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Thread: my 454 swap

  1. #1
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    my 454 swap

    Swapped in a 74 454 that I added a stock vortec cam to.
    Using 92 454 throttle body. computer is 7747 prom is ANTY, but is a hypertec. I got the number for the prom using my scan tool.

    The problem is the idle speed ends up at 1000-1100. I do the whole min set procedure, my book tells me 700 in gear. When I finish the procedure and restart idle speed is slightly higher than min, with IAC counts in the 35-40 range. A few restarts later, the idle creeps (1000-1100) up even though IAC is at 0. And it is completely seated. There are no vac leaks and I have tried backing the timing down from 4 deg and it doesnt really help.

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    Fuel Injected! JeepsAndGuns's Avatar
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    If the IAC goes to zero counts, then it sounds like the throttle blades are too far open. They usally wont do this untill engine is warm. I did this when I was new to tuning. I guess I had set the min idle when the engine was not warm enough. As for a long time I couldnt get it to go to 650 rpm idle like I had set, I then noticed my iac was at zero! Reset my min idle and all was well after that.
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    RIP EagleMark's Avatar
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    ANTY has a flat 750 RPM idle for all temps in "IAC - Desired C/L Idle Speed" I didn't look for any other changes.

    To do the Min Air set procedure motor has to be totally warmed up even rev the engine after warmed up for a minute if you can't drive it. Then has to be in Closed Loop. If your getting 0 IAC counts and 1000 RPM with no vacuum leaks then the throttle blades are open to far.

    Also ANTY has been superceeded twice, once to ATPX, then to final version of AZFT. I don't know why it was updated by GM but it may have issues, twice!

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    well I will wait till the exhaust is done up before I mess with it anymore. The o2 is fresh and is the same one I used with the 350. Thanks for the replies

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    RIP EagleMark's Avatar
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    Just looked at that bin some more and it is an Open Loop idle bin. Will have to make some changes to be closed loop idle...

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    Check the throttle shaft play in the TBI , the BBC TBI's are notorious for elongating the holes the throttle shaft rides through , causing the exact problem you describe.

    As others have said , if the IAC counts are at zero , un metered air is entering somewhere or the throttle blades have been opened up too far .

    Does it do the idle creep with and without your scan tool hooked up to the ALDL port , some of the different scan tools I have come across would cause an idle creep if left hooked up to monitor data , never could really explain it ........

    TOM
    Last edited by Nasty-Z; 05-01-2012 at 07:53 PM.
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    Quote Originally Posted by Nasty-Z View Post
    Check the throttle shaft play in the TBI , the BBC TBI's are notorious for elongating the holes the throttle shaft rides through , causing the exact problem you describe.

    As others have said , if the IAC counts are at zero , un metered air is entering somewhere or the throttle blades have been opened up too far .

    Does it do the idle creep with and without your scan tool hooked up to the ALDL port , some of the different scan tools I have come across would cause an idle creep if left hooked up to monitor data , never could really explain it ........

    TOM
    The scan tool does have a small effect on it. I have seen that on some of the tbi stuff where with the scan tool connected they idle 1000+.

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    Well as an experiment I put my 350 prom in to see what the idle will do, and it works just like it should.

    I drove it some with the 350 prom, and there was some very slight lean sags till the block learn crept up, and after that it runs very good. wot is actually richer with the 350 prom (.960 vs .900)

    What is the range of blm, the 454 prom while driving runs about 140-160 blm, and the 350 prom runs 150-180.

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    Quote Originally Posted by black dawg View Post
    The scan tool does have a small effect on it. I have seen that on some of the tbi stuff where with the scan tool connected they idle 1000+.
    That usually means it is in ALDL mode, idle RPM is set to 1000. I beleive it also changes spark too...

    The 350 prom is just totally differant then a 454 prom.

    Like I said above the 454 chip you have is open loop idle and been updated twice. The 350 prom is idling correctly because it's a closed loop idle prom.

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  10. #10
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    would it be better to tune on the 454 chip? can it be made closed loop idle? Or would it be easier to just make the 350 chip match the 454 engine.

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    Swapped in a 74 454 that I added a stock vortec cam to.
    Cam from 96 or newer engine? Did you add roller lifters as well?


    Does it do the idle creep with and without your scan tool hooked up to the ALDL port , some of the different scan tools I have come across would cause an idle creep if left hooked up to monitor data , never could really explain it ........
    Because some scanners use "10k" or "ALDL mode" which enables different settings in the calibration for testing and diagnosis.

    Old trick for setting minimum air is to cut a strip of paper 1/4" wide then close between throttle plate and bore at 90 deg to shaft. Proper setting gives slight drag when paper is pulled out. Do when engine is warm for best results.

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    Used retrofit rollers and the gen 6 timing set and cam retainer.

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    Fuel Injected! JeepsAndGuns's Avatar
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    Quote Originally Posted by black dawg View Post
    would it be better to tune on the 454 chip? can it be made closed loop idle? Or would it be easier to just make the 350 chip match the 454 engine.
    If the 454 bin you have has been superceded twice, and the 350 bin you have runs significantly better, then I (just me personally) would tune that bin.
    Just my $0.02 worth.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

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    RIP EagleMark's Avatar
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    I'd agree with JeepsandGuns if that was the only 2 bins I had. But we have plenty of 454 bins to start with including the AZFT it was superceeded to.

    Yes you can make that a Closed Loop Idle bin but then it has been superceeded twice, so I'd still start with a differant one like the AZFT it was superceeded to.

    I've also used the AZFT a few times for a starter tune and had no issues.

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    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  15. #15
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    Well, I got the 454 prom to work for me. It seems my balancer has slipped, so timing was way to advanced. I also lowered my fuel psi from 15 to 12 and this leaned it out to where it works. I think these injectors are to sloppy, because I have never seen that little of pressure change affect the o2 as much as this did. The injectors do look drippy at cold start.

    what would you expect to see for warmed up open loop idle o2 readings at 3500ft? I am .89ish
    what would you expect for WOT? I get from .96-1.0

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