Surging and over boosting in 3rd and 4th gear. Please Help!
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This is a discussion on Surging and over boosting in 3rd and 4th gear. Please Help! within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Ok so to start off my car is a 2002 WRX with about 120,00 miles on it. about 10,000 miles ...

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    Exclamation Surging and over boosting in 3rd and 4th gear. Please Help!

    Ok so to start off my car is a 2002 WRX with about 120,00 miles on it. about 10,000 miles ago I did the timing belt, transmission fluid, diff. fluid, plugs, fuel filter, and had the fuel pump checked. About 5000 miles ago i noticed that in 4th and 5th gear if I would accelerate there would be this surging as it was accelerating. Almost sounded like it was hitting the rev. limiter but then would keep going. I checked the plugs, and coil packs to make sure nothing was loose. The things that are done to the car is a catless up pipe for the turbos sake and catless open downpipe(However before the down pipe I was still having the issue). I have on some occasions immediately following a fill up throw a P0171 for Bank 1 too Lean, but after clearing the code it would not come back for multiple fill ups. Just to be sure I again changed the fuel filter and plugs and then also replaced the o2 sensor and MAF. After changing those this its new symptoms. 1st gear pulls strong with no issues on boost. In second it pulls good, but at around 4500 there is a very slight hesitation but nothing that is very pronounced. Now 3rd and 4th is where it gets interesting. Both have a lot of hesitation as it accelerates almost like boost is being cut. In 3rd boost is spiking to around 16 lbs which is really scary. At this point it makes me think it is the waste gate and it is not opening and and it is just sticking all over the place which causes the hesitation/surging feeling. In 4th gear however when it surges and it loses boost the sound is almost like its detonating, but it is very hard to tell. By far 4th gear is the worst feeling and I can't even make 7 pounds of boost. Obviously I cannot get a good 5th gear pull just for safety. I am hoping to check the waste gate, fuel sock and sending unit(was not able to do it before), leak down test, and hook up a good vacuum leak tester by putting pressure to the system. If anyone else has any ideas of what I should check or what it could be please let me know. I do not want to keep buying parts and never solve the issue. Thanks in advance for all your guys help.

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    Registered User Heide264's Avatar
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    Sorry if I missed it, but what mods have been done to the car and is it appropriately tuned?

    It may be a mechanical issue, but its still a pertinent consideration in my opinion.
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

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    Sorry for the late response. I was driving home and figured it out. The boost solenoid is bad. I unplugged it and sure enough pulls clean through 3rd and 4th with no hesitation or surge although its at 7 or so psi, but that is to be expected.

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    Registered User frenziedcage's Avatar
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    7psi? on stage 2? that doesn't sound right stage 2 you should be pushing at least 14 psi minimum over course there's room for more boost its what you're tuner thinks is safe. Is the car even tuned? you shouldn't be driving with a catless dp without a tune on wot.

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    Registered User frenziedcage's Avatar
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    of course* your*

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    Registered User Heide264's Avatar
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    Quote Originally Posted by frenziedcage View Post
    7psi? on stage 2? that doesn't sound right stage 2 you should be pushing at least 14 psi minimum over course there's room for more boost its what you're tuner thinks is safe. Is the car even tuned? you shouldn't be driving with a catless dp without a tune on wot.
    It's because he pulled the boost solenoid and is running waste gate spring pressure bud.
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

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    Registered User Heide264's Avatar
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    Quote Originally Posted by franchisco7 View Post
    Sorry for the late response. I was driving home and figured it out. The boost solenoid is bad. I unplugged it and sure enough pulls clean through 3rd and 4th with no hesitation or surge although its at 7 or so psi, but that is to be expected.
    It could be a bad solenoid, but keep in mind that the ecu controls the solenoid (obviously). Just inferring that it could be due to the tune as well judging off of that piece of troubleshooting.

