04 Outback H6 3.0 P0519 P0507 high idle and surging

[Ken2004LLBean]

Some background: Wife's car is a 2004 Outback LL Bean with H6-3.0, automatic, 153K.  A sudden, massive coolant loss destroyed the original engine.  Since a mechanic installed a used, replacement engine (with 100K) three months ago, the check engine light has remained on, with persistent codes P0519 and P0507, no matter what I've tried (see list below).  Idle speed also high (1,000 rpm in park, 850 rpm in drive), and idle speed also sometimes surges/hunts, both in park and drive, which causes car to buck.  Idle speed in park has sometimes gone as high as 1,300 to 1,500 in park, when engine is hot.  Also, car does not always start on the first crank, but will always start on second crank.  Surging rpm and hard starting have happened both with cold or hot engine.

Anyway, I downloaded the factory service manual and followed procedures for checking codes P0519 and P0507.  The most likely suspect for high/surging idle is vacuum leak, but neither I nor the mechanic have been able to find a vacuum leak (I used the carb cleaner spray method, he used a smoke test).

Steps I have taken so far, with no change in solving the problem:

- Replaced following parts with Subaru OEM parts: throttle position sensor, idle air control valve, PCV valve (old was was gunked) and PVC and air box breather hoses.

- Removed EGR valve to check valve and passageway on intake manifold for carbon buildup/blockage, but found no blockage.

- Adjusted throttle and cruise control cables.

- Replace throttle body gasket and cleaned throttle body.  Replace air filter (old one dirty).

- Replaced ECM with unit from salvage yard.

- Cleaned all ground connections I could find, and checked for loose electrical connectors.

- Tested for voltage and ground at various sensors (MAP, TPS and IAT)

The past few days, I have monitored live data from my basic scanner/code reader while driving, and I noticed one pattern: whenever I let off the throttle (whether from cruising speed, or acceleration), the car goes into open loop briefly and bucks, then returns to closed loop.  Also, when I experience surges in rpm, the ECM is in open loop.  Another pattern I've noticed is if I put the car in park, and press the throttle, I will get the surging rpm problem between 1,000-1,100, and also around 1,700-1,800 (very specific, reproduce-able ranges).  I don't know if the open loop is causing these surges, or is the effect of these surges.  The P0519 and P0507 codes; going into open loop going on and off the throttle; and surging rpm come back after resetting the computer by disconnecting the battery.

Since I get the surging when rolling on or off the the throttle, I used a DVOM and backprobed the TPS connector.  I get 0.7 volts at full closed throttle, and 4.5 volts at full open throttle, with smooth increase in voltage as throttle is opened.  I don't know if it's the throttle position, or a certain rpm range, as described above, that's sending the car into these open loop spasms.

Took the car back to the mechanic today to see if his expensive Snap-On scanner could reveal any smoking guns than my $40 scanner could not, but he said nothing jumped out at him, and that the fuel trims looked good to him.

The car cruises and accelerates smoothly and powerfully.  It only acts up when first letting on and off the throttle, in addition to sometimes hard starting and the always-high idle.

One other thing maybe worth mentioning:  my scanner shows emission monitor readiness status, and in the past several weeks of tinkering around with the car, the monitor for EGR has never entered ready status.  My mechanic thinks it may be worth replacing the EGR valve, although I hate to keep throwing parts at the car at about $100 a pop, even though my labor is free.  I've spent hours searching online and under the hood, and am growing beyond frustrated.  This car is consuming me.

-Ken

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[1 Lucky Texan]

Does the FSM mention an idle zero re-learn procedure?

also, check here;

 

Edited April 5, 2019 by 1 Lucky Texan

[Ken2004LLBean]

Hi, thanks for your response.

I have not come across an idle re-learn procedure in the FSM, but then again, I have only read a few parts of the manual, mainly DTC troubleshooting procedures relating to the codes I've had, and wiring/sensor/harness diagrams.

As for the link you provided, that's some interesting information, although it looks like the IACV on the H6 engine uses a different mechanism (a rotating, slotted cylinder, as opposed to a pintle at the end of a threaded shaft).  Before I installed a new, OEM idle air control valve, I tried cleaning the old one with throttle body cleaner after removing it from the TB (actually, I have two old IACVs - the one that was on the engine, and one I got from a junkyard - I cleaned both, and now I can't remember which one I reinstalled before installing a brand-new part).  Either way, cleaning an older IACV or installing a new one, seemed to make no difference.

I have not really done much electrical testing at the IACV harness, though, so that may be one of my next steps.  I also need to find out what's causing the car to jump in and out of open loop.

 

[Ken2004LLBean]

Well, per advice from another Subie forum, I cleaned all electrical connectors that would have been disconnected during the engine swap (also reset the ECM via battery disconnect).  This made a definite improvement in lowering my idle speed by an average of 50 to 100 rpm. Car now idles no higher than 1,000 in park (with higher engine temps), and as low as 850 in park (slightly lower engine temps).  Idle speed in drive in drive is between 700 and 800 (lower engine temps = lower idle speeds. Still had that annoying buck after going back and forth into open loop when letting off the throttle.

Check engine light stayed off for a day, but it came back the day after, with my old friends, codes P0519 and P0507, after putting it in park and it started to hunt/surge.

My next step may be replacing both front, and rear, O2 sensors (with Denso ones, of course).

 

Edited April 7, 2019 by Ken2004LLBean
to correct typo

[FerGloyale]

Did the mechanic retain the original Intake manifold?  Or did he just drop an entire replacement in with a J-yard intake?  Possible year model wiring difference if so?

