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  • Low/static load dyno testing

    Has anybody here done it extensively? I it only did a little bit to get AFR's right, with the previous 7.8:1 engine.

    What I am wondering specifically is what kind of timing and fuel requirements you found ideal for power in these very low load areas used during lean cruise. Given a VG, and level of modification obviously yielding VE (eV) changes that need to be compensated for I can't expect a little variance here.

    For example: I run 50 degrees at lean cruise with an actual closed-loop AFR reading between 14.7-15.0 using my LM-1 (which is now working, but only until I step on the gas, then it flakes out again). What's nice about this running condition is the staggering gain I saw in fuel economy. I literally got 2mpg better fuel economy, up to an average of 28 from the previous 26 highway.

    What's not so nice is the transient enrichment; the next load column does not seem to take effect until the exhaust-measured AFR is already heading lean. This is regardless of what the TP setting is in that load column. This means I'm losing response from not getting that acceleration enrichment (or accel-pump-like action). I will also occasionally get a very slight miss. POT TPS systems are nice for situations like that. I wonder if there would be a way to incorporate it into the program using NisTune?

  • #2
    So you are saying that as soon as you hit the gas to speed up from a cruize the ecu doesnt know, (besides the increased air flow), because you are only able to run the "on/off" tps right?

    So other than extra air coming in, it doesnt understand that you just changed the throttle position correct? therefore has no way of adding that short burst of fuel to get it going(in a nice responsive manner anyways)?

    I dont know of an aftermarket system that uses a MAF AND a potentiometer TPS. HMMM. I wish I could be some help.
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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    • #3
      I believe the issue may lie in the distance of piping I have between turbo and IC. This means the voltage signal is slower to respond because the maf is slower to read the influx of air (for some reason, it could simply be a maf latency issue or an ECU speed issue).

      I have heard some AFC's have this ability? To add a TPS type "spike" on top of the regular curve when the tp changes suddenly?

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      • #4
        You cant dont do anything with the mulit-point tps from a auto?Or is that what a POT tps is?
        1986 Current build
        HX35/40 60mm wheel,480cc injectors,nistune, spearco 2-221,6 puck,walbro fp,solid cross and diff,jason motor mounts,poly everywhere else.

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        • #5
          I am so far behind you guys in this that I may be completely off the topic, but MS uses the TPS for accel enricment on top of MAP, and I know that there have been some that hacked MS to use an AFM. I know this doesn't help you, but at least I think there are those who have done TPS "spikes" on AFM systems. How to do it with NisTune I can't even begin to speculate.

          Wilson, I beleive the pot (potentiometer) TPS has a linear signal over the entire range of throttle. All Z31's were point type contact, and I don't think any points would be active in this light to moderate throttle off cruise situation.

          If I am completely off base or worthless here, ignore or delete me and move on !

          Jason

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          • #6
            perhaps the auto ecu uses it in it's calculations since it has it already for the auto shift/kickdown points

            remember the ecus have code that controls stuff besides the fuel and timing maps, whatever capabilities it has and whatever sensors it uses, the hardware and software are matched .... without someone fluent in assembler for the chip we can only guess

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            • #7
              is converting to a MAP system out of the question? That is one of the first mods that I'm going to make when i go standalone because it tends to be more responsive (especially in turbo cars with long pipes) and I'd like to rid myself of the restriction that is the MAF.
              Funny stories!

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              • #8
                homestar wrote: is converting to a MAP system out of the question? That is one of the first mods that I'm going to make when i go standalone because it tends to be more responsive (especially in turbo cars with long pipes) and I'd like to rid myself of the restriction that is the MAF.
                you're inviting someone to make an ass out of you....

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                • #9
                  [quote]G-E wrote:
                  Originally posted by homestar
                  is converting to a MAP system out of the question? That is one of the first mods that I'm going to make when i go standalone because it tends to be more responsive (especially in turbo cars with long pipes) and I'd like to rid myself of the restriction that is the MAF.
                  you're inviting someone to make an ass out of you....
                  Agreed.
                  Originally posted by Andrew84zx
                  tell her your car is so fast it will make her panties fly off
                  545 RWHP & 540 RWTQ

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                  • #10
                    homestar wrote: is converting to a MAP system out of the question? That is one of the first mods that I'm going to make when i go standalone because it tends to be more responsive (especially in turbo cars with long pipes) and I'd like to rid myself of the restriction that is the MAF.
                    *Quit driving like a v8 torqued pansy.
                    Learn to utilize the VG30 the way it was meant to.
                    Shift!

                    "At times I go to pass someone and notice a bog, but I'm like in 4th gear....blah,blah, blah.."

                    Restrictions of mass air?
                    hmm..tasty topic.
                    :P
                    I am here to help...

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