H6-3.0 fuel pressure regulator question - Subaru Outback - Subaru Outback Forums
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post #1 of 13 (permalink) Old 04-07-2019, 04:44 PM Thread Starter
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H6-3.0 fuel pressure regulator question

I have been fighting a high idle issue, but so far, have been unable to find any vacuum leaks. I saw on another thread that the fuel pressure regulator on the H4 engines of the same vintage have a vacuum hose attached to them.


Do the H6 engines also have a vacuum hose attached to the fuel pressure regulators? If so, does anyone have a photo of what the FPR looks like on the H6? I assume they are under the fuel pipe protectors.


If they do have a vacuum hose, that would be one more avenue of chasing down a possible vac leak.


Ken


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post #2 of 13 (permalink) Old 04-08-2019, 12:57 AM
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High idle is most likely a dirty idle air control valve. They can be cleaned. You will need to purchase a new gasket. The screws can be a pain. I recommend the largest flat head screwdriver you can fit in the screws.

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post #3 of 13 (permalink) Old 04-09-2019, 10:24 PM Thread Starter
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Appreciate the response. I have replaced the IAC with a new OEM one from the dealer (but I suppose it's always possible the new one could be defective). I have two used ones that I have cleaned and may try swapping to see if they make a difference. As for the screws, I chucked the original ones, and used stainless steel allen-head screws (a suggestion I saw on one of the Subie forums); these are much easier to deal with, no worries about stripping the screws, and look cool too!

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post #4 of 13 (permalink) Old 04-10-2019, 10:41 AM
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I would not expect a new IAC to be faulty. Can you log OBDII data? What is the idle speed? Any check engine lights?
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post #5 of 13 (permalink) Old 04-11-2019, 10:58 PM Thread Starter
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Quote:
Originally Posted by Glennda5id View Post
I would not expect a new IAC to be faulty. Can you log OBDII data? What is the idle speed? Any check engine lights?

Check engine light is constantly on. After the initial cold start high rpm (which is normal), idle speeds in partly warmed engine are about 850 in park, 750 in drive. Idle speeds in fully warmed engine are 1,000 in park, 850 in drive.


I don't currently have data logging capability. I can retrieve freeze frame data, or take a photo on my phone of live data on my very basic, $40 scanner.


I may look into ROM Raider program, which seems to be popular among Subie enthusiasts, although I have no interest in tuning/modding. I just want a stock engine that runs properly, with no damned check engine light.

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post #6 of 13 (permalink) Old 04-11-2019, 11:56 PM
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You need to get the codes....
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post #7 of 13 (permalink) Old 04-12-2019, 07:00 AM
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Quote:
Originally Posted by Ken2004LLBean View Post
Check engine light is constantly on. After the initial cold start high rpm (which is normal), idle speeds in partly warmed engine are about 850 in park, 750 in drive. Idle speeds in fully warmed engine are 1,000 in park, 850 in drive.


I don't currently have data logging capability. I can retrieve freeze frame data, or take a photo on my phone of live data on my very basic, $40 scanner.


I may look into ROM Raider program, which seems to be popular among Subie enthusiasts, although I have no interest in tuning/modding. I just want a stock engine that runs properly, with no damned check engine light.
I use free rom-raider on both my cars.

$10 vag cable, windows laptop, and it works pretty good for logging / diagnostics.
(a little slow on connecting,...but I did not spend $168 on a tactrix like the turbo people must do to upload code).

? Want people to stop needing to ask what exact car you have? year -model -engine -trans, scroll down to "your car":
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Found a Subaru Vin Decoder (also works on many manufactures):
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post #8 of 13 (permalink) Old 04-12-2019, 08:37 AM
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High idle on the EZ30D could be a damaged IAC or the throttle cable is sticking. Could also be carbon build up on the throttle body and plate and it's neither of the first two, just a stuck open plate.

Another thing would be erroneous feedback from the ECT sensor and the ECM is trying to warm up the engine. Or you could have a stuck open thermostat and the engine isn't warming up good.

These cars drop the idle once the shifter is moved from Park regardless of cold temp start, but will keep the idle up to warm the engine. This keeps the transmission from kicking in to gear hard. The ECM sees a shifter move from park and expects you to put it in gear so it drops the idle speed.