Also, This model is notorious for the fuel pump unit's "surge" compartment's metal cap and o-ring leaking, causing low fuel pressure/volume and causing hard starts, and weird running performance.

Check the fuel pressure with a gauge.  Watch for bleed down at shut off.  Pull the pump unit from tank by lifting rear seat and pulling up the rubber mat and opening the access panel underneath. 

[Ken2004LLBean]

The intake is the one that came with the salvage yard engine, although my mechanic said he kept the engine wiring harness from the old engine b/c it was in better condition.

I was thinking that the dreaded fuel pump cap/O-ring issue might be starting to rear its ugly head.  The car starts fine most of the time, but maybe 1 out of every 5 starts or so, I will have to crank it twice to start it; this could happen when engine is cold or hot.  I will have to purchase a replacement cap and O-ring before I check this, though.  I also plan to replace fuel pump as regular maintenance, since that has never been changed in the five years we've owned the car.  Car has plenty of power and accelerates smoothly, though.

Checking fuel pressure would be an easy thing to check.  Where do I tap in with a test gage on the H6 engine?

[FerGloyale]

11 hours ago, Ken2004LLBean said:

The intake is the one that came with the salvage yard engine, although my mechanic said he kept the engine wiring harness from the old engine b/c it was in better condition.

I was thinking that the dreaded fuel pump cap/O-ring issue might be starting to rear its ugly head.  The car starts fine most of the time, but maybe 1 out of every 5 starts or so, I will have to crank it twice to start it; this could happen when engine is cold or hot.  I will have to purchase a replacement cap and O-ring before I check this, though.  I also plan to replace fuel pump as regular maintenance, since that has never been changed in the five years we've owned the car.  Car has plenty of power and accelerates smoothly, though.

Checking fuel pressure would be an easy thing to check.  Where do I tap in with a test gage on the H6 engine?

it Doesn't make sense that the mechanic would have swapped wiring from the original intake onto the used replacement one.  Unless he was wholly unfamiliar with the main, large engine wiring connectors. and removed all wiring from intake one sesnor/solenoid at a time. I am going to say that the problem is with a sensor or solenoid on the manifold, or a problem with the wiring connecting to it.  

The reason it doesn't make sense is why would he use the JY intake, but take the time to swap the wiring from one to the other?  More work for no gain.  The intake has to be removed to swap the wires so why not just drop the original intake complete onto the replacement engine?  What you are experiencing is exactly why you should never trust the intake/wiring/sensors from a Junkyard engine.  Most of the times the warranty terms specify that only the longblock is covered.  All of the other items a left on for "connivence" for the wrecker.  Lots of times I get engines with minor damage to intake/wiring/accessory brackets etc.  Doesn't matter cause you are supposed to use all of the stuff Original to the car and only swap longblocks

at any rate test fuel pressure with a t fitting at the fuel filter.  

[Ken2004LLBean]

Well, the mechanic who did the engine swap is no longer my mechanic, as I caught him in a few lies, including tampering with my instrument cluster to disable the check engine bulb because he couldn't figure out the problem causing it to illuminate.  So, I don't take his word as gospel, and you're right, his statement doesn't make sense.

Your point on not trusting wiring from junkyard engines is well taken, and a hard lesson I've learned, although if I had to do this all over again, I would have just junked the car after the original engine blew, and used the money to buy a different car, but this mechanic assured me replacing an engine was a good move, as the car is otherwise mechanically good and has a solid body.  I will never swap another engine in a computerized car with all sorts of emissions crap; I would only do it on a pre-1980 American car.

At any rate, I've spent too much on this car to give up now.  Aside from the check engine light and idle issues, it runs and drives well, and by a miracle, passed emissions last month, so I don't have to clear that hurdle for two years.

Besides being invested financially, I'm invested emotionally, not wanting to cave in from a challenge.  If nothing else, it will make me a better amateur Subaru mechanic.

Ken

Edited April 10, 2019 by Ken2004LLBean
typo

[FerGloyale]

4 minutes ago, Ken2004LLBean said:

I will never swap another engine in a computerized car with all sorts of emissions crap; I would only do it on a pre-1980 American car.

 

If he had swapped all the original intake parts onto it that would have been fine.

Nothing wrong with making an engine swap.  It just needs to be done the right way.

[Ken2004LLBean]

That would have been more work for him, lol. Now I get to do more work, rather than enjoy the car.  Bummer.

The car never had weird idle surges or a persistent CEL prior to the swap, but it always did seem to idle a bit high (closer to 800 rpm, than the desired 600).  Anyhow, too late to get the intake off the old engine at this point.

Guess I'm fooked now.  I might remove the fuel pipe protectors to get more access to the fuel and vacuum lines.  I read that fuel injectors have O rings that can leak and cause high idle.

 

Edited April 10, 2019 by Ken2004LLBean

[FerGloyale]

9 hours ago, Ken2004LLBean said:

That would have been more work for him, lol. Now I get to do more work, rather than enjoy the car.  Bummer.

 

Actually, he did more work by removing wiring and sensors one at a time if that's what he did.

The entire intake comes off with the harness attached, and makes accessing the TC bolts easier.  If he finagled those bastards in without removing the intake, he definately spent alot of uneeded time.

[Ken2004LLBean]

It was his first h6-3.0 engine swap. It took him forever, even considering he undoubtedly worked on other cars in between doing my engine swap, so he probably did it the hard way.