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Thread: LT1 trouble shooting help

  1. #1

    LT1 trouble shooting help

    So as many of you know I was running around to all of the LT1 knowledgeable (or sometimes just anyone) getting help to get my engine back in shape over the weekend at Hallett. First off thank you as always for the assistance everyone is always willing to give. Unfortunately I was not successful and have not been successful up to this point. Below is what I have done up to this point and what I felt in the car.

    It ran great Friday morning. Midway through the session right after lunch I just started loosing power. At first I thought I was just not carrying enough corner speed and subsequently exiting at a lower RPM. It got worse fast though. We had noticed after session one that my water pump had started to leak from the weep hole so I planned on changing it that night. when I started loosing power I assumed that the Opti had gone bad from water getting inside or something.

    Replaced those that night. On Saturday for warm up..... same problem. Also the plug wires where on their last leg so went ahead and put news ones on as well. I checked all the spark plugs that night and gaped them. A few looked a bit too white but they did not correlate with the dead cylinders that I had.

    We found out that the back three cylinders on the driver side were not doing anything. We determined this by pulling the injector plug on each cylinder one at a time and then replacing it to see if engine reacted. I know I had air because..... well I have no reason to think it would not be getting air. I know it had spark because after replacing the opti i pulled a spark out of one of the dead cylinders and had Tyler turn the car over. Shocking the crap out of myself confirmed that we had spark. Last but far from least I know that the injectors were at least firing because you could feel it and Tyler put a screw to each one and against his ear and could hear them. I at the time what I did not know is whether or not fuel was actually making it through. I ended up find out that Curtis had injectors in his trailer so i put those on. Still no fix.


    Back here I ran a compression test. Every cylinder was between 125 and 135psi. Measured fuel pressure at idle with vacuum line pulled from the FPR, 42. With Vacuum line on and on the road, 34-38 WOT.

    I am hopefully going to be pulling the codes this weekend, so hopefully that sheds some light. That being said, at this point if anyone has ideas I am all ears.


    BTW is Curtis on this forum? If so what is his username, I have some injectors that I need to mail back to him.

  2. #2
    Senior Member Carroll Shelby Fbody383's Avatar
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    You did measure fuel pressure and check the fuel regulator not leaking? Might not hurt to pull the fuel rails and make sure there is nothing in them.
    #39 CMC Camaro
    Orange is Fast!
    CMC-NT01 FTW!

  3. #3
    Senior Member Carroll Shelby ShadowBolt's Avatar
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    From what I have seen the fix for a LT1 is an LS1 swap. In the Ford camp we are working the 4.6 and the 5.0 hard to get to the current CMC numbers. The LS1's are just coasting at CMC power levels. If I could drop an LS1 in the 55 I would be all over it. I know this is not the answer you are looking for but I would not spend much money on trying to fix a LT1.

    JJ

  4. #4
    Senior Member Grass-Passer MikeP99Z's Avatar
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    Pcm?

  5. #5
    Check the float bowl levels

  6. #6
    Quote Originally Posted by Mike View Post
    PCM?
    I do not think that is bad but I should know this weekend since I am going to trying to pull codes.
    Last edited by liquidroam; 06-22-2018 at 10:13 AM.

  7. #7
    Quote Originally Posted by Trublu View Post
    Check the float bowl levels
    ????? Float bowls... we are not talking carbs here. Maybe I about to look really dumb but I did not think I had float bowls with EFI.

  8. #8
    Quote Originally Posted by liquidroam View Post
    ????? Float bowls... we are not talking carbs here. Maybe I about to look really dumb but I did not think I had float bowls with EFI.
    They are hard to find....

  9. #9
    Quote Originally Posted by Trublu View Post
    They are hard to find....
    Touche

  10. #10
    Were the dead cylinder's exhaust tubes getting hot? I've been fooled by the injector test before.

    Disassemble the whole intake path, I had a MAF clogged with rubber at cresson. How are the O2 sensors? Maybe lost a sensor and is in limp mode?

    Skipped timing chain??
    Last edited by Sook; 06-22-2018 at 03:19 PM.
    CMC #50

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