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.

Engine diagnosis help

Discussion in 'The Garage' started by ftn96, Mar 29, 2002.

  1. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Not getting any coses still. And no I haven't used a scanner yet either. But after the headers, new cat, new heated o2, distributor cap, rotor, wires plugs, PVC, fuel filter, and fuel pump...... IT is running better but it is still idling up and down (smooth to rough). And even when driving at city cruising speeds like taking off from stop lights and stuff its hesitating still, just like the idle situation but with more RPM's. So something is restricting it from spark, fuel or air. Any ideas on what would be the culprit next? EGR is what I was thinking. And no I dont appear to have any vacum leaks, OH wait except for that (I guess is the MAP sensor, bolted to a bracket right above the passenger valve cover out to the side of the TBI, has 2 outlets/inlets for vacum lines. 1 is going directly to the EGR diaphram assembly. Is that the EGR control or is that the MAP or MAF sensor? What ever it is, one of the inlet/outlets doesn't have a line hooked up to it, not can I find a place anywhere in the engine compartment to hook it up. Ideas?

    <font color=red>***Update***</font color=red>
    THought it was the timing chain being so stretched that it the crank would turn almost 6 degrees before the rotor would start to turn. Just test drove it. No change.
    #1 I also dis-connected the Ignition to ECM wire. Drove it around...No change.
    #2, Dis-connected the Egr control Solenoid....No change. Disconnected the O2 no change.
    #3, Looked at the spray from the TBI injectors...Looks smooth.
    #4, Checked the timing, dead on at 0 degrees, but ever so often it would jump around erratically for a 1/2 second or 2 then back to straight 0 degrees. **This doesn't sound normal, does it? ** What would cause this but not cause any codes or any normal symptoms? Im on my last straw here guys!!!! I need some Help on this....<font color=red>**BAD**</font color=red>
     
  2. Scooter

    Scooter 1/2 ton status

    Joined:
    Nov 18, 2000
    Posts:
    551
    Likes Received:
    0
    Location:
    Grandview, Mo.
    I believe what you are talking about is the EGR control solonoid. There's 3 ports on it, 1 on one side 2 on the other. The single port goes to the base of the TBI where it shares a vacuum port with the AIR stuff (at least it does/did on my 87). The side that has 2 ports on it one of them is "active" the other is a vent. The "active" port has kind of a barbed end on it while the vent is smooth.

    After I put in my new motor and replaced just about all of the sensors/senders I ended up just plugging the EGR vacuum line. That cured the off-idle stumble (it would literally stumble so bad it would die most times between 1300-1500 rpm) and smoothed out the idle quite a bit on mine. So far the only code I get with any type of regularity (about once a week) is 45 - Rich exhaust ...

    HTH
     
  3. Burt4x4

    Burt4x4 3/4 ton status

    Joined:
    Feb 17, 2000
    Posts:
    6,854
    Likes Received:
    0
    Location:
    California (Modesto area)
    Dang dude!! Sorry ain't got no ideers fer ya/forums/images/icons/frown.gif
    Good Luck!!
     
  4. Mreetz

    Mreetz 1/2 ton status

    Joined:
    Jun 26, 2001
    Posts:
    1,282
    Likes Received:
    0
    Location:
    Subs of Denver, Colorado
    Could be vacuum leak. Check to make sure you have them all plugged or connected.
     
  5. Ddragggon

    Ddragggon 1/2 ton status

    Joined:
    Apr 25, 2001
    Posts:
    2,657
    Likes Received:
    0
    Location:
    Hartford, WI (formerly Etiwanda, SoCal)
    I have this problem on my 73 350, and it all started when I replaced a shot points distributor with an old HEI distributor. as it turns out, the entire distributor is worn out enough that as it spins, the shaft has enough slop in it to change its timing ( the shaft moves up and down inside the distributor itself, as well as side to side) this is the only part on mine that I havn't replaced ( except for the timing chain, but I'm still holding off on tearing the front of the engine off) and the only thing I can think it is ( new cap, rotor, timing weights, advance springs, wires, plugs, header gaskets, and soon a new carb, and hopefully distributor)

    of course, since yours has emissions sticking out of it everywhich way, it could be anything /forums/images/icons/crazy.gif

    good luck with it, and let us know,

    -Rich
     
  6. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    To tell you the truth, even thought its a 90 it doesn't have that much emissions stuff on it, much to my suprise I might add.
     
