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Thread: 6.0 sloppy stg 2 cam swap problems tuning

  1. #1

    6.0 sloppy stg 2 cam swap problems tuning

    Hi there fine people of the hpt forums, I will start of by saying I am really new to the hp tuner thing, and I am like a sponge when I can see and understand whats being done, thing is values in vcm while logging are hard for me to understand, I here have a 1987 chevrolet that I rebuilt from nothing basicly, and put in the most common stuff in there, my cam is the elgin sloppy stage 2, has 585/585 lift 112 degrees, the motor has not been to a machine shop but!! the the best of my basic knowledge on rebuilding engines, things were really in great shape and did not need a whole lot if any work done to in by the looks of it, now for the fun part, I have leak tested the engine and perfomed a compression test after the engine ran a while, 150 psi across the board and no leaks to be found vaccum or exhaust, wiring wich I have done myself with the help of the interwebs was triple tested, continuty and signal coming from and going to pcm, o2 sensors are brand new bosch units, thing is I cant have a normal stft reading, when engine idles my bank 2 sensor is showing -35 and bottoms out!, on part throttle it looks ok but why is my bank 2 sensor showing negative instead of positive? when I tune I tune with everything off, maf, stft, ltft, pe, dfco, fuel cutoff etc like it is said almost everywhere i look, my base ve looks to be ok when in OL, running 13.5-15 afr all across the board, but then when i try turning stuff back on thats what happens, then I run super lean on part throttle cruising and bank 2 is way in the negative, I will provide here my current tune file and the last 2 vcm scan performed while cruising around, first will be a VE tuning file, with fuel adjustments in mind, then second one will be with all back to normal , still having issues with my maf but still needs adjustments there, and I thank you guys in advance for the help, it has been a long process to learn from all sorts of sources, but I20-07-07 20-43-50.hpl20-07-07 19-21-46.hpl6.0 c10 ve maf on after ve tuning.hpt6.0 c10 ve maf off.hpt really need to have the right information to keep moving,

  2. #2
    Where is the wideband located? If you have it located in Bank 1 then it's likely you have a defective o2 sensor on Bank 2 or you could have an injector issue.

  3. #3
    both o2 are right after the vbands after exhaust manifold, both vbands dont leak, both exhaust gaskets are brand new multi layer steel, wideband is on bank one but i have another sensor on bank two, i had a innovate motorsports dlg-1 but wasnt working well, so i switched to an aem and i have readings on my bank 1, just need to connect and calibrate second sensor to get my b2, and both wideband sensors are about 30 inches from exhaust valves, at 2 and 10 o'clock, i just smoke tested my intake again and no leaks were found

  4. #4
    Senior Tuner kingtal0n's Avatar
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    Wideband sensor (typical in-car hobbyist level) needs to stay cool, at least less than 800*F iirc. It won't work properly at high temp or pressure.

    The instructions should say something about placing the sensor far from high temperature.

    make sure you've got a complete PCV system and also pressure tested the crankcase (1 or 2psi max) you should be able to blow into the fresh air vent and hold the air inside it more or less like a balloon. If the engine is forced induction you will also need a Supra PCV valve the chevrolet pcv valves will leak.

    If you turn on the O2 sensors and the fuel trims suddenly max out that is usually a sign of bad O2 sensor narrowband

  5. #5
    when you are saying pvc system testing with a bit of pressure you mean from the intake to the pcv valve right? because the crank case of and engine will not hold air for long since it can escape tru a lot of places, but yeah i could check my pcv valve since i have it in line with a catch can, just so it it cleaner, and yes my catch can is vacuum proof i just tested it today with a smoke machine under 5 psi, no smoke coming out of nowhere...

  6. #6
    and for the narrowband if you quickly look at my scan file you will see it is only ayt idle that my bank 2 maxes out in the negative, at cruising throttle it is close to matching my bank 1 but in negative instead of positive, thats what i am after, why is it in the negative

  7. #7
    Senior Tuner kingtal0n's Avatar
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    Quote Originally Posted by [email protected] View Post
    when you are saying pvc system testing with a bit of pressure you mean from the intake to the pcv valve right? because the crank case of and engine will not hold air for long since it can escape tru a lot of places, but yeah i could check my pcv valve since i have it in line with a catch can, just so it it cleaner, and yes my catch can is vacuum proof i just tested it today with a smoke machine under 5 psi, no smoke coming out of nowhere...
    the crankcase should only have 1 fresh air vent from behind the air filter, but before the turbo compressor. This is adequate for most setups up to 1000rwhp.

    The PCV valve is a check valve, so not technically a 'air vent' because air can flow OUT of the crankcase into the intake manifold but not the other way around. So if you blow into the fresh air vent, the crankcase pressure will rise and gradually bleed off into the intake manifold through the pcv valve, however this takes a while, it should hold pressure like a balloon for some time say 10 to 20 seconds at least. The size of the orifices is critical to each setup and their flow rates should be calculated for effective pcv during normal operation. The Desired pressure in wet sump applications of crankcase is approx 1-2" Hg or roughly 30" of water. You want 30"~ of H2O at all times idle/cruise/WOT and adjust the orifices to supply this pressure drop.

    A proper crankcase pressure test would have you block the pcv valve so it cannot flow to the intake, then blow 1-2psi into the fresh air vent.
    Those should be the only two entrances/exits to the crankcase during normal operation. The dipstick would serve as an additional potential leak source, and so will any gaskets or holes elsewhere, you need to find all those holes including the dip stick and seal them up so the crankcase will hold air.

    Then, you should perform an actual boost pressure test on the intake side. Re-enable the pcv valve so it works like normal, then pressurize the intake manifold and all associated turbo plumbing to beyond the boost pressure you actually use. For example if using 15psi of boost then a 20psi pressure test is typical. You should fill from the turbo inlet all the way to the intake manifold with that pressure. Then verify the pcv valve is not leaking (chevrolet pcv valve will leak, it needs a supra pcv valve in-line for forced induction). And fix any other leaks along the way.

    Just be sure the fresh air vent for crankcase feeds from/to the pre-turbo intake (behind the air filter, before the turbo compressor). And disconnect this fresh air tube during the intake manifold pressure test so you don't pressurize the crankcase which will blow out the oil seals.

    Here is a pressure test examples; First I show on the engine by itself, note the leaking pcv valve,
    then at the end of video we do a complete turbo->intercooler->intake manifold test.
    https://www.youtube.com/watch?v=rYZmZqn3-x0
    Last edited by kingtal0n; 07-10-2020 at 03:57 AM.

  8. #8
    Senior Tuner kingtal0n's Avatar
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    Quote Originally Posted by [email protected] View Post
    and for the narrowband if you quickly look at my scan file you will see it is only ayt idle that my bank 2 maxes out in the negative, at cruising throttle it is close to matching my bank 1 but in negative instead of positive, thats what i am after, why is it in the negative
    I cant view your log file but if you see a normal operation narrowband during cruise but a wandering, maxing voltage at idle, it could mean something like:
    1. fuel injector leak (if its going rich)
    2. exhaust leak (if its going lean)
    3. not staying hot enough (unlikely but could be a bad heater circuit for 3 and 4 wire sensors)

    probs one of those