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Thread: 2004 lb7 loss of power

  1. #1
    Join Date
    Jan 2005
    Posts
    15

    Question 2004 lb7 loss of power

    my lb7 has ben getting slugish off of stop signs and over the last few times i have driven it towing and with out a load. it has a new fuel filter and a clean air filter. it is even more noticeable when it is not at operating temp. sees like a 2000 rpm it will just sit there and not do any thing for a short time and the it stars to pick up rpm slowly.
    2004 CC D/A LB7 4X4 with edge juice with attitude, BD air filter system, 4in exhaust, 4" rancho lift, 315x75x16 tires, superlift speedo correction

    2004 Terry Quantum 300BH TT

    2004 CC D/A LLY 4X4 chassis to put my 72 suburban body on.

  2. #2
    Join Date
    Mar 2007
    Location
    Pacific Northwest
    Posts
    740

    Thumbs up

    First step is to disconnect the EDGE and see if the problem goes away. Second step is to verify the fuel and air filter. Third step would be to ramp up the fuel rail pressure and see if it can even make at least 145 Mpa. It should make 160 Mpa no problem! If unable to make 160 Mpa, probably has a bad set of fuel injectors.
    1998 Chevy k-2500 454 147,000 miles and climbing!

    1993 Pontiac G/A Big Block 3.3 Liter 140,000 miles and still going too!

  3. #3
    Join Date
    Jan 2005
    Posts
    15

    Default

    I have disconnected the edge and it still does the same. the air filter is new AFE no oil filter only 800miles on it. Fuel filter is only 800 miles on it. do i need to change it again? how do you change the fuel pressure? And what and where do i hook a pressure gauge up at?
    2004 CC D/A LB7 4X4 with edge juice with attitude, BD air filter system, 4in exhaust, 4" rancho lift, 315x75x16 tires, superlift speedo correction

    2004 Terry Quantum 300BH TT

    2004 CC D/A LLY 4X4 chassis to put my 72 suburban body on.

  4. #4
    Join Date
    Mar 2006
    Location
    Phoenix, AZ
    Posts
    144

    Default

    are you saying it does this when it is not warmed up?

    any codes?

    can you put the old intake back on?
    Michael 04.5 SRW LLY

    custom stock intake, upsized boost tubes, Pre-turbo WMI, EFILive custom tune, Aerotech Scan Gauges.

    Go Smokeless!

  5. #5
    Join Date
    Jan 2005
    Posts
    15

    Default

    all the bd intake is just the box no tubes. the bd with a K&N has been on the truck since new. I just changed the K&N out for a AEM dry flow filter. The sluggish feeling is even more noticeable when the truck is not up to aoperating temp but still there when it is warmed up
    2004 CC D/A LB7 4X4 with edge juice with attitude, BD air filter system, 4in exhaust, 4" rancho lift, 315x75x16 tires, superlift speedo correction

    2004 Terry Quantum 300BH TT

    2004 CC D/A LLY 4X4 chassis to put my 72 suburban body on.

  6. #6
    Join Date
    Mar 2006
    Location
    Phoenix, AZ
    Posts
    144

    Default

    I believe this is your problem.

    The ECM withholds fuel until sufficient airflow is sensed (MAF sensor). IOW, the fuel dosage must be matched by a charted air flow, or added fuel will not be scheduled. The oiled elements noriously "deaden" the hot wire type MAF sensors as oil and dirt accumulate on the wire over time. So the MAF sensor is relaying less MAF than before, causing sluggish throttle response.

    clean your MAF sensor with alcohol and compressed air.

    Also, check for codes. Probably none, but always check. If the attitude shows MAF, you can do a before/after comp.
    Michael 04.5 SRW LLY

    custom stock intake, upsized boost tubes, Pre-turbo WMI, EFILive custom tune, Aerotech Scan Gauges.

    Go Smokeless!

  7. #7
    Join Date
    Jan 2005
    Posts
    15

    Default

    I cleaned the MAF sensor. still runs the same changed the from the new dry flow filter to the old K&N filter still acts the same. acts slugish with the edge juice connected and disconnted.

    What next.
    2004 CC D/A LB7 4X4 with edge juice with attitude, BD air filter system, 4in exhaust, 4" rancho lift, 315x75x16 tires, superlift speedo correction

    2004 Terry Quantum 300BH TT

    2004 CC D/A LLY 4X4 chassis to put my 72 suburban body on.

  8. #8
    Join Date
    Mar 2006
    Location
    Phoenix, AZ
    Posts
    144

    Default

    Is this with the stock intake box now?
    What codes did you have?
    Michael 04.5 SRW LLY

    custom stock intake, upsized boost tubes, Pre-turbo WMI, EFILive custom tune, Aerotech Scan Gauges.

    Go Smokeless!

  9. #9
    Join Date
    Jan 2005
    Posts
    15

    Default

    I do not have a stock box. it has factory tubes to a open round filter. had a K&n filter until 800 miles ago when i changed to a AEM dry flow oilless filter. As stated before the box has been on the tuck for most of its life. the truck run the same with the K&N or the AEM dry flow filter. has the same slugish felling with the edge juice and with out. here is a link to the bd air box pictures.

    http://www.bd-power.com/gmc/gmcxtream.html
    2004 CC D/A LB7 4X4 with edge juice with attitude, BD air filter system, 4in exhaust, 4" rancho lift, 315x75x16 tires, superlift speedo correction

    2004 Terry Quantum 300BH TT

    2004 CC D/A LLY 4X4 chassis to put my 72 suburban body on.

  10. #10
    Join Date
    Mar 2006
    Location
    Phoenix, AZ
    Posts
    144

    Default

    Quote Originally Posted by killerbee
    What codes did you have?

    ..........
    Michael 04.5 SRW LLY

    custom stock intake, upsized boost tubes, Pre-turbo WMI, EFILive custom tune, Aerotech Scan Gauges.

    Go Smokeless!

  11. #11
    Join Date
    Jan 2005
    Posts
    15

    Default

    i dont have a ses light on. i do not have a scanner to see if there are any iother codes.
    2004 CC D/A LB7 4X4 with edge juice with attitude, BD air filter system, 4in exhaust, 4" rancho lift, 315x75x16 tires, superlift speedo correction

    2004 Terry Quantum 300BH TT

    2004 CC D/A LLY 4X4 chassis to put my 72 suburban body on.

  12. #12
    Join Date
    Mar 2006
    Location
    Phoenix, AZ
    Posts
    144

    Default

    autozone will scan for free. There are many codes that don't trigger SES.
    Michael 04.5 SRW LLY

    custom stock intake, upsized boost tubes, Pre-turbo WMI, EFILive custom tune, Aerotech Scan Gauges.

    Go Smokeless!

  13. #13
    Join Date
    Jan 2020
    Location
    Nevada
    Posts
    3

    Default Same problem

    Same issue with lb7 here. Have been throwing parts at it but no change. Did you ever find the issue. I found found a couple similar post but nobody seems to put the final result and fix. Any help would be appreciated.

  14. #14
    Join Date
    Mar 2000
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    Loyal WI US
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    10,792

    Default

    Quote Originally Posted by Jm1205 View Post
    Same issue with lb7 here. Have been throwing parts at it but no change. Did you ever find the issue. I found found a couple similar post but nobody seems to put the final result and fix. Any help would be appreciated.
    Air and fuel are the keys. What if any work has been done recently prior to the start of the issue? Particularly have the injector lines been loosened/removed?
    Kennedy Diesel-owner
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