Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Mods completed, poor performace issues!!!! HELP!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ftn96, Mar 18, 2002.

  1. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Ok cutting to the chase here: Just completed this mod list:
    1. Thorley headers(strock CAT, no mufflers straight pipe all the way back),
    2. PVC valve,
    3. spark plugs-(gapped 35),
    4. TCI Street Fighter Transmission,
    5. TCI Rv/Tow Torque Convertor,
    6. New gas tank,
    7. rebuilt T-case...

    List of performacne issues at hand:

    1. Lack of take off power (less than before mods list)
    2. Wont downshift for "passing gear" use.<font color=red>(Even if I mash it to the FLOOR!!!)</font color=red>
    3. Shudders once the Torque convertor locks in at lower speeds
    4. Hesitant while accelerating (<font color=red> Jumps back and forth between running good and bad in a split second,</font color=red>)
    5. Sounds like fuel pump is making a loud buzzing noise
    6. And randomly it sorta stumbles <font color=red>(falls on its face) at stop light while idling and under acceleration)</font color=red>

    I have adjusted the TV cable, First one Ive done so Correct? I dont know. Could the EGR valve be causing some of this lack of power stuff?

    I need you all to dig deep here.
    Thanks in advance. I'll check replies in the morning!
     
  2. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    sounds like you might contribute #'s 1,4,5,&amp; 6 all to the fuel pump... from my experience, loud pumps are failing pumps. But I could be wrong of course... did you replace the pump when you replaced the tank? As for 2 &amp; 3, I would contact TCI and see what they suggest. Just my .02
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,555
    Likes Received:
    156
    Location:
    Cochrane, Alberta, Canada
    I have a couple of comments:

    1. Did you upgrade your exhaust pipes when you did the headers? If you went too big with your exhaust it can cause poor low end power.

    2. Have you swapped out your fuel filter since you changed the gas tank out? Maybe there was some crud in the new tank that plugged your filter. A lot of your probelms sound fuel related.

    3. Is there a chance that your wires need replacing? If they are worn out the extra heat from the headers may be causing your wires to overheat and cause performance issues.

    Just a couple of things to think about.
     
  4. fortcollinsram

    fortcollinsram 1/2 ton status

    Joined:
    Nov 8, 2001
    Posts:
    2,261
    Likes Received:
    0
    Location:
    Fort Collins, CO
    How did you adjust the TV cable? There are several methods and I feels some are more acurate than others...The fact that your tranny won't down shift sounds like the TV cable is too loose...

    Chris
     
  5. 87GMCJimmy

    87GMCJimmy 1/2 ton status

    Joined:
    Nov 21, 2001
    Posts:
    582
    Likes Received:
    0
    Location:
    Phoenix, AZ
    One problem I had when I first installed headers is that I left one off the sprak plug wires barley touching a header and it burnred through and was shorting. Hitting bumps would bounce the wiring on and off intermittently.

    Check fuel pressure as mentioned about, but I don't thing that would cause a problem at idle.

    O'wait, did you install a heated o2 sensor? The truck will run crappy at idle and cruise unless you really romp the motor for a couple of minutes to heat up the headers enough to make the o2 sensor work properly. A good indicator for this is when you first start the truck it will idle fine (the computer is in open loop mode and not using the o2 sensor input). Then after a minute or two the idle start to miss and be crappy ( the computer is now in closed loop using o2 sensor input which it no good because it is not hot enough to give a correct reading)


    Some things to check
    Later
    Mike
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,188
    Likes Received:
    1,396
    Location:
    E-town baby!
    I'd still check the EGR and consider going back to a stock convertor. My two cents...

    rene
     
  7. jimmy88

    jimmy88 1/2 ton status

    Joined:
    Feb 17, 2002
    Posts:
    351
    Likes Received:
    0
    Location:
    Detroit, MI area
    Sounds like you got a few things going on. Items 2 &amp; 3 sound like the TV cable adjustment. I rebuilt my 700r4 with the TCI kit and have the TCI towing TC, 4.56, 33's, the stock tired 350 TBI and the truck launches and shifts good. Call the TCI tech number in the paper work that came with your trans, the guy I talked to a couple years ago seemed to know his stuff.
     
  8. TrcksR4ME

    TrcksR4ME 1/2 ton status

    Joined:
    Feb 11, 2002
    Posts:
    2,482
    Likes Received:
    0
    Location:
    Seattle, WA 98103
    So you are running with no mufflers? I have heard many times that you need the back pressure from the mufflers for off-the-line power. That could be part of the problem, but sounds like there are more issues. Definately check the fuel pump, that can really cause problems with performance.
     
  9. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    1st off I called TCI for help with characteristics and they said TV out of adjustment but not really sounding to enthused about helping with the actual adjustment. I did the push the tab in, slide the sleeve back all the way against the bracket and opened the throttle assembly all the way open.
    2. I kept all stock pipes with the header install.
    3. Heated O2 sensor? What the hell is that? Never heard that one before. I re-installed the existing O2.
    4. Rene, I might be going to a different convertor but I will make that decision when I know everything else is correct and then I'll decided if I want to change it. As far as the EGR goes. Im gonna replace it. Since its not that $$ anyway.
    5. No mufflers. Same as before.