The AC function also determines idle state. If the AC is on, the ECM bumps the idle up to compensate for the mechanical load and electrical load. Usually the ROM is set for a 100 rpm bump from normal.

If these engines develop a vacuum leak, the ECM will correct the idle by closing the IAC down. Since it's MAP run, speed density, it's hard to tell when there's a vacuum leak except when that leak creates a misfire or alters the fuel trim on one side of the engine in comparison to the other side. You could drive the car for years with a vacuum leak and not know it.

Codes would be nice.

Logging would be a plus. If you log data, log AF 1 & 2, AF Correction 1 & 2, RPM, Engine load, MAP, Coolant temp, Knock correction and rear O2 sensor. That will give a clue as to what is going on. After you log, put the log in a zip folder and upload the zip folder as an attachment to a post.


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post #9 of 13 (permalink) Old 04-12-2019, 11:27 AM
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In a previous thread OP has mentioned codes P0519 and P0507

OP--it would be helpful for all I think if you tried keeping all the issues you're hoping for help sorting out in one thread. Multiple threads on the same issue with critical information scattered between them doesn't help us at all.

That said, I still think you need to smoke test. I know you said your mechanic had done so, but, I'd want to verify there's no vacuum leak. Once you're confident there's no vacuum leak, I think you should give the wiring the wiggle test. You've thrown new parts at the car, including the IAC and the ECU, but it hasn't fixed those codes. The only other thing is the wiring between the two and if you're not rigorously testing the wiring before you go any further, you could be chasing your tail endlessly.

If I recall correctly, this is a new to you engine that you guys stuffed in your car. I've personally had an issue where the connectors inside the bulkhead connector--the connector connecting the cars main wiring harness to the engine wiring harness at the back of the intake manifold--get wallered out and make intermittent connection. This could have easily been caused when disconnecting or reconnecting the harness at a slight angle.

The dealer chased this simple wiring issue for months with the previous owner, throwing multiple o2 sensors at the car as well as even going as far as even replacing the ECU. Sound familiar?

Check your wiring.

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post #10 of 13 (permalink) Old 04-14-2019, 08:02 PM Thread Starter
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@cardoc:

I've noticed that the idle does NOT increase when I turn the A/C on; this, however, could be due to the A/C compressor not turning on (possibly due to low freon charge?). The A/C has never been cold in the five years we've owned the car. The idle drops down slightly (about 50 rpm) when you turn the steering while while the car is stationary (I know that puts a lot of stress on the steering system, but just did it briefly to see if the ECM would respond).

IAC valve is a new, OEM part. Throttle cable is properly adjusted and does not seem to be binding. Throttle body has been cleaned. Throttle plate does not seem to be hanging up.

As for data logging, I'm not that technically (computer) saavy, although if I don't resolve this problem soon, I suppose I will have to learn to do that.

@aesthetic.rake:
My apologies for scattering threads; I can see how it can be confusing. Even I'm forgetting how many I started.

I plan to do further testing for vacuum leaks. If I remove the fuel pipe protectors, it will give me more access to the bottom edges of the intake manifold runners, and possibly some of the tubing under the manifold as well. Instead of a smoke test, I am going to do a propane test, and make a wand out of 1/4" copper tubing that I can bend to help me get under the legs of the intake manifold.

As for the wiring: Yes, you are correct, the engine was replaced with a used engine in November of last year. Had an issue with a pushed-back pin in connector to the right-front O2 sensor and got code related to O2 sensor heater circuit, but I pushed that pin back and have not had that code since.

Recently, I tested for voltage, continuity and resistance between the ECM and sensors in question, and the wiring seemed to check out. More recently, I took apart and cleaned (with QD electrical contact cleaner) the engine/bulkhead wiring harness connectors, as well as the connectors at the sensors. Although I did not see any bent/broken pins, or corrosion, cleaning and reassembling the connectors made a definite improvement, lowering my idle speeds by 50 to 100 rpm, both hot and cold engine, so that makes me question if this is a wiring issue, instead of a vacuum leak. I have not tried wiggled the connectors, though, while the idle speed is surging, to see if that makes the engine act normally.

Or, I could have both a vacuum leak and electrical issue .... ggrrrrr.


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Last edited by Ken2004LLBean; 04-14-2019 at 08:05 PM. Reason: Add info
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