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Thread: 95 LT1 throttle response

  1. #1
    Fuel Injected!
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    95 LT1 throttle response

    I'm working on a 95 Camaro with a LT1 with a nice cam and headers. I have it cranking and idling good but this thing has no throttle response.
    When I hit the throttle it will lean pop then bog out before it finally accelerates.

    I'm using Tunerpro and for the life of me I can't figure out what table would increase the (for lack of a better word)"pump shot".

    Most of my tuning has involved my 89 Camaro running the '7165 6E ECM. I know my way around 6E but this EE is making me think too much.

    I know there are a few LT1 guys on here so please point me in the right direction.

    Thanks in advance,
    Dewayne

  2. #2
    EFI GearHead ! EagleMark's Avatar
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    Don't remember there being one?

    Wish I'd have had more time with my LT1 before it got wrecked... one of the major issues is no completed dissasembly. Rocko has a thread with one started but we have not had a taker to complete it. There's lots of things missing.

    That said guys have tuned them with tricks and tweaks. First thing needed is to run Speed Density and get the VE table in order, still better to do Open Loop with a Wide Band.

    Depending on the cam, if your idling OK, look at data and see what BLM, INT and o2 sensors are reading? It may be way off! O2 sensors are known to lie with cams at idle...

    Next issue with long tube headers? Moves the O2 sensors so far that INT delay is way off! That's a parememter that is missing even in TunerCat.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  3. #3
    Fuel Injected!
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    I locked the BLM's at 128 and had a WB in hooked up. I got it starting and idling really nice and was also able to get the throttle response a lot better than it was. I tuned a LT1 Camaro for this guy a few years ago and it turned out really nice. With that being the first LT1 for me I made a log of what I changed and the results after the change. I found that log after starting this thread yesterday and it was a great help.

    The car wouldn't crank when it got to me. It's a 96 with a 95 Pcm and the Vats was enabled. After getting the cranking idling and throttle response close I was gonna to a test run to datalog, the car would not move forward or reverse.
    Too bad the owner didn't take time to put transmission fluid in before hauling it to me.

    Thanks for the reply

  4. #4
    EFI GearHead ! EagleMark's Avatar
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    Trans fluid would be good! Wonder if tranny is any good now?

    What's on the log list?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  5. #5
    Fuel Injected!
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    Just got home with some fluid so I will know if the trans is good in a few minutes.

    The log just had common stuff like changes to Ve tables, %Change To Fuel/Air Ratio Vs. RPM at WOT...... such as that. It was just my way of not forgetting what I changed from one test run to the next.
    %TPS Threshold For WOT Vs. RPM helped more than anything on throttle response. It's not the table I would have preferred to use but I didn't see anything else that may be better.

  6. #6
    Fuel Injected!
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    I have an LT4 HotCam 214/228 112 lsa, make sure your IAC counts are at 30's or above at idle, LT1's love idle air coming from the intake idle air passages feed by the IAC valve and not much if any from the TB blade (stop screw setting). Getting the TBS closed voltage between 0.45 and 0.75 and IAC counts at 30+ may take a couple of tries. Depending on the cam, increase your closed TPS timing in the 400, 800 and 1200 ranges from stock 19-20* to high 20's to low 30's till you get smoothest idle and lowest MAP (highest vac). 750 is a good idle speed to shoot for in a cammed A4, 800 in an M6. Next look at where you move from closed spark timing into main spark table and make sure when you enter main and move through it you do not have a big negative timing jump. The bigger the cam the more chance of split BLM's at low end and idle, make sure your BLM's look good. Is your TB stock ?? Some aftermarkets have some problems idle air flow..
    I'm Bob 1994 Z28, A4, CAI, Cam, 1.6RR's, LT's, stall, cat-back, tuned w/TunerCat $EE and TTS Datamaster. 1995 Chevy G20 conversion van, 5.7L A4 stock no tune..

  7. #7
    Fuel Injected!
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    The transmission did work after adding fluid.
    IAC were at 4? if I remember correctly. Throttle body is stock. closed throttle is at 32 and 30 when it moved into the main table.

    Thanks for the help guys, I'm about to go play with it some more...... Well after I go to the store for gas since his gas tank matched the transmission..... empty.

  8. #8
    Fuel Injected!
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    So it seems that if you lower the "MAP Threshold To Enable WOT" constant then increase "%Change To Fuel/Air Ratio Vs. RPM at WOT" at lower RPM's the throttle response improves greatly.

    Or at least it worked for me.

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