Sluggish acceleration and loud air intake - Subaru WRX Forum
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post #1 of 11 Old 04-24-2017, 01:14 AM Thread Starter
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Sluggish acceleration and loud air intake

Hey folks, I have a 2007 WRX with stage 1 mods and a tune for the high intake air filter. I bought it last summer as rebuilt status and have been fixing various issues with it since.

A play by play of my current problem:

Months ago, a CEL comes on for "secondary air pump valve stuck closed". I disable the CEL and hope since it is stuck closed there won't be too many problems.

After a few weeks the air pump starts squeeling when I do a cold start. After reading up what it costs to replace I opted to buy blocking plates so I can just take the air pump out, cheaper than replacing.

Ever since the CEL came on the first time I have noticed slow acceleration performance and the high intake air filter taking in much more air than it should be only to barely keep up with cars in front of me taking off after a red light.

I brought the car to a shop to take out the air pump, twice because we didn't take enough parts out the first time. Both times after getting the car from the shop, the car performed beautifully for the first couple of days after, only to perform sluggish again thereafter. This part makes me seem crazy, especially since the mechanic said he really didn't do anything but take the air pump out.

My best guess is: some sort of an O2 sensor is misreading the air flow because of the busted or missing air pump and tells the ECU it needs more air, thus the louder than normal air intake, and perhaps the car is running rich? Not sure.

Has anyone experienced anything like this? Any help would be greatly appreciated.
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post #2 of 11 Old 04-24-2017, 10:55 AM
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Louder intake swoosh sound and low or fluctuating power is a good indication of a boost leak.

Another thing to check is when the air pump is deleted incorrectly, and the valve that holds the barometer ( altitude sensor) is removed, your car will have a significant set of issues because the sensor goes to default high altitude and your ecu sets all altitude compensations to boost, fueling and timing to max.

The way to check is to monitor your altitude with an access port if you have one.
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post #3 of 11 Old 04-24-2017, 10:43 PM Thread Starter
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Thanks for the quick and helpful response!

I think (hope) you're on to something with the second point you made. Sounds easier than fixing a boost leak! I've attached a photo of the parts removed when deleting the air pump. If I'm not mistaken, those two silver chunks are valves, and one of them contains the barometer? If that's the case, I'm guessing I should make another appointment to get it reinstalled. Is there a way to identify which one is the correct one?

Also, when disabling the the CEL's I just blanket disabled anything related to the secondary air pump system (like 10 codes), was this the right move?

I don't have an access port but I have a Tactrix cable and a laptop so I should be able to log altitude on there. Is it supposed to record accurate, literal altitude? If so I know what to look for. I'll check it out shortly.
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post #4 of 11 Old 04-25-2017, 08:52 AM
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You know there are multiple "air pump delete DIY"s out there, right? They tell you what to do and NOT to do. Air pumps are for emissions, and Ruso is right the ecu is comping by changing tables for a default value. You need a tune to comp for the deletes, and you might as well decide if you want to delete one or both of the pumps, which depending on your state inspections laws you may need one left on (if you have two).
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post #5 of 11 Old 04-25-2017, 10:58 AM
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Robo, you can't tune for a missing barometer ��.

Paull, in your box, there are three items. The valve on bottom left contains the barometric sensor. It's the plastic part on top.

You can plug in the whole valve into the harness and zip tie it to something for a quick fix, just make sure it's not bouncing around and hitting the block.

A better way to do it, is to very carefully cut the plastic sensor off from the metal body. Please find a diagram of how to cut. That's what I did, then just wrapped in electrical tape and plugged into the harness. Works like a charm.
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post #6 of 11 Old 04-27-2017, 10:21 AM
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I forgot one of the pumps had that baro, silly emissions. Doesn't the 255 still have a MAP next to the TB?
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post #7 of 11 Old 05-08-2017, 09:21 PM Thread Starter
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Thanks for the tips! I had the valve with the baro "reattached" and plugged back in.

But alas, the very same thing happened again. The first day or two back from the shop the car ran perfectly: super responsive, consistent power, quieter air intake. Over the next couple of weeks the performance has degraded back to sluggish, the swoosh noises unnecessarily loud and happening way too early, and inconsistent/slightly jittery lower speeds.

I reflashed the ECU with the same map it had before that has a good rep (Gabedude's A8DK100X - MY07 WRX Stage 1 - R29) and followed an air-pump delete tutorial to make sure I have the exact right CEL codes disabled first.

I logged the atmospheric pressure to ensure plugging the baro back in worked (Tactrix cable + RomRaider), and the value appears to be perfect for my area (Victoria, BC: 14.8 psi).

Do either of you know if there is much use in posting the rest of my recent log .csv's on this forum? I have a rough idea of which metrics I should be logging in general, but don't have much of an idea which values are good or bad.

I'm also open to any other ideas. I'm super curious how the car can very clearly perform great for several days, or what triggers it to perform great (reflashing the ECU doesn't seem to do much). Also, could it still potentially be a boost leak even with this off couple of days with good performance?
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post #8 of 11 Old 05-09-2017, 03:34 AM
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My money is still on a boost leak bro!

Boost leaks can be funny and create all sorts of weird symptoms.

"the swoosh noises unnecessarily loud and happening way too early, and inconsistent/slightly jittery lower speeds" definitely falls in line with them.

Check all of your silicone couplers and clamps from your intake all the way to your throttle body (everything underneath your intercooler and at the throttle body are the most likely).