    Now that I have basically answered all the ?'s. I'd like to summerize....

    I feel that it has a fule delivery problem. Mainly due to the fact that it should run at least somewhere in the same ball park as it did before. But it has nowhere near the same amount of power. I can stop at the bottom of the driveway and floor it and it wont wind up till towards the top, then it starts to sputter and then run good then back to crap again.
    2. I know the TV cable is not correct but, now I've heard 2 different things as far as adjusting it. #1 if it aint downshifting it sounds like its too loose. I also heard the opposite. When it shifts from 1st to 2nd with the pedal mashed it will "SNAP" your freaking neck in half. But Im not getting the half and full throttle downshift which is my main concern. Actually my main concern is not having it right and burning up the tranny.

    Next issue is that its hard to properly adjust the tranny if the motor isnt running right so I need to start with the other issues at hand first dont I?
    So shouls I replace the EGR and try it, then on to the fuel pump? Also remember the fuel pump is the stock one and since I 've put the tank back in it is making a loud buzzing noise.
     
  10. 87GMCJimmy

    87GMCJimmy 1/2 ton status

    Joined:
    Nov 21, 2001
    Posts:
    582
    Likes Received:
    0
    Location:
    Phoenix, AZ
    I almost be willing to bet the o2 sensor is your running problems, go get a generic 3 wire o2 sensor and install it. I went though the same thing when I installed my headers. The o2 sensor will cause a lean fuel mixure and thus the fuel delivery problems. If you have a scanner hook it up and look and the o2 voltage.

    later
    Mike
     
  11. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Ceramic 3 wire? where or what might I find one of those off of? and where do the other 2 wires hook up?
     
  12. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Also, could I just unplug the O2 and see if it runs any better? Or would this be an open loop sorta thing where it wouldn't help for troubleshooting?
     
  13. 87GMCJimmy

    87GMCJimmy 1/2 ton status

    Joined:
    Nov 21, 2001
    Posts:
    582
    Likes Received:
    0
    Location:
    Phoenix, AZ
    This is the one I got.

    http://www.automedicsupply.com/walkeruniv.html

    The other wires are power and ground. These heat the o2 sensor so it never cools off. Just connect power wire to an ignition switched power source.

    I'm not sure what unplugging the o2 sensor would do.

    Mike
     
  14. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Talked to Thorleys tech and he stresses a stock replacement type with a new fuel filter. So I got those and a new fuel pump.
     
  15. 87GMCJimmy

    87GMCJimmy 1/2 ton status

    Joined:
    Nov 21, 2001
    Posts:
    582
    Likes Received:
    0
    Location:
    Phoenix, AZ
    Before I spent the money I would use a scanner and look at the o2 voltage readings. Or, you could just temporarily wire in an el-cheapo voltage meter to the one wire o2 sensor and to ground. The signal should be pretty actively bouncing around from .3 to .7 volts if I remeber right. If it ran find before the headers and not well after while using the same o2 senser, I would have a hard time believing the the o2 sensor suddenly went bad.

    A heated o2 sensor is a very common mod with headers.

    Good luck!
    Mike
     
  16. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    EGR valve is relateively easy to test, at least that component..any switches or anything that are causing problems related to the EGR could be suspect too.

    While idling, reach under the EGR valve and push the diaphram up. If you can do this, and it dies or stumbles, then you know that its pretty much ok.

    I wouldn't be blaming the EGR though, cruise is the only time it is used, not idle, nor WOT.

    I've seen "bad" EGR's cause idle stumble and stalling on deceleration. In this particular case, the "bad" EGR just had a lot of carbon built up, and it wasn't moving freely. A little cleaning and good as new. Apparently the EGR passages can be prone to clogging as well, so if messing with EGR, something to watch for as well. Again, I'd stay away from the EGR as a culprit right now.
     
  17. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Well, at $62 bones a pop. I'm gonna wait on the EGR till after the new O2, fuel pump, and fuel filter are swapped out. If they dont fix it then I'll check into the EGR. IT very well, could be the TV cable being way out of adjustment that is causing some problems, but I just can relate the 2 at this time.
     
  18. 86blazerk5

    86blazerk5 1/2 ton status

    Joined:
    Aug 9, 2000
    Posts:
    387
    Likes Received:
    0
    Location:
    Hagarstown, Maryland
    I can only really help on one thing and that is that one thing i know for sure from a budyys 87 K5 is that a noisy humming fuel pump is a bad fuel pump. But I see you have already bought an new one and once it is installed, i bet it will run way better, but that isnt nessisarly going to fix all your problems.
    Ike
     
  19. zakk

    zakk 1/2 ton status

    Joined:
    Sep 21, 2001
    Posts:
    4,762
    Likes Received:
    0
    Location:
    San Jose CA
    total guess, but i had stumbling problems when my distributor when. might be a contributing factor.
     
  20. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Well, Hopefully I can get that installed tonight. And a new O2 wont hurt nothing. Im just trying to decide whether or not to cut an access whole in the top of the bed pan to ease the pump swap or just drop the tank again. Probably outta just drop the tank. /forums/images/icons/frown.gif
    It doesn't have much gas in it anyhow.
     

Share This Page