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Thread: l36 top swap has bad hesitation and makes no power

  1. #1
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    l36 top swap has bad hesitation and makes no power

    Hi,
    I have a 98 Intrigue that was running a 98 GTP motor and everything was great except a slight stumble when going over 3k for a few seconds. Timing chain gear let go and I kissed a valve with the piston. I swapped out just the block with an L36 block. Now it hesitates, bucks and stumbles anytime boost kicks it, I can get it to run ok if I give it slight acceleration over 30mph. Engine has XP cam with 2 degrees of of crank advance, 130# springs and 1.65 rockers with stock heads. Gen 5 with N* maf, 42 lbs injectors, headers, 3" down pipe to catless 3" exhaust, 2" intercooler, Aremotive fuel pump. I run a 2.8, 3.0 and a 3.4 pulley and it still does but slightly goes away with the bigger pullies. All this worked and made 400 crank hp in June 18. Any ideas for where to look?
    Thanks Steve
    Last edited by 98scintrigue; 2 Weeks Ago at 08:14 AM.

  2. #2
    Tuning Addict 5FDP's Avatar
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    Sounds like either spark issues or it can't get enough fuel but I have no logs with a wideband to view.
    2012 Silverado CCSB 5.3/6L80e, slow and heavy.

  3. #3
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    I have a log from when it started doing it.
    Attached Files Attached Files

  4. #4
    Tuner ZeroBoostBuick's Avatar
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    A bit more details be good.

    You said a valve smoked a piston when the chain let go... So, you replaced the block and kept the head that had the bad valve and you replaced the valve, the valve seat, the pushrod, the rocker, the spring etc... and all the stuff that makes that valve work ??? right ?

  5. #5
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    I had a machine shop check it all out. I did finally find one of my issues. I was blowing the spark, adjusted the plug gap and now it runs like it did before everything happened. I am now running into issues with the fuel. I need to adjust it for the changes I did. I am new to HP tuners so I have been messing with it but am not getting the results I am looking for. I have a hesitation from 2k to 3k under mid to full throttle and some hesitation randomly at the top of my rpm window. I think it is to rich all together since I installed the L36 block due to the higher compression, not 100% but I am still learning. Can some one tell me where to go to adjust my fuel curve. Thanks Steve

  6. #6
    Tuning Addict 5FDP's Avatar
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    Verify fueling with a wideband o2 sensor before blinding adding fuel to the engine.

    Basically all your fueling corrections will done to the MAF curve.
    2012 Silverado CCSB 5.3/6L80e, slow and heavy.

  7. #7
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    My wideband gauge shows my AFR at cruising at 14.7 and when I touch the pedal in any way it drops down to 10.1 to 11.3. WOT is the same readings but I have seen 9.6 once. My dyno guy said to lower it 2 to 3% to see if the hesitation issues go away or get worse for a temp fix. I have a dyno session in a few weeks and then he will fine tune it there. I dont drive the car much but want to keep it from going to lean and hurting it.

  8. #8
    Tuner ZeroBoostBuick's Avatar
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    Zero out the RPM adder in the Power Enrichment and set the Base AFR vs ETC to 12.5 (instead of 12.1) from 86 to 230 f. You can zero out the Add vs TPS table also, and set the throttle HOT to 35 all across.

    In Torque Management / general / spark retard, zero out that whole table too.

    Then do a search for "MAF tuning" and tune the MAF.
    When tuning the MAF, I would aim for 12.5 AFR at full throttle. If you get knock retard, then enrich it a little bit at a time. But there is no reason to have AFR at full throttle below 12 with your setup, but usually 12.5 will make better power than 12.0, unless you got knock.
    Spark tuning is another thing to work at.

    Transmission is another chapter. But best to do one thing at a time.
    Last edited by ZeroBoostBuick; 2 Days Ago at 08:42 PM.