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01-18-2013, 09:22 PM | #1 |
Scooby Newbie
Member#: 344052
Join Date: Jan 2013
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No power under load. Bad gas?
Hey guys,
I have been stuck with this problem for over a month now. I have an 06 STi (pretty much bone stock). I installed a short ram intake 2 weeks before this happened. One day I randomly start the car and I have no power whatsoever and idle is a bit rough. When I press the throttle I can hear a "burping" or backfiring sort of sound from the intake. The engine has a strong hesitation and I have troubles reving it past 3000rpm. I have no CEL and nothing had come up in the past. I took off my entire intake system including the turbo inlet and all the hoses are fine. Inspected the inter cooler as well. I replaced the MAF with a known working one and no difference. I put the stock air box on and reset the ecu and still no luck. Any ideas?
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01-19-2013, 03:44 AM | #2 |
Scooby Specialist
Member#: 193940
Join Date: Nov 2008
Location: Philly
Vehicle:2004 WRX STI Black RalliSpec Shortblock |
With a short ram you would have needed a tune for that. If you have not tuned for the short ram, you might have blown a ringland, maybe. Take the oil fill cap off while the car is running and see if any exhaust gasses are comming out of there.
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01-19-2013, 08:29 AM | #3 |
Scooby Newbie
Member#: 263329
Join Date: Nov 2010
Chapter/Region:
MWSOC
Location: Columbus, OH
Vehicle:2011 Impreza WRX DGM |
Yeahhhh I hope you tuned it.
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01-19-2013, 11:00 AM | #4 |
Scooby Specialist
Member#: 151809
Join Date: Jun 2007
Chapter/Region:
South East
Location: New Orleans
Vehicle:2007 WRX Black |
Man that sucks... hate to tell u but its not bad gas.
Compression test asap and leak down test. Probl. A blown ringland like stated. Try not to drive it as that may cause more damage making the repair more $$$$ . |
01-19-2013, 07:46 PM | #5 |
Scooby Newbie
Member#: 344052
Join Date: Jan 2013
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I took off the oil cap and no smoke (at start and while reving). I looked at the exhaust gas and no sign of blue smoke either.
The car idles smoothly but then drops to like 100 rpm for about 5 sec and then rev's back up as if the ecu is compensating the fuel ratio. When the rpm's drop that low is only shaky then. Is it possible that it might be an o2 sensor? I cant see it being the rings if this problem happened overnight. Car ran strong the whole time. Im gonna run the compression test, and leak down test on monday and let you guys know whats up. |
01-19-2013, 08:00 PM | #6 |
Scooby Specialist
Member#: 151809
Join Date: Jun 2007
Chapter/Region:
South East
Location: New Orleans
Vehicle:2007 WRX Black |
Do a compression test and report back
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01-20-2013, 01:00 AM | #7 |
Scooby Specialist
Member#: 321842
Join Date: May 2012
Chapter/Region:
NESIC
Location: New Hampshire
Vehicle:08 460/420w 08 STi 17 Stock WRB WRX |
Also, are you tuned for that intake?
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01-20-2013, 11:17 AM | #8 |
Scooby Specialist
Member#: 245218
Join Date: Apr 2010
Chapter/Region:
South East
Location: FL
Vehicle:2013 STI Limited |
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01-20-2013, 12:05 PM | #9 |
Scooby Specialist
Member#: 151809
Join Date: Jun 2007
Chapter/Region:
South East
Location: New Orleans
Vehicle:2007 WRX Black |
Just do a compression test
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01-20-2013, 01:44 PM | #10 |
Scooby Specialist
Member#: 289688
Join Date: Jul 2011
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Dirty MAF.
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01-20-2013, 03:58 PM | #11 |
Scooby Newbie
Member#: 344052
Join Date: Jan 2013
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01-20-2013, 04:12 PM | #12 |
Scooby Newbie
Member#: 198278
Join Date: Dec 2008
Location: ohio
Vehicle:2006 sti 3 stage gold prl white |
the wires brake right by the battery for the engine harness
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01-22-2013, 12:19 AM | #13 |
Scooby Newbie
Member#: 344052
Join Date: Jan 2013
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I did a compression test today and all cylinders are almost spot on to 105psi (I did not warm engine prior to testing). Spark plugs looked fine as well as the coils.
Plugged a timing light in and the value at idle was 7 degrees and then jumped to 18 degrees when the engine started to bog down. Do you guys think it may be a failed crankshaft position sensor? |
01-22-2013, 12:32 AM | #14 |
Scooby Specialist
Member#: 321842
Join Date: May 2012
Chapter/Region:
NESIC
Location: New Hampshire
Vehicle:08 460/420w 08 STi 17 Stock WRB WRX |
I don't think your car would start if it's a failing crankshaft position sensor.. that and a CEL.
I wonder if it's a bad knock sensor? Do you have an access port and are able to log? Sounds like it might be pulling a ton of timing.. |
01-22-2013, 12:33 AM | #15 |
Scooby Specialist
Member#: 321842
Join Date: May 2012
Chapter/Region:
NESIC
Location: New Hampshire
Vehicle:08 460/420w 08 STi 17 Stock WRB WRX |
also, what about other throttle positions - like 1/4 or 1/2 throttle? any bogging?
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01-22-2013, 12:36 AM | #16 |
Scooby Specialist
Member#: 321842
Join Date: May 2012
Chapter/Region:
NESIC
Location: New Hampshire
Vehicle:08 460/420w 08 STi 17 Stock WRB WRX |
could also be fuel pressure.. either from pump or regulator. just throwing ideas out there at this point since you checked air, spark, and compression..
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01-22-2013, 01:32 AM | #17 |
Scooby Newbie
Member#: 241311
Join Date: Mar 2010
Chapter/Region:
South East
Location: GA ATL SON
Vehicle:95L V6WRXSTI type R HE?RP DERP |
ive had this problem before i had a dead coil check the packs
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01-22-2013, 08:52 AM | #18 |
Scooby Specialist
Member#: 330625
Join Date: Aug 2012
Chapter/Region:
NESIC
Location: MA
Vehicle:2006 WRX WRB |
The timing jumping up when the revs drop at idle is normal the car is trying to maintain the idle rpm. 105 compression is pretty low, but it was even so it could have just been the testing method (ie closed throttle plate instead of open) or the tester (really long hose, inaccurate gauge, etc). It might be an intermittent bad coil pack but this is so hard to diagnose without data from the ecu.
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02-02-2013, 10:08 PM | #19 |
Scooby Newbie
Member#: 344052
Join Date: Jan 2013
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Problem fixed! It was a stuck valve in cylinder #4. Had to replace the shims
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02-02-2013, 10:34 PM | #20 |
Scooby Specialist
Member#: 155178
Join Date: Jul 2007
Chapter/Region:
NWIC
Location: Tualatin OR
Vehicle:2004 435 WHP EVO 8 Nasty silver |
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02-25-2013, 09:36 AM | #21 |
Scooby Newbie
Member#: 279645
Join Date: Apr 2011
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Ecu logic dictates that if the cam signal is not seen on start up the car will not start the first crank but will ignore the bad cam sensor and start the second crank with a CEL for a cam sensor. (on sti's ur avcs will be deactivated also)
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