Results 1 to 9 of 9

Thread: My first CEL...P1088 TGV Sensor

  1. #1

    Exclamation My first CEL...P1088 TGV Sensor

    Well, my 02 WRX is over 140k (HARD) miles so a CEL is expected at some time.

    Here’s the car symptoms and lead-up…last week got in the car to drive to work and noticed a bit more ‘airy’ noise coming from the engine bay (apart from the usual turbo/blow-off noise). Also had lower acceleration, engine power, and lower peak boost levels (only 2 or 3 psi lower). There was no stuttering, surging, knocking or pinging. Idle was fairly normal. Thought it was maybe an intake or exhaust leak. Figured it was something minor so I kept driving it in this condition.

    Well the CEL tripped yesterday, which is nice because it allows me pinpoint the problem. Took it by Subaru and they scanned and….

    P1088-Tumble Generator Valve #1 (RH) Position Sensor Circuit Low Input

    This could be a number of problems. It may be simply a faulty electrical connection or bad sensor. Or it could be mechanical. The TGV valve is normally closed at idle and idling feels all right. When I gas it is when I can tell something is not operating correctly. Could the valve be stuck in the closed position? Or maybe the motor that actuates the valve shaft is not operating? If the valve is stuck in the closed position then it's probably the source of the ‘airy’ noise I’ve been hearing because the air is being forced through the small bypass port. I know the sensor sends a signal to the ECU so does the valve motor actuate based on this signal. Like if the sensor can't send the proper singal to the ECU then the ECU doesn;t send the right singal to the motor and the valves don't operate?

    I’m going to do a full diagnostic this weekend to check voltages, resistances, and connections. It looks like I can do the diagnostic without removing anything. Hopefully it’s just a dirty/loose connection. Subaru says that if the sensor is bad then the whole sensor/valve assembly will need to be replaced (instead of just replacing the sensor). Is that correct?

    I know that replacing the TGV will require removal of intake manifold, which I’ve been wanting to do for a while now to fix my leaky soft fuel lines. Looks like coolant and gaskets will be all I need for this IM/TGV removal and replacement.

    So…Subaru wants around $260 for one TGV and I found some aftermarket pair of TGV deletes for under $200. PROS…I am in a county that doesn’t require emissions, it looks like it would be cheaper to buy this aftermarket part than buying the OEM replacement, more POWER!!! CONS…ECU tune looks like its needed??? I have an old ChipTorque Exceed ECM controller out of Australia and I don’t know if I can get a new map easily. Can I do this delete myself? I.E. removing the Butterfly valves so it’s just open all the time? I don’t really care if a CEL is on all the time, I just want my performance back. But having a CEL on all the time will not alert me to other CEL trips. That’s OK-ish.. I can feel the engine performance and know if something else is wrong.

    One major question…how long can I drive like this until I cause other problems? I’m taking it easy on her for the most part.

    PLEASE COMMENT!!!

    "I'm a Professional Engineer, a Semi-Professional Race-Car Driver, and an Amateur Rock Collector."
    ol' Blue Betty -> http://www.dirtyimpreza.com/forums/v...p?do=view&g=68
    Silver Lining -> http://www.dirtyimpreza.com/forums/v...?do=view&g=453
    Everything Else -> http://about.me/CollinsAE


  2. Don't like seeing these ads? Register on the DirtyImpreza.com forums today - Click Here
  3. #2
    Senior Dirty Member
    Join Date
    Dec 2007
    Location
    mn
    Posts
    2,070

    Default

    delete the TGVs, use enginuity (open source tuning - free, all you need is a tactrix cable) to turn off the CEL

  4. #3

    Default

    You can take apart the intake manifold and simply remove the plates off the TGVs therefore eliminating them and the ECU still thinks they're working, but this will not fix your problem if it actually is the solenoid/motor. You should be able to find just the motor for cheap though as a lot of people eliminate them.

    Simple little trick if you think they're sticking, which makes sense considering the mileage.

    -Kurt

  5. #4

    Default

    The ECU will not need tuned. The stock ECU will work fine, but you need to have some way of deleting the TGV codes (after delete) otherwise your ECU will go into limp mode.

    So after a delete, you can drive a little.. but delete the codes ASAP.
    2006/2008 - Western Ohio Region SCCA M4 Champion
    2007 - Ohio Valley Region M4 SCCA Champion, 2nd in M4 Western Ohio Region
    2008 - Great Lakes Division M4 Champion
    2009 - ESC 3rd place M4

    Matthew Noble Marker= - You will not be forgotten. Rally on.

  6. #5

    Default

    Thanks everyone. I'm going to do an electircal diagnostic this weekend to try and find/fix the electrical connection if it is that. If I do the TGV delete that won't really solve the faulty electrical code, but it will give me my airflow back. How much damage will I do if the p1088 code is permanently tripped? What does a limp mode do? The subie dealer said as long as the CEL isn't flashing then I'm OK-ish. Is the CEL flashing mean 'limp mode'?

    I read on another forum that the flow divider plate is a bump stop for the valves. If I remove the valves but leave the rod/motor in place will the motor try and spin forever? Maybe if I just disconnect the power supply to the motor it will solve this potential problem?

    It looks like the TGV sensor is the same part number as a throttle position sensor, so if it is a bad TGV sensor I CAN replace jsut the sensor.

    Found a used sensor/motor at Grimmspeed for $40.

    ALSO very important question...Is the RH side the passenger side or the drivers side?
    Last edited by enginerd; 11-13-2009 at 04:40 PM.

    "I'm a Professional Engineer, a Semi-Professional Race-Car Driver, and an Amateur Rock Collector."
    ol' Blue Betty -> http://www.dirtyimpreza.com/forums/v...p?do=view&g=68
    Silver Lining -> http://www.dirtyimpreza.com/forums/v...?do=view&g=453
    Everything Else -> http://about.me/CollinsAE

  7. #6

    Default

    After the weekend of testing and thinking...

