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Hi everyone,
I have had CEL lighting up only at 4000 rpms in parking or in any gear. Idling is fine. Codes are P0303 & P0304
Replaced spark plugs, coils and wires, tested compression (150 psi on all cylinders), tested oxygen and knock sensors.
Fuel trims seem to be normal, ST 0% and LT from -1 to -4 %
Mechanics I've been to fail to find the problem because they don't have any advanced diagnostic tools like oscilloscopes and dealership asks for too much money to find the problem.
Maybe someone can recommend a service shop that can diagnose the problem for fair price.
I'm located in Los Angeles, California.
2009 Subaru Legacy 2.5L non-turbo 120,000 miles
Thanks!
Not done. But shop made injector pulse test with Snap on tool I think. They said that injectors are good but they didn't take them off so it might be not completely reliable info.
My other thoughts based on info I found on the web were misadjusted valves or faulty torque converter.
Thank you for trying to help!
Interesting. :huh: Makes me wonder if the PCM is falsely flagging misfires because of a software error. The freeze frame fuel trims back this up to a degree, since they show no excessive correction. I've seen this on GM and Chrysler vehicles in the past.
Wondering if a good ol' battery disconnect would be a good idea. :blink: Assuming that the PCM has incorrectly learned a misfire profile, and would benefit from relearning.
Does this vehicle have VVT? I have seen low or poor oil condition cause misfire at higher rpm on some Subaru's . Also, has the engine ever been swapped?
"Silver bullets are for killing Werewolves, not fixing Cars." -Rob Longoria-
Yes the vehicle has VVT.
Funny you asked, the engine was swapped from Outback with 100,000 miles on it, but it's the same engine.
Had to replace old engine because I destroyed it, I went 110 mph on the freeway and i think i red zoned it (instant performance loss and loud knocking sounds). It also had about 100,000 miles.
I changed oil many times, (every 3,500 miles) getting oil level checked every 1,000 miles. I have to add a quart of oil every 1 thousand miles, but recently I think engine started consuming less oil (1 quart on 2 thousand miles). One explanation would be that the engine was not running for a while until I installed it and piston rings got back to their working shape. I put about 20,000 miles on new engine.
Thanks!
The reason why I asked about the engine swap was that I was thinking it might have the wrong cam or crank reluctor and confusing the PCM, but you mentioned you have had this engine in for 20k. So I think that can be eliminated. I would check the main engine harness connection for any signs of corrosion or fluids. Also make sure all your engine grounds are clean and tight. Next you might want to try to run some oil cleaner though your engine and some fresh oil and a good quality oil filter.
"Silver bullets are for killing Werewolves, not fixing Cars." -Rob Longoria-
Firing order is 1-3-2-4 so 3 & 4 are 360 crank degrees apart but on different banks.
That combination tends to make me thing crank sensor related issue, istr it is a 2 wire inductive sensor it might be worth checking it out and the associated wiring.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Last edit: 8 years 5 months ago by Andy.MacFadyen.
@Andy.MacFadyen,
thanks for response,
i will try to check this sensor and its wiring, but unfortunately i do not have an oscilloscope
and every car service shop i've tried to contact doesn't have it, they just want to replace parts hoping it will solve the problem but are unable to locate and diagnose the actual problem
Andy.MacFadyen wrote: Firing order is 1-3-2-4 so 3 & 4 are 360 crank degrees apart but on different banks.
That combination tends to make me thing crank sensor related issue, istr it is a 2 wire inductive sensor it might be worth checking it out and the associated wiring.
Good point, wish ts had oscilloscope. Also unbalanced flywheel is believed to cause "missfire"
Is this a manual transmission car ? Is the flywheel the one that came with the engine? Is it a Dual Mass Flywheel ? DMF can throw out a lot of metallic debris when they start to fail.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Andy.MacFadyen wrote: Is this a manual transmission car ? Is the flywheel the one that came with the engine? Is it a Dual Mass Flywheel ? DMF can throw out a lot of metallic debris when they start to fail.
It's an automatic transmission. Flywheel wasn't changed. I'm not sure if its a dual mass, googling my cars flywheel didn't show me that.
Andy.MacFadyen wrote: Is this a manual transmission car ? Is the flywheel the one that came with the engine? Is it a Dual Mass Flywheel ? DMF can throw out a lot of metallic debris when they start to fail.
It's an automatic transmission. Flywheel wasn't changed. I'm not sure if its a dual mass, googling my cars flywheel didn't show me that.
An automatic won't have a DMF the mass of fluid spinning round in the torque converter has a similar vibration damping effect.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
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