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Lack of power after engine swap with codes...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 89GMCSuburban, Jan 7, 2003.

  1. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    I just swapped my engine out for a .40 bored 350 with a mild cam in it and it ha no power increase over the old tired engine. When cruising down the road or aggressive driving I get a code 43 and 45. Gas mileage is worse than with the tired engine. Timing is right on 0 degrees and the distrubutor is all new, including the module.
    02 sensor is new
    knock sensor is new

    What could this be? Vacuum is reading strong so I don't know what the problem could be. Any ideas??
     
  2. HarryH3

    HarryH3 1 ton status Author

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    Code 43 means either that the knock sensor input to the ECM has been stuck low for more than 5 seconds, or that the ECM advanced the timing to the point that it expected the engine to go into slight detonation, but the knock sensor never reported any detonation. This is a self test that is performed once each time the engine is started, after it reaches operating temp.

    Code 45 means that the O2 sensor has reported that the engine is running way too rich.

    Your new cam may be confusing the MAP sensor and screwing up the fuel curve. An engine that's running too rich is also much less likely to suffer from detonation, so that could explain the Code 43.
     
  3. Thunder

    Thunder 3/4 ton status

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    What are the specs on the cam?
    The computer doesn't like cams with durations over 212 degrees.
    Make sure all the sensors and smog stuff are hooked up right.
     
  4. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Cam specs are:
    Cam lift: int= .280 exh= .295
    Valve Lift: int= .420 exh= .443
    Lobe Centers: int= 107 exh= 117
    SAE Duration: int= 270 exh= 280
    .050 Duration: int= 204 exh= 214
    SAE timing: BTC= 27 ABC= 71 BBC= 76 ATC= 32
    .050 timing: BTC= -5 ABC= 29 BBC= 44 ATC= -10
    Valve overlap (according to Desktop Dyno)= -15

    It's an Elgin Pro Stock cam (says on box)...this cam was installed at the place I bought the engine, it was a $50 option on the engine so I said go for it...the one that would've come with it was re-ground. (oh, hell no!) I'dve had flat lobes in two months.
    Run on Desktop Dyno, this cam alone with nothing else would increase power to 235hp @ 4,000 and 347 ft.lbs. @ 3,000.
    P.S. Would it be a good idea to run medium grade gas all the time with the cam? I'm running Regular now and it's running good with no pinging, but would running a higher octane make any difference? (I know it would in a compression change)
    Thanks guys!
     
  5. Thunder

    Thunder 3/4 ton status

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    The cam looks like it should work ok with the computer.
    When the timing was set. Was the Black and Tan wire(timing bypass) on the frewall disconnnected.? If not your timing will be way off.
    I set my timing on my TBI 350s around 4-6 degrees.
    You should be using 87 octaine or higher in your engine. The computer is set up to run on 87 octaine.
    Just a guess but.....
    You also might want to make sure the valves are adjusted right.
     
  6. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Yeah, I disconnected the timing thing, but I have it set at 0 degrees...that's what it says to do on the tag. Lately, it's been getting some more balls, I think the engine is just sealing itself up finally. Regular here is 87 octane, middle grade is 89. I used to always run 89 just because my engine had a little more balls, but that crap is getting so expensive...
    The valves were set at the engine shop and they tapped the stud and nut to make sure they wouldn't back off.
     
  7. imiceman44

    imiceman44 1 ton status

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    Actually if you want more balls go lower octane.
    There is a misconception that higher octane is better.
    It only prevents detonation which actually is power, too much power.
    octane is the ability to burn only on a spark and slowly.
    the lower octane burns faster.
    You should always run the lowest octane rating that your engine will accept.
    If you want to make it better, put some valve cleaning additives and clean the valves and combustion chamber so you can run lower octane rating.
    /forums/images/graemlins/thumb.gif
     

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