Unless there's something wrong with your boost control system that's the most likely situation.
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post #9 of 11 Old 05-19-2017, 02:40 PM Thread Starter
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Thanks for the tip, I took the car into a shop in town that specializes more in tuned cars, here is what was found:

They checked for boost leaks but the car was actually fine there. What they did notice was the Mass Airflow sensor was not mounted properly (too long of bolts). I bought the car as rebuilt status last year and the guy that fixed it up initially probably did this (he did a few sketchy things). So the shop fixed that issue and test drove it and found that if the car hits 5000 RPM it limits the RPM and a CEL comes on for the turbo wastegate sensor not functioning properly (or something to that effect). They replaced that part, but the same RPM/CEL issue still occurs.

They did some online digging and suspect that there may be a glitch with the generic tune I gave it (Gabedude's A8DK100X - MY07 WRX Stage 1 - R29) for my particular car. They suggested I buy a Cobb AccessPort which comes with a more reputable stage 1 tune and go with that. In he mean time they suggested reflashing with a stock tune and don't drive aggressively until then.

So that's where things are at currently. They fixed a couple of sensors which is good but I now have this CEL at 5000 RPM issue which may or may not be fixed by a different tune. I'll have to save up for a bit for that AccessPort if that's the direction I decide to go, but ~$1000 CAD is a big price to pay for something that may not even work. It's times like these I wish I lived in a bigger city where I can go for a pro tune!
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post #10 of 11 Old 05-19-2017, 03:03 PM
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Quote:
Originally Posted by paull View Post
Thanks for the tip, I took the car into a shop in town that specializes more in tuned cars, here is what was found:

They checked for boost leaks but the car was actually fine there. What they did notice was the Mass Airflow sensor was not mounted properly (too long of bolts). I bought the car as rebuilt status last year and the guy that fixed it up initially probably did this (he did a few sketchy things). So the shop fixed that issue and test drove it and found that if the car hits 5000 RPM it limits the RPM and a CEL comes on for the turbo wastegate sensor not functioning properly (or something to that effect). They replaced that part, but the same RPM/CEL issue still occurs.

They did some online digging and suspect that there may be a glitch with the generic tune I gave it (Gabedude's A8DK100X - MY07 WRX Stage 1 - R29) for my particular car. They suggested I buy a Cobb AccessPort which comes with a more reputable stage 1 tune and go with that. In he mean time they suggested reflashing with a stock tune and don't drive aggressively until then.

So that's where things are at currently. They fixed a couple of sensors which is good but I now have this CEL at 5000 RPM issue which may or may not be fixed by a different tune. I'll have to save up for a bit for that AccessPort if that's the direction I decide to go, but ~$1000 CAD is a big price to pay for something that may not even work. It's times like these I wish I lived in a bigger city where I can go for a pro tune!
Doesn't sound like your shop specializes in Subies.

Sounds like what you're saying is that as you go and accelerate hard the car spools up and then above 5k rpm just hits a wall of power. Does it feel like there's a hard drop in power? Like you're hitting a wall? And is the code Wastegate Solenoid Performance too High? It's P0244 I think.

If so, you have a boost control issue (obviously) and are hitting the overboost condition. It's not a boost control solenoid issue but either the plumbing of the vac hoses to the solenoid/wastegate OR spring pressure on the wastegate actuator OR missing restrictor pill in one of the lines.

First, the simple check. Visually inspect the boost control hoses and make sure the restrictor pill is there by squeezing the vac hoses and that it's on the right hose.


Here's an article about how the boost control on our cars works:
https://www.cobbtuning.com/support/h...m-works-v1-09/

If all is good here, put the factory map back on and see if you continue to overboost. If so, it is most likely that someone adjusted the wastegate actuator arm (I'm assuming your car is running the td04 turbo (stock on your year)... and you said Stage 1 so.

The good news is that most fixes for this are cheap. The one blatantly annoying situation is if someone has adjusted the arm. If so, you're going to have a headache and will either have to get a replacement actuator (from the same turbo), a protune, or keep adjusting it back and forth (keeping track of how far you have gone) until you find where it was set to from the factory.

Tip for anyone reading this: NEVER EVER adjust the wastegate actuator for ANY reason. It does NOT serve as a way to compensate for boost control error. It also breaks the relationship between wastegate duty cycle numbers and the actuator movement in a non-linear and totally unpredictable way rendering any off the shelf map useless.

Good luck!
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post #11 of 11 Old 05-20-2017, 08:57 AM
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As much as I love my APv3 from Cobb, they no longer allow you to bypass emissions devices or codes. I'm going to be switching to OS after I fix a few other things but yeah, don't go Cobb for tuning. Search around for other OS tunes for your setup or even check out the e-tunes from reputable tuners online.

E-tunes are a type of protune that you get after talking to the tuner via email/phone, you send them logs (wideband preferred) and they send you a tune based on the logs/comments and revise it until you are happy. Revisions aren't always free though but it's better than a dyno tune for one sole reason, you're getting a road tune for your area, weather condidtions, and other environmental characteristics.

I do have a friend who does OS tuning near me but before that I was highly considering getting an e-tune for a basemap until I get a Wideband as I'm having issues reflashing my ECU with the APv3 lately (voltage drop even when being charged/jumped).


Post up your logs in XML format if you can, all logs can be read in that format even if it's OS/Cobb software that was doing the logging.
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