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what does your truck idle @?

Discussion in 'The Garage' started by Avery4jc, Apr 27, 2007.

  1. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

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    I've had so much done to my truck lately its hard to tell what is affecting what...

    After it threw those codes (41 and 42) I took it in and they took care of everything...new plugs, wires, distributor, O2 sensor and a tune up.
    Now that I got it back I've been having this weird problem...

    When I'm sitting there in gear but with my foot on the brake (like at stoplights) every once in a while it'll feel like something engages, the truck doesn't roll forward but you feel it shift a little (exactly like when when you put it in gear from park)....so that has been weird and I can't figure out what it is...

    Then today when I was going through the drive-thru it was taking a loooong time and it was idling the entire time...after about 10 minutes it shut off....I popped it back in park and it fired right back up so I just cleared it out and it was fine....

    Here is my question...what is your idle @ when you are in gear just sitting there w/ your foot on the brake? Mine used to be at 500 and I never had any problems with this "jerking" or with shutting down...now its at 350-400...which I guess is enough of a difference to have issues...so is 350-400 too low?
     
  2. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    The jerking that you're feeling is probebly the stall saver coming in because your idle is way low. Idle is adjusted by the ecu to suit coolant temp, load etc. I think mine idles at 500 or 550 in gear all warmed up. 350-400 is too low. Even with the idle screw to far out the ecu should keep it at a preset value. Maybe they've messed with it and didn't set min air? Try doing that first and see how it goes(assuming everything else is good...no air leaks etc)
     
  3. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

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    I've got the stock carb....is the idle screw on the front left (when looking @ the engine)? I've adjusted it on my dad's 390 but never on mine...

    Oh and how do you set min air and what is it?
     
  4. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Hmmm...didn't realise you ran a carb, I only know how to do the TBI stuff. I think DYeager has some experience with ccc, maybe he'll chime in or you could PM him.
     
  5. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

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    yeah its no biggie I just wanted to make sure you guys thought there was a correlation between my low idle and the "engaging" and "disengaging" feelings that I was getting...
    I'll run it back by the shop and have them fix it b/c I'm afraid that if I do they won't want to touch it and will say its something I did.
     
  6. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Good idea. Hope they sort it for you. Let us know what happens.
     
  7. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Anything under 600 is WAY too low in gear.... Most specs are around 650 in gear...
     
  8. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

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    oh well then yeah its really too low...like I said I'm at about 350-400 in gear with my foot on the brake and its having a hard time staying alive...
    Tomorrow morning I'll run it back by the shop. I was going to go anyways b/c he said to bring it back saturday morning and he is going to help me fix some of my wiring going to my fuse box. He ran a new wire for the choke (that was messed up) but didn't have time to fix the other problems (they weren't related to what I had it in there for anyways) so he said he'll help me out if I come back tomorrow.
     
  9. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Was your AC on?
     
  10. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    not everyone lives in an ice cube like you Can Man, even I've used AC this year!:D
     
  11. vortec

    vortec 1/2 ton status

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    mine hunts and surges like that. used to be worse and idled around 500. after playing with the dizzy, it's now around 700 and idles a bit smoother. still think i probably need to mess with the idle screws, though.

    yours drives ok once you give it some skinny pedal? mine does.
     
  12. lochenjons

    lochenjons 1/2 ton status

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    Mine kinda of did this and I jsut messed with the air adjustment screws and it runs way better now. At the base of the carb are two screws one on the left and one on the right both on the front of the carb facing you. Start the truck and turn one of them in untill it stops or it dies. Count how many times you turned it in. Turn it out two times. Do the same on the other screw. If the times you counted turning it in was off that was probably the problem. Look in one of those manual books or search and youll find a better explanation but what I described worked for me. My truck was idling way low too, dont have a tach but it was low and now its fine
     
  13. 79k20350

    79k20350 3/4 ton status

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    That sounds like a vacum leak...
     
  14. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

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    paul: nope no a/c for me...I wish but it doesn't work. I have the blower motor working now but it only works in 1,2 & 3 and I only use it in the spring time to get fresh air, now that its starting to get hot I just leave it off all together.

    vortec: yeah it runs perfectly fine once I give it a little bit of gas...an increase of 100 or so rpm (up to the 500 range) and its good to go.
     
  15. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

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    I ran it back by the shop that did the 02 sensor, plugs, wires and distributor last week b/c he said that he wanted to help fix some of my wiring that I had going from my accessories to my fuse box. I have been using a couple spots on the bottom of the box b/c I tested them with a light and found which ones were wired in w/ the ignition but he said that in doing that I'm pulling power from other spots...such as my choke.
    So I went by and before he started to do the wiring I mentioned how when I have my foot on the brake and its in gear it just doesn't seem right...it surges a little (100-150rpm) and feels like it wants to die (and it did the other day in that drive-thru line)...
    So he climbed in and started checking it out only to find that I have developed a miss-fire again.
    He said that it looks like it might be one of the new plug wires but they only work a 1/2 day today so I'm going to drop it off monday before I go to school and he said he'll take care of everything.

    So I'll keep you all posted :)
     
  16. vortec

    vortec 1/2 ton status

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    yeah, i've been looking for one. can't seem to find it. it's unlikely that it's around the manifold, considering i installed just before i installed the engine, and that was only about a year ago. i'm not saying i can't make a mistake installing an intake manifold, but i never have before (edit: i've never made a mistake at it). what i'd like to do is remove all vac lines that aren't essential for the function of the engine and plug up the ports on the carb/manifold/etc. so that there are less places for a leak to develop and it would be a lot cleaner underhood.
     
    Last edited: May 1, 2007
  17. Avery4jc

    Avery4jc 1 ton status Premium Member GMOTM Winner

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    My truck died on me again today...he replaced the plug wire that was bad but he said that upon further inspection its nothing more than the carb...its the original carb and although nothing is specifically broken on it its just "worn out".
    But for the time being how can I turn the idle up on it? Its idling at about 450 and it keeps wanting to die. When I get it up to about 600-700 its perfectly fine so even if its just masking a problem it'll work for the time being until I can get a new carb...
    So yeah...thanks! Its a stock carb on an '85.
     
  18. 01maroonz71

    01maroonz71 1/2 ton status

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    my silver bullet idles at like 750 in gear, it's so high so that my a/c doesn't kill it when i switch it on, and with my cam, it has to be so high.
     
  19. lochenjons

    lochenjons 1/2 ton status

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    I dont know if its been mentioned already but I'd check the pcv valve. My truck did the same thing, bad idle, dying, etc. Ended up just being the pcv valve, $6 or so and my truck was like brand new. If it is the carb a rebuild is probably in order
     
  20. dyeager535

    dyeager535 1 ton status Premium Member

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    You can try increasing the idle by using the idle set screw on the drivers side top of the carb, but absolutely positively make sure you annotate how much you move it. 1/4 turn, 1/2, etc. The CCC carbs may be just like EFI, since you are affecting the TPS by increasing the idle like this.

    I haven't heard of anyone selling rebuilt or new CCC carbs, when you could find them they were insanely expensive. You might just consider a swap to TBI since you'd need to do it smog legal.

    The TPS in those carbs seems to be very failure prone, along with issues like worn out throttle shaft bores. TPS shouldn't cause the stalling issue, but bad TPS, couple with bad throttle shaft bores, could cause some issues. You could try searching for a vacuum leak with propane or the like as well. Good inspection of the vacuum lines, etc., can't hurt.
     

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