    I guess if you don't mind... Replace the solenoid with a new one and see how it goes.
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

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    Yes I am running a catless dp without a tune. You have to remember for my car up until a certain point which is around 5k on my car ecu compensates for fuel adjustments using the forward o2 sensor. once it reaches that 5k or so limit is when it switches to open loop fueling. I am safe running a catless downpipe as long as I keep it under 5k or so which is what I do. I do plan on getting a tune soon. And Heide264 is right its only running 7psi because im on waste gate pressure. I will first check the all the lines going to the solenoid just to be sure that they are intact and all the connections are good. If they are I will get a new solenoid and that should fix the problem. Thanks all for the input.

  10. #9
    Registered User Heide264's Avatar
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    Is this an older model? I am familiar with how the car ecu works... But I have a feeling your logic is a good bit off.

    Edit, read above.

    Your car still won't remove the timing that should be removed with a better flowing down pipe. Until it detonates that is. Also, you'll need some serious boost control tweaks. Just since it has a forward o2 doesn't mean the car will magically fix itself. Fuel trims are a small part of the picture.
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

  11. #10
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    2002. I understand that without a tune it will not run to its full potential and I am getting a tune within the next month so it is not an issue. However it is still safe for 2002-2003 wrx and 2004-2006 sti cars to run a dp without a tune.

  12. #11
    Registered User Heide264's Avatar
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    Quote Originally Posted by franchisco7 View Post
    2002. I understand that without a tune it will not run to its full potential and I am getting a tune within the next month so it is not an issue. However it is still safe for 2002-2003 wrx and 2004-2006 sti cars to run a dp without a tune.
    Spoke my peace.

    Don't lope it over to the 04 stis for sure. I know first hand you will over boost like crazy. You'll also be knocking a good bit mid and high power band. Don't mind you having an opinion on your car, but I don't want to leave that info there for anybody else who reads the thread.
    Quote Originally Posted by Trainrex
    He was throwing balloons filled with sulfuric acid and shrapnel at the swat team. They finally had to take him down with rubber bullets.
    2011 STi Build Log
    -Part 1 - Reading, Data Logging, and Analyzing Data
    -Part 2 - Turbocharger 101 & Basic Boost Control
    -Part 3 - EcuFlash, Experimental Defintions, and a Drive By Wire Intro

  13. #12
    Admiral Ackbar the 1st mycologist's Avatar
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    Yeah, bugeyes will run a DP with no tune and no major issues. Not the most advisable, but they get away with it better than any other year.

    Regardless, for your car specifically and the symptoms, getting a cable to log it is the first best step. Log it, use that information to run down mech. issues, then flash a better map. You will be able to see what your boost looks like, what your ECU is telling your BCS it should look like, and what is going on with A/F in closed loop, and most importantly what is going on with timing and DAM. I would guess that your ECU is seeing detonation and pulling timing, or you have some leaks in the boost control system or a bad BCS (common). Removing your BCS from the system only shows that the wastegate spring is working correctly, not what is wrong.

    I think you can log your car with a cheap ebay vagcom cable or at least a tactrix 1.3, both of which are affordable. There is a sticky thread in the tuning forum that discusses how to log the car. With the 1.3 you should also be able to flash one of the stage II maps (some are free but need to be logged).

    Datalogging with Romraider:

    Free 93 octane stage II map - requires logging to check for knock. This will make a nice improvement and probably be safer than what you are doing at much nicer boost levels (16 psi is nothing).
    testes1010 OpenECU Maps, did I mention FREE?

    If you want to keep taking pot shots at it, check for any air leaks in the intake track - check all the clamps up to the turbo and make sure there is no tear in the turbo inlet coupling (can be on the bottom and very hard to check. Leaks between the MAF and the turbo let in unmetered air, lead to lean conditions, and cause detonation resulting in pulled timing, and possible damage.
    Last edited by mycologist; 08-11-2012 at 08:38 PM.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

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