Stuttering/bogging under load UNDER 2k rpm

[Danteandsoob]

So this what I said from a previous thread. I'm starting a new thread for anyone that might have the same issues (it seems like quite a few people have had these troubles this winter.)

So previously, I stated that I would check all the vacuum hoses and TPS specs. This was in a thread about how I wanted to put a WRX fuel pump in my car. Works fine, but wasn't the cause of my stuttering/bogging.

So today I cleaned the MAF with MAF cleaner, still didn't help. After that I changed the spark plug wires with an existing pair to see if the pair on the car was torn some where. Still nothing. Tonight I will change the airbox to the 90* style and see if that helps.
I don't think the TB cooent bypass would affect anything because cooler air in is always a good thing.

Update: so I went home and changed the 45* to the 90*, swapped out the MAF from the other car, and cleaned that one as well. Absolutely nothing changed. Every vacuum hose was perfect as well so that's not it either.

One thing I noticed was that It bogs/stutters UNDER 1800 rpm. After that it's totally fine. Any ideas what else I can check??

2nd update: so I just randomly searched "ej22 bogging under 2k rpm" on Google and found some things that may have been said on here before.
Some people have reported these same issues and can be attributed to 4 major items.
-MAF sensor
-spark plugs and/or wires
-front oxygen sensor
-knock sensor

So as I've done the first 2, I will be trying the last 2 tonight and reporting what happens. I think it is the oxygen sensor because people online have been saying that under 2-3k rpm, the O2 sensors are on a "closed loop" and because this range is where my car has trouble, I believe it to be the problem.

[mike-tracy]

Are you resetting the ecu the "right" way between changes? Also, did I miss you mentioning changing out the ECU's Coolant Temp Sensor? Its a long shot, but it does affect the ECU's decision making a lot.

[Danteandsoob]

What's the "right way? And no, where is that sensor?

[mike-tracy]

The procedure to clear codes is related to checking them, I can't remember off hand the exact procedure.

2ndly, the coolant temp sensor is located on the big "crossover pipe" underneath the intake manifold. The sensor with a single wire is for the gauge cluster, and doesn't affect the ecu. It's the other one with the actual plug on it. I feel this is a long shot, and your issue stems from bad grounds (assuming your MAF, injectors and ecu are good).

[Danteandsoob]

I have cleared and checked for codes this way once before, but when the car was fine. I was just unplugging the battery negative cable, but will do this correct procedure today if I get the chance. I know it sounds weird but I really hope I get a code when i do it today; I just want this crap to be fixed.

So along with checking codes, I've narrowed the problem down to:
-checking oxygen sensor (actually pulling it out of the cat.)
Or,
-checking the knock sensor

Yesterday and today have been especially bad. I can really feel the timing having a retard-ish feeling it. Like, when I try and floor it after I've gotten over 2k rpm, it just feels like its chocking/straining/dying. It's a pretty shitty feeling.

[Danteandsoob]

So if I had bad grounds, where should I check for those bad grounds first?

[Danteandsoob]

Checked Knock sensor, nothing. Checked codes, nothing. Still reset the ECU just cause. Should I post a video of what it's doing exactly? Would that help at all?

[Danteandsoob]

Replaced fuel filter at the advice of a friend who has a very good knowledge of subarus. still nothing. going to check the pump when I get home.

[Danteandsoob]

Video: http://vimeo.com/118944992#t=5s

[mike-tracy]

I'd clean all the grounds in the engine bay. You may want to make your own grounding kit additionally.

[Legacy777]

I couldn't hear the engine, but if you had it floored and the rpms weren't raising then something is definitely wrong (obviously). If you accelerate with less throttle, does the RPM's go up?

How did you test the knock sensor? Try disconnecting the knock sensor electrical connector and see if that makes any difference. Do the same with the O2 sensor.

You can do this for some other sensors as the ECU goes into fail-safe mode, which at least makes the car drivable. This is an alright way to do some diagnostic testing.

