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Thread: 5.3 swap big cam, card maf start tune

  1. #1

    5.3 swap big cam, card maf start tune

    I have a 40 Plymouth that I put a 5.3/4l60 into with a comp cams 54-454-11 cam and a card style maf (ls3) im trying to get it started but it seems to be super lean at idle and I cant seem to fatten it up. im a total rookie, what parameters should I weak just to get it to a rich idle kind of situation? heres the tune I tweaked a bit last night bumped idle to 850 messed with timing a bit pulled codes and stuff of course. any help is of course much appreciated. thank you
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  2. #2
    Tuning Addict 5FDP's Avatar
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    May 2012
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    Without knowing if it's really lean, it's hard to tell you what is up.

    You need a wideband o2 sensor to tell you how the fueling is.

    That MAF calibration isn't exactly cut and paste into a GEN 3 computer. The size of the tubing will also play a huge roll in how it runs. A larger tube size will make it even leaner.

    Does it have a intake air temp sensor built into the sensor or did you wire in a separate one?

    How is fuel pressure, solid at 58psi?

    Any vacuum leaks?

    You'll probably want to cut the idle over/underspeed spark correction tables in half too, so it can't swing the timing as well much. And zero out the EGR spark correction too.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
    Advanced Tuner
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    Sep 2017
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    Wouldnt he need the ls3 IAT calibration for gen3 as well?
    1997 30th SS. Torqhead 24x, TFS heads, 234/244 cam, 4l80e, Dana 60.

  4. #4
    thank you guys for the replies! the car is at the trans shop right now getting a freshie put in it. ill put the wideband on it as soon as it gets back. before it went to the trans shop I was able to tweak the ve to fatten up the idle but bank 1 still seemed to be lean on the ltft and narrowband readings. gonna go through everything, double check vacuum leaks and all of the basic stuff when it comes back and get the wideband in there along with the timing tweaks that 5fdp touched on to get some real data. thank you guys again for your input. ill get back to you with a log file hopefully next week sometime. I cant thank you enough for your help! cheers fellas.
    Last edited by Street Performers; 06-20-2019 at 04:14 PM.