas. I'm going to replace the bad plug tonight, will post a pic of the old plug then.

I'll also try to post a vid on the startup smoke.
Thanks


(This post was edited by impreza808 on Feb 21, 2017, 11:28 AM)


kev2
Veteran
kev2 profile image

Feb 21, 2017, 11:33 AM

Post #7 of 13 (136 views)
Re: Mysterious starting issue on my Subaru Sign In

"normal for a modded car to do this."
A down pipe? a non factory tune - explaining this may help ?
Hopefully there is NO CAI or K&N type BS....it all matters.


impreza808
Novice

Feb 21, 2017, 11:45 AM

Post #8 of 13 (134 views)
Re: Mysterious starting issue on my Subaru Sign In


In Reply To
"normal for a modded car to do this."
A down pipe? a non factory tune - explaining this may help ?
Hopefully there is NO CAI or K&N type BS....it all matters.


Nope, stock air box.
1. Cobb Accessport stage 2 map
2. Invidia catted DP
3. Boost gauge
4. Perrin turboinlet (factory one ripped, cost too much to put in another one. Lots of people say those are garbage anyway)

All else stock.

I had the top three in the car since 2010, changed oil every 3-4k miles.


(This post was edited by impreza808 on Feb 21, 2017, 11:50 AM)


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Feb 21, 2017, 6:54 PM

Post #9 of 13 (108 views)
Re: Mysterious starting issue on my Subaru Sign In

Have you checked to make sure that the fuel pressure regulator isn't leaking into the intake manifold via the vacuum hose?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


impreza808
Novice

Feb 22, 2017, 11:27 AM

Post #10 of 13 (92 views)
Re: Mysterious starting issue on my Subaru Sign In

Tried that, left the vacuum hose out to see if any fuel starts spewing from it. Watched for about 5min, nothing came out. Is that long enough?

I am planning to do a fuel pressure test this weekend. Then get the leak down test next week.

Got an image of the failing plug last night.
The plug smelled pretty strong of gasoline, and the threads were wet from it.
http://imgur.com/3Db5UBl

I replaced it with an old one from a while back, and the misfire is gone now.
Still need to find out the root cause of the hard start and fouled up plugs.


(This post was edited by impreza808 on Feb 22, 2017, 11:37 AM)


impreza808
Novice

Feb 22, 2017, 11:35 AM

Post #11 of 13 (88 views)
Re: Mysterious starting issue on my Subaru Sign In

Just a thought, the O2 sensor is reading around 14.7 AFR which is ideal. But how can it read 14.7 when the car smells like it is running rich?


(This post was edited by impreza808 on Feb 22, 2017, 11:36 AM)


kev2
Veteran
kev2 profile image

Feb 22, 2017, 12:17 PM

Post #12 of 13 (77 views)
Re: Mysterious starting issue on my Subaru Sign In

your not understanding - the fuel pressure test key in run position - KOEO*- observe and record the pressure - the pump will turn off after @1 minute, then observe the pressure drop, drops Xpsi in 5min - I suspect you will see a problem here.
The KOEO position will check leaking or wiring issues with injectors. same test just 5 extra minutes...
What are the o2 sensor voltages?
What are fuel trims?
WHat is Ect ?


*KOEO Key On Eng Off


impreza808
Novice

Feb 27, 2017, 6:10 PM

Post #13 of 13 (41 views)
Re: Mysterious starting issue on my Subaru Sign In

So I did the fuel pressure test and got a leak down test done at the dealer.
For the fuel pressure, the system maintains the factory spec of 33-34psi at idle. When I turn the key off, and come back 15 min later, the pressure is 15-20psi. Did this five times, and the numbers are consistent. Overnight, the pressure eventually went to zero.

The leak down test came out negative, all cylinders maintained a similar pressure.

They saw the wet plugs, and suspected that the delayed hard start is due to the fuel slowly leaking into the cyclinders, creating a semi flooded condition. They suggested I do an injector clean at a specialty shop.

But do you guys think it is faster to just get a new set of injectors than trying to figure out which ones are acting up and cleaning it?






  Email This Post
 
 


Feed Button




Search for (options) Privacy Sitemap

shopify
site analytics