[Danteandsoob]

I couldn't hear the engine, but if you had it floored and the rpms weren't raising then something is definitely wrong (obviously). If you accelerate with less throttle, does the RPM's go up?

How did you test the knock sensor? Try disconnecting the knock sensor electrical connector and see if that makes any difference. Do the same with the O2 sensor.

You can do this for some other sensors as the ECU goes into fail-safe mode, which at least makes the car drivable. This is an alright way to do some diagnostic testing.

Less throttle, it's totally fine. I tried unpluging the knock sensor and 02 sensor (not at the same time) with no positive results. I did how ever replace the 02 sensor and the car runs even worse now.

[Danteandsoob]

I really need some help on this, the car is getting worse and worse by the day.

On cold starts in the morning, the car will not even get out of the driveway and it feels like it's not getting enough fuel. This lasts for about 5 minutes before it starts acting normal. I have replaced the fuel pump and fuel filter. EDIT: replaced spark plugs, fixed the misfire.

Brand new Bosch O2 sensor. Getting a new knock sensor. Should i still replace the coolant temp sensor?

I cleaned all the grounds last night, and I have had a ground kit on the car for 2-3 months now.

I checked for codes after resetting the ECU after installing the new O2 sensor, and did not get any codes.

[Legacy777]

How old are the spark plug wires?

I would replace the coolant temp sensor if it's old and unknown age.

[Danteandsoob]

Old spark plugs were around 8-10k, replaced with brand new V-powers. Yeah, I was thinking of just replacing it anyways.

[Legacy777]

What about the spark plug wires?

[Danteandsoob]

oh shit, I'm dumb. wires only have around 3-4k miles on them.

[Legacy777]

What type of plug wires are they?

Can you refresh my memory on when you first started having these issues?

[Danteandsoob]

Blue NGK's.

The issue probably started around October 2014. When it started getting colder is when it would have issues. Warmed up it was alright, but still bogged under 2k. I've been reading around and it seems like my fuel pump grounds might be the issue. Where the r22 connector is.

[Danteandsoob]

Replaced knock sensor, bypassed r22 ground, and checked for fuel pressure from the pump when primed. All checked, and failed to fix this problem. I'm just about ready to take this car to the dealership or the Subie specialist in town and see what they can do.

[RoughDiamond]

In your video, the coolant temp is pretty low. Is that "warmed up"? It almost seems like it's overfueling (DUMPING fuel on WOT) but the power light comes on which means the ECU and TCU acknowledge a WOT condition, it's just not happening at the right time.

I'd check valve timing and cam/crank sensor condition (not coated in oil, still have the shielding, ect). Also check for AC voltage. Anything above .5V is an issue. My Loyale was doing the same thing (but above 3K) when the diodes fail to rectify. Would cause the bog, jumpyness, ect, so something to look as well.

[Danteandsoob]

That is not warm up coolant temps, I just recorded the video after I got out of a 2 hour class.

See, I'm also thinking it's the timing as well! I will have to pull out the sensor to check it.

Where do I check the AC voltage at?

[RoughDiamond]

Yeah, pull the crank sensor and the L/R timing covers to check for sprocket/mark alignment.

You can check right on the battery terminals, just grab a decent multimeter, set it for 2 (or 5) VAC and leads to the terminals. Any sort of AC voltage will completely screw with the sensor inputs to the ECU and the ECU itself, causing very odd behavior.

[Danteandsoob]

Yeah, pull the crank sensor and the L/R timing covers to check for sprocket/mark alignment.

You can check right on the battery terminals, just grab a decent multimeter, set it for 2 (or 5) VAC and leads to the terminals. Any sort of AC voltage will completely screw with the sensor inputs to the ECU and the ECU itself, causing very odd behavior.

So I checked all of these today.

I believe the timing is okay, but im not for sure.
I checked and cleaned the sensors and boy were they dirty. not oil or gunk just dirt and rust.
And the AC voltage seems to be okay.

So this leads me to still thinking its a fuel issue.

[Legacy777]

Did you just bypass the fuel pump ground wire on the fuel pump connector under the seat or did you also do the power lead?