  7. Ddragggon

    Ddragggon 1/2 ton status

    Joined:
    Apr 25, 2001
    Posts:
    2,657
    Likes Received:
    0
    Location:
    Hartford, WI (formerly Etiwanda, SoCal)
    somewhere towards the end of the 80's, common sense struck someone, or something, and they realized that most of the emissions systems they were putting on were making them not only underperform, but get worse emissions on top of it. IMHO, the worst era for emissions was 79-84 for just about all vehicles... that was when they put every emissions system ever invented under the hoods of all cars/trucks produced. they almost needed a second engine to run the emisisons systems for the first one.

    oh well, glad mine're emission free.

    -Rich
     
  8. Philly87

    Philly87 1/2 ton status

    Joined:
    Jul 14, 2000
    Posts:
    465
    Likes Received:
    6
    Location:
    El Paso, TX
    Just a thought. Have you checked to make sure the gasket between the throttle body and the intake manifold is not sucking air. I know you said you had no vacum leaks but that can be easily overlooked sometimes. Happened to mine.

    Phil
     
  9. MudbogAD

    MudbogAD 1/2 ton status

    Joined:
    Jun 29, 2001
    Posts:
    672
    Likes Received:
    0
    Location:
    Las Vegas Nevada, US
    Maybe it's your timing
     
  10. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    I wish or hope that it is something that simple. But it seems to be inconsistant with common characteristics of timing issues. It seems more like something to do with the computer relating to the new headers. Which points to the EGR or a vacum leak. And to this point I have yet to find a vacum leak.
     
  11. Burbinator

    Burbinator 1/2 ton status

    Joined:
    Sep 14, 2001
    Posts:
    898
    Likes Received:
    0
    Location:
    Tempe, Arizona
    I would first hook up a vacuum gauge to a manifold source so that you know you're on the right track vs. a wild goose chase.

    Another thought might be a knock sensor...just a thought if your vacuum is 4.0
     
  12. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Well, I changed the CTS and cleaned the Shinola outta the TBI and it almost seemed to run better..(i thought it was in closed loop) then it went in closed loop and no dice. Still doing it. So That narrows its down to TPS, EGR, MAP or sell this MF!!!/forums/images/icons/mad.gif
     
  13. Hossbaby50

    Hossbaby50 3/4 ton status

    Joined:
    Sep 1, 2001
    Posts:
    8,972
    Likes Received:
    0
    Location:
    Peoria, AZ
    I'll give you $5. /forums/images/icons/smile.gif
     
  14. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

    Joined:
    Jul 18, 2001
    Posts:
    5,693
    Likes Received:
    0
    Location:
    CA
    If the bidding is gonna start...
    I'll give you $10
    Plus shipping.
    Or just tell me when and where I can pick it up and I'll have a nice crisp $10 bill for ya 'bro! /forums/images/icons/smile.gif
     
  15. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    /forums/images/icons/laugh.gif Not Hardly. Just got off the phone with an old Navy buddy adn he gave me several options for free troubleshooting before I spend any more money. But I did however, find a place today that would run a diagnostic scan for $49.99. Sam's Master Muffler. They build race cars at night after hours in the shop and have all that computer stuff, plus....dude says he's got a Chevy step side with 40x18 TSL/SX's on it. So I'll at least get a new contact out of the or-deal. /forums/images/icons/smile.gif
     
  16. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,368
    Location:
    E-town baby!
    My money is still on the EGR.../forums/images/icons/smile.gif but let us know when you finally get it figgered out.

    Rene

    PS they don't make a 40x18 TSL/SX.../forums/images/icons/tongue.gif
     
  17. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    I hear ya. Rene. We'll see. /forums/images/icons/cool.gif
     
  18. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Too funny though, Rene! Your screaming EGR, Haynes is Screaming TPS, Chad, navy buddy is betting on ignition module or the IAC and Im freaking clueless. Lets see what the computer has to say and go from there!
     
  19. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,368
    Location:
    E-town baby!
    Well hopefully whatever it is is not too spendy and you'll end up with an awesome running truck!

    Rene
     
  20. Hossbaby50

    Hossbaby50 3/4 ton status

    Joined:
    Sep 1, 2001
    Posts:
    8,972
    Likes Received:
    0
    Location:
    Peoria, AZ
    Do you know a friend with a similar year K5 that would let you borrow parts off there rig for testing purposes. Or possible buy a part from the part store, test and see if that is the part, and if not return it and say you didn't need it and you didn't use it. It would only have to be on your rig for a few minutes to test. Most likely they would never know. Not the most moral or fixes, but fixed none the less. Just a couple of options.
     

Share This Page