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Code 45 on 89 TBI 350 and stumbles..long

Discussion in 'The Garage' started by TJS, Jan 11, 2004.

  1. TJS

    TJS 1/2 ton status

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    Location:
    Westport,CT
    Ok,
    History:
    Swappped out a tired,knocking 350 TBI for someone. I still have the truck at my shop. It is a friend of a friend. He brought me a J/Y motor which I do not like doing. Anyway, I had to extract the studs in the manifold to y-pipe cause they broke (rusted). He also told me that someone had tried to get the 02 out and could not. So I figured while I had the manifolds off I would heat it up and get it out. He got a new one a couple of days later and the motor was already in the truck. I was wondering to myself, why the other person was trying to get the 02 out...hmmm. So I tried putting the new 02 in the manifold while it was in the truck. When I heated the manifold near the 02 I must have distored the threads a little. So the new 02 would not screw in at all. Now I was kinda heated cause I am doing a favor and not really making any money and a new tap for these are 50.00. So I was able to screw the old O2 in.
    Also while I had the dist out, I put in a new pick-up, module, cap, rotor and wires (all GM parts). I got the truck running yesterday and set the timing (in timing mode).
    Anyway I drove it for a while today and when fully warmed up it stumbles and hesitates off idle. I finally was able to get a code and it is code 45. So I checked in a How to repair and Mod. chevy F/I. I have not had time yet to hook up a DVOM to the o2 sensor circut at the ECM. This truck was not taken care of at all. I do not know if the fuel filter has been changed. I will ask the customer tomorrow and I will also ask him if he had a C/E light and hesitation. I bet he says he never had a prob. Any help would be appreciated.
    T.J.
     
  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Check the ECM's temp sensor. My 88 is a bit cranky till fully warm like that. I'm leaning towards a temp sensor holding it open loop to long.

    Also check the EGR is properly hooked up. Ifi it has the control solonoid it may be hangining and keeping EGR on a little at idle.
     
  3. TJS

    TJS 1/2 ton status

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    The ECM temp sensor is brand new. The engine came with a TB intake with an EGR. I think I may take the EGR off the old engine and put it on this one. It does feel like the EGR might be hanging open when it should close.
    T.J.
     
  4. yunit

    yunit 1/2 ton status

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    If it is hesitating just off of idle and does not have the power it should when you give it some gas than it is probably the EGR. Disconnect the EGR and plug the line, if the hesitation is gone then it is the EGR, just make sure to repalce it or the MAP sensor get's messed up and makes the truck run richer & richer until it won't start...ask me how I know. /forums/images/graemlins/grin.gif
     

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