2003 wagon hesitation - Subaru WRX Forum
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post #1 of 20 Old 04-13-2012, 12:31 AM Thread Starter
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2003 wagon hesitation

Hi! This is my first post on the site, though I have lurked around for awhile. I know that the topic of hesitation has many posts, and I have tried to get as much as I can from these before posting my own. However, I've been troubleshooting this problem for awhile, and I can't seem to figure it out. My car is a 2003 wrx wagon, stock except for a cat back exhaust. 95k miles.

The issue that I am having is hesitation under load above 3500 rpms or so. In first gear, the car feels good and pulls hard above 4500. The car seems to pull fairly well in 2nd gear as well, no hesitation; it doesn't pull quite as hard as in first though. In 3rd, I seem to get good turbo spool at partial throttle up until about 3500 or so. Above 3500, at partial or WOT, I get hesitation all the way to the end of the tach. Same deal in forth and fifth; car feels good until I get over 3500. The hesitation isn't violent, it just slightly jerks through the tach and doesn't pull very hard.

I don't have a boost gauge or wideband, so I have no troubleshooting tools now. Here is what I have done:
replace spark plugs (stock Pt plugs, gapped to 0.030)
replace PCV
check for vacuum leaks (I'm about 90% sure there aren't any)
checked all intake connections
put fuel system cleaner into current tank
disconnect front O2 sensor (hesitation still present)
disconnect MAF (car died)
stock air filter (about 7k miles on it)

Sorry for the long post, but I would appreciate any input that you guys can give.
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post #2 of 20 Old 04-13-2012, 06:48 AM
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Switch out the stock BCS (maybe with a buddy) just to rule it out. Did you CLEAN the MAF?

Did you do anything the previous months leading up to the problem? Or has this always been an issue.

Paul
2002 WRX Sold
2007 WRX Sold
2007 STi totaled
2007 Foz XT sold
2007 MS3
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post #3 of 20 Old 04-13-2012, 10:27 AM Thread Starter
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I forgot to mention that I threw a lean bank CEL, which went away after cleaning the MAF and resetting the ECU, until last nite, when it came back. This has not always been a problem, just within the last month or so. I've also replaced the fuel filter recently. I'll try to get my hands on a BCS to try out; is there any way to diagnose the old one?
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post #4 of 20 Old 04-13-2012, 10:53 AM
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Does the car have a boost gauge? If so what boost are you showing in the trouble gears? Crap. Just re read and saw that you don't.

Kevin.
Cobb ap stage 2 ots, catless uppipe, catless turboback, Cobb Sf intake.

Last edited by bad grocerygetter; 04-13-2012 at 10:54 AM. Reason: oops
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post #5 of 20 Old 04-13-2012, 11:53 AM
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Quote:
Originally Posted by cobra280z View Post
I forgot to mention that I threw a lean bank CEL, which went away after cleaning the MAF and resetting the ECU, until last nite, when it came back. This has not always been a problem, just within the last month or so. I've also replaced the fuel filter recently. I'll try to get my hands on a BCS to try out; is there any way to diagnose the old one?
Not sure on the diagnoses of the stocker (look on nasioc) It's easy enough to just take out and slap another in (IMHO). I have heard of connecting the green test connectors and then cleaning the lines (have never done this myself) I always had access to another stocker for diagnoses.

Which fuel filter did you replace? The front or rear?

Have you checked for boost leaks yet? Smoke test ?

Paul
2002 WRX Sold
2007 WRX Sold
2007 STi totaled
2007 Foz XT sold
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post #6 of 20 Old 04-13-2012, 08:37 PM Thread Starter
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I haven't yet done a smoke test, though I am thinking of making a DIY pressure test to check for leaks with soap and pressure. I tested my BCS today, by giving it power directly from the battery. It seems ok; it opened and allowed air to pass when power was applied. I'm still gonnna try to find someone to let me borrow one for a few minutes, though.
I replaced the fuel filter up front; I didn't know there was one in the rear (unless you are referring to the fuel sock).
As an interesting note, while trying to diagnose the TCS, I put a spare restrictor pill in the line going to the wastegate actuator. This made the car feel much more powerful in 1st and 2nd and greatly reduced the hesitation in 3rd, though the power wasn't great. I've now removed it, since I was probably overboosting a little. I'm not sure why the hesitation seemed less with the pill in there, maybe you guys have some ideas? Thanks for the responses
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post #7 of 20 Old 04-14-2012, 10:18 AM
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Look for a boost leak first, did you clean the BCS?

Yes, the sock (rear).

Paul
2002 WRX Sold
2007 WRX Sold
2007 STi totaled
2007 Foz XT sold
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post #8 of 20 Old 04-15-2012, 10:35 PM Thread Starter
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I did spray out the ports for the BCS, so they should be clean.
I will be pressure testing my intake and boost system tomorrow morning to check for leaks using a DIY pressure test attaching to the intake after the MAF. I've been trying to figure out which hoses I need to plug off in order to do the test properly. After doing some reading, it seems that I need to plug off: 1. the PCV connection to the intake just prior to the turbo 2. The line going to the BCS from the turbo and 3. the PCV line on the front side of the intake manifold that leads to the crankcase.

Does this sound correct? I'm going to remove the oil fill cap, just to be safe.
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post #9 of 20 Old 04-16-2012, 07:01 AM
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Sounds about right.

I personally like smoke tests if you have access to a fog machine.

Paul
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2007 STi totaled
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post #10 of 20 Old 04-20-2012, 11:20 PM Thread Starter
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I just finished pressure testing the intake, and found no vacuum leaks. I've also done a fuel pressure test, which came back just over spec. At idle, with the vacuum hose connected, I get about 39 psi (spec is 30-34). And with the vacuum hose disconnected, I get 50 (spec is 41-46). So I'm not quite sure what this means (clogged fuel return line?), but I'm not sure that it would be causing the issues that I'm having. Don't really know where to go from here.
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post #11 of 20 Old 04-20-2012, 11:38 PM
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Clogged fuel line or injector. Have you cleaned the IACV yet?

Paul
2002 WRX Sold
2007 WRX Sold
2007 STi totaled
2007 Foz XT sold
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post #12 of 20 Old 04-20-2012, 11:48 PM Thread Starter
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I haven't cleaned the IACV yet, I thought thought would only affect the idle performance, which is perfect currently. I was thinking it could be an injector too, though I hope that's not the case.
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post #13 of 20 Old 04-20-2012, 11:55 PM
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Its not a thing to clean em out,,,, although if one was jacked you are SOL (not really)for it.

What plugs did you use? NGK's?

Paul
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2007 STi totaled
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post #14 of 20 Old 04-21-2012, 12:03 AM Thread Starter
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Yea, I used NGK's. How do you clean the injectors, without sending them somewhere to have it done?
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post #15 of 20 Old 04-21-2012, 12:10 AM
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Other than taking them out and manually doing it with seafoam, send them out to Gordon at Witchunter.com

Forgot to ask, have you owned this car for a while? What boost are you seeing in these pulls?

You can actually take the inj's out and hook to a ground and power to see if they are even working (you should hear a clicks)

Paul
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