    RH side of Engine is Passneger side and the sensor is back by the Turbo. The sensor is literally an inch from the intake turbine housing! I bet the heat isn't so good on it. I also replaced the Turbo last fall so maybe bumping it caused the damage.

    Anyways figured out how to remove the sensor while only removing the turbo heat shield. I had to thread a 3/8" x 6" socket, elbow, and 7mm socket in between the turbo and a mounting bracket to get at the bottom screw. Inspected connections and reinstalled and no change to car. I ordered a used sensor/motor from GrimmSpeed and will isntall that one when it comes. Still driving car for now. If the sensor repalcement doesn't work I'll do a full TGV delete and Tune the CEL's out.

    I've read at a few other random websites that the TGV Position Sensor is 'pre-loaded' onto the TGV housing (i.e. you put it on the valve shaft and rotate it 90 degrees clockwise then screw it down) http://www.scoobymods.com/tgv_sensor...60.html?t=5160 Anyone have better information on that? The TGV Sensor is identical looking and seems to provide the same voltage output as the Throttle Position Sensor. They basically do the same thing. I tried to look in the Subie Manual for the TPS isntallation instructions and it just says install it and doesn't say anything about the pre-loading it. Both the TPS Sensor and the TGV Sensor meaure a 90 degree turn of the valve, right?

    I'm really trying to figure this out...Does the TGV Actuator Motor operate directly from the the Postion Sensor signal (i.e. if the sensor is bad the motor doesn't operate), or is the Postion Sensor just a 'check' and limits motor power/boost levels for safety reasons just in case the motor isn't operating? Is there a specific CEL for bad TGV motor?
    Last edited by enginerd; 11-16-2009 at 03:23 PM.

    "I'm a Professional Engineer, a Semi-Professional Race-Car Driver, and an Amateur Rock Collector."
    ol' Blue Betty -> http://www.dirtyimpreza.com/forums/v...p?do=view&g=68
    Silver Lining -> http://www.dirtyimpreza.com/forums/v...?do=view&g=453
    Everything Else -> http://about.me/CollinsAE

  8. #7

    Default

    So I guess I'm just talking to myself some more. Really just completing the story so that anyone in the future that has this problem can find this thread and hopefully learn from it.

    MY CAR: 2002 Impreza WRX Wagon, 140k miles, light mods

    PROBLEM: CEL P1088 Tumble Generator Valve (RH) Postion Sensor Circuit Low Voltage, caused car to drive poorly, loss in power and boost and low acceleration

    Tried remove and re-install exsiting sensor and clean connections. Ended up re-mounting the sensor incorrectly (see below) which caused the car to drive even worse. Very rough/noisy engine noise above 3,500 rpm, boost very low and boost guage needle shaking above 0 psi.

    FIX: Purcahsed used sensor motor kit from GrimmSpeed.com for $50 (inlcuding shipping). Kit actually included two sensors and two motors. Pretty good deal. Other more expensive solutions inlcude buying new Throttle Position Sensor (same part as TV sensor) from Subaru for around $90. OR buy entire TGV housign and sensor assmebly from Subaru (that was there recomended solution) for aroun $270, which would;ve invovled taking off the intake manifold.

    Had to remove two bracekt bolts and loosen the intake tube to turbo c-clamp in order to be able to rotate the sensor 90 degrees. Yes the sensor is pre-loaded. You have to put it on at noon to 10 o'clock and then rotate clockwise to 3 o'clock, then screw her down. Getting to all of the sensor screws required a 1/4" x 6" extension w/ 7mm socket and wobble elbow. Really tough to get at these screws. Getting to the two mounting bracket bolts required a 12mm box wrench and many MANY small turns. removed intake filter as well to be able to get into the area.

    Got it all done in about an hour. Dropped screws and sensors many times. Thank god for my little magnetic pointer thingy. Drove her around the block and was driving great, so ran some errands and on the 5th time starting my car after the repair, BING the CEL went off!! SAWEETAH.
    Last edited by enginerd; 12-02-2009 at 03:47 PM.

    "I'm a Professional Engineer, a Semi-Professional Race-Car Driver, and an Amateur Rock Collector."
    ol' Blue Betty -> http://www.dirtyimpreza.com/forums/v...p?do=view&g=68
    Silver Lining -> http://www.dirtyimpreza.com/forums/v...?do=view&g=453
    Everything Else -> http://about.me/CollinsAE

  9. #8
    Regular Contributor SilverSleeper04's Avatar
    Join Date
    May 2009
    Location
    Fort Collins, CO
    Posts
    493

    Default

    Quote Originally Posted by enginerd View Post
    So I guess I'm just talking to myself some more.
    haha well i'm glad you did. so a few weeks ago i got the same code. except it's 1086. so mine is the LH or driver's side with the position sensor circuit low voltage. i'm going to have to go check out grimmspeed and see if they have any used ones. one thing tho is that i'm not experiencing any drivability problems. i don't have any performance problems whatsoever....lucky me i guess.

  10. #9
    Regular Contributor SilverSleeper04's Avatar
    Join Date
    May 2009
    Location
    Fort Collins, CO
    Posts
    493

    Default

    picked up a set of used sensor and actuators from grimmspeed for 45 dollas. put the new err used position sensor on and the cel didn't come on the 4th time i drove the car.

    edit: oh ya and subaru quoted me at $850+ for parts and labor to have them fix it because you can't just get the position sensor by itself. $45 or $850......man am i glad i know how to work on cars


  11. Don't like seeing these ads? Register on the DirtyImpreza.com forums today - Click Here

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •