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.

Where should the wire go? Coil and distributor...

Discussion in 'The Garage' started by Fubeca, Dec 18, 2003.

  1. Fubeca

    Fubeca 1/2 ton status

    Joined:
    Dec 18, 2002
    Posts:
    2,100
    Likes Received:
    2
    Location:
    Denver Area
    I have a stock 1991 5.7L TBI. What I think is the coil has two sets of two wires coming out of the top of it. One set goes to the distributor and one of the wires (red I think) from the other set goes somewhere. The other wire (tan) is pretty short and has a little connector on it but has never been connected to anything since I've had the truck. Should it be? Is this why I can't run 85 octane fuel and it pings going up hills?
    I'll try and get a pic up tonight.

    Thanks
     
  2. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    That wire is for your Tach. If you dont have a Tach it should be disconnected.
    85 is too low octane for TBI trucks. Thats prolly why it pings. If I rember right, the owners manual recomends at least 87 octane. All I run in mine is 89 it doesn't like 85 at all.
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

    Joined:
    Sep 1, 2001
    Posts:
    8,972
    Likes Received:
    0
    Location:
    Peoria, AZ
    The red wire from the grey connector (the one that doesn't go to the distributor) is your coil 12V power wire. It is connected to a keyed source. The other wire is your tach wire and like mentioned above goes no place if you don't have a tach.

    Harley
     
  4. R72K5

    R72K5 Banned

    Joined:
    Mar 5, 2001
    Posts:
    8,905
    Likes Received:
    0
    Location:
    central IL
    tan wire exists whether you have tach or not, on the 75-86 style large HEI the tan wire pluggged into the tach terminal on cap yes but did evne with no tach, it was most likely for monitering purposes for the timing control box but in 87-up years most likely is same, but now for the ECM, which might explain why ther ECM is not adjusting your timing for lower grade of fuel, but if you jcheck your owners manual you might find that youre not supposed to run so low of a grade of fuel as 85, i would get no less than 90 for it, yues it costs more, but if thats a problem, then maybe you have the wrong vehicle as a daily driver ?

    hope that helps

    good luck
     

Share This Page