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  1. #1

    Default 97 k3500 5.7l power dilemma. HELP!!!

    So i have a 97 k3500 5.7l, we bought it for towing our holiday trailer and from the first time i towed it seemed to be lacking power. (I will try and give as much info as i can to make it easier for everyone). Before i even hooked up to the trailer a friend convinced me to have the computer reprogramed for better milage and more power, so i did. Could not relay feel a difference around town, then we hooked up our trailer (4100lb dry and 7500lb loaded) for the first time and man was it ever gutless. I had more power with my dads 02 5.3l and my old 90 k1500 5.0l. The truck drank fuel and had zero power when we got to some bigger hills, on the flat and small inclines was tolerable but anything bigger or a head wind, it was junk. The truck sports a 5.7l with about 150000km (sorry dont know what it is in Miles), 4L80e trans, 4.10 gears, HD frame, air bags in the rear for extra help, 3 trans coolers (1 good for 28000 lbs), k&n air filter with the top of the air box removed for more flow, both of the cats have been gutted and no check engine light. I have changed the plugs, fuel filter, cap, roter, pcv valve and cleaned the air filter, can some sea foam throught a couple tanks of gas and one can was sucked through a vacuum line, engine shut off and then started again 25 mins later to clean up any carbon. Compression tested 180psi on 7 out of 8 clys and 185 on the other. The problem is almost non existent with no trailer, but still at highway speeds seems a bit lacking.

    Other thinks i have tried...
    -Towing the trailer with it unplugged thinking it was the breaks hanging up. Problem still there
    -Driving in a lower gear to keep the RPM's up. Still there
    -Tried with everything shut off, A/C, fan, radio, etc. Still there.

    It is getting a bit frustrating. We are going to the Oregon coats for 2 weeks in Aug and i want to figure this problem out before then so i can enjoy the drive and my vacation. I realize that this is not a Diesel or a 454, but like i said before i used to have an old 90 5.0l and towed a 6000lb race car trailer every weekend with no issues.

    Can anyone help my out or give me some pointers or suggestions.

    Thanks in advance and sorry for the long post.

    Steve

  2. #2
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    stephan's Avatar
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    I'm guessing that when they reprogrammed the computer they favored the MPG & this has hurt your power.
    Since you suspected the trailer brakes hanging & disconnected the electrical to test, I'd go another step & jack up the trailer & spin the wheels. They could be dragging from mechanical issues rather than a bad electrical controller.
    You have good compression on your 5.7 L & with 4:10 gears should pull 7500 lbs fairly decent. Mine dogs out on really steep hills pulling my boat & trailer also 7500 lbs. (down to 40-45 mph) but not unusual for this amount of weight imo.
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  3. #3
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    Alright well i will start off with a couple of questions.. please dont take an offense. What type of plugs did you put into the motor? And i agree with Stephan that they went the wrong way with the tune, and have you running for better milage which is killing your towing ability. Do you still have a muffler installed? Because a lack of back pressure from the gutted cats (if you dont have a muffler) you wont have the power that you need.
    Also i agree to take a look and make sure there isnt anything dragging on the trailer axles. And with "roughly" 92K miles that motor is like brand new for the most part.
    Mike

    Currently

    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

  4. #4

    Default

    Thanks Stepan and Murdog for your quick replys.

    I have not checked the drag on the trailer, but i am guessing because i recently used my dads truck to move the trailer and had no problems. As for the plugs i have NGK plugs from NAPA. I just told them the truck and they said these are the ones. I do have a muffler on the truck. Would it be worth it to buy a programer with multiple setting on it, tow/millage/performance/etc? I am going to check fuel pressure this week but i think it is ok as the truck is not bad with no load. I was also leaning towards the computer being too lean for milage.

  5. #5
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    The plugs are the wrong ones for the motor, and actually NGKs are about the worst ones to run (other than those stupid E3 things) that can cause a loss of power... Running AC delco Platinums is a good idea since the NGKs might last 4K miles but start to screw up and then you are stranded.
    Now for the programmer yes it would be a much better idea to get a good multiprogram programmer. Alot of shops that do "custom tuning" dont necessarly do the best job of it.

  6. #6

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    Quote Originally Posted by murdog94 View Post
    The plugs are the wrong ones for the motor, and actually NGKs are about the worst ones to run (other than those stupid E3 things) that can cause a loss of power... Running AC delco Platinums is a good idea since the NGKs might last 4K miles but start to screw up and then you are stranded.
    Now for the programmer yes it would be a much better idea to get a good multiprogram programmer. Alot of shops that do "custom tuning" dont necessarly do the best job of it.
    X2....On the NGK's being the Wrong Plugs and also as mentioned by Murdog94....you want A/C Delco Platinum Plugs....the Vortec Engine's Run & Perform Best When A/C Plugs are being installed.

    MIKE


    99"SILVERADO
    5.3 l 3.73 l G80
    BLACK BEAR CUSTOM TUNE
    SNUGTOP l COLORMATCH l KATZKIN










  7. #7

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    I will get some new plugs first thing monday, will old plug wires do the same thing?

    As for the programer which one is recommended? I am looking for more towing than anything.

    Steve

  8. #8
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    Old wires can cause a misfire.... As to a programmer if you search the site some you will see what others have used and what they prefer...

  9. #9

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    On the A/C Delco Plugs are Gaped during Manufacturing, which for the Platinum Plugs is set at....0.60, Check the Gap to make sure they are Gaped Correctly, but Do Not Attempt to re-gap them as the Platinum Tips Can be Easily Damaged.



    SPARK PLUG ASM

    Part Number: 41-993
    Product Notes:

    Platinum Spark Plug

    .060 GAP

    Per Vehicle: 8; Years: 1996-1998

  10. #10

    Default

    Don't forget to check the air intake tubing for restrictions. I've seen birds and mice build some pretty impressive nests in them and cause all kinds of problems. It's easy to overlook. Be sure to take it loose at all the connections so you can clear out the entire thing. By the way, I second the opinions on AC plugs.
    Good Luck and God Bless

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