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Thread: Fuel cut under full throttle

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    Fuel cut under full throttle

    I could use some help. Any ideas are welcomed. I'm at a loss. My car has a mean fuel cut feeling around 6500rpm, will pull clean through if I dial the boost back from 23psi to 18 . I've exhausted my ideas what could be wrong. Evo scan logs don't really tell anything significant. My suspicions is the tune or faulty injectors but logs don't show lean. If anyone wants to see a log I've got a few. I'm using the translator are the GM sensor to cut the signal in half and then have changed the loads in Chrome to compensate for this. Is there sub setting that might mess with the injectors for boost coming on too quickly?

    Setup: 1993 stealth
    New forged motor with compression just checked at 500 miles. (165psi all cylinders)
    Td05 16g and 9 blade turbines.
    1200cc Delphi injectors
    Walbro 450
    Boost reference regulator set 43psi and holds 64 under 23psi boost.
    Kennybell boost a pump
    Jesters and chrome
    Gen2 translator zeroed out and AFR traking disabled.
    Msd wires (checked continuity and no damage)
    Just installed ngk at .018 gap
    HKS DLI.
    Stock coils hot wired. Just swapped coils to confirm they weren't the problem
    "If there must be trouble, let it be in my day, that my child may have peace."

    Thomas Paine

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    Have you tried not using the MAFT to cut the signal in half and use chrome to do the entire injector and load calculation?

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    I had someone say to look at the injectors duty cycle and it drops even though the throttle is still floored. So somewhere the ecu is being told to drop it. I still don't know where to look through in the tune.

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    anyonebutme , I haven't tried that. I was at one point running it that way and it worked fine before I went TD05.
    Last edited by notimaginative; 08-05-2019 at 09:35 PM.

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    If you lie to the ECU like piggybacks do, and try to run too large a correction, the ECU can not believe the sensor input and decide to ignore it or trip protections. I really suggest zeroing out the MAFT and do all the tuning in the ECU. To test if that's happening here, look at what the airflow Hz is doing during fuel cut. Is it dropping out or doing weird things?

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    I've already pulled out an unaltered rom and started changing just the necessities for injectors. The car is smoother in the low end but it will take some driving and tuning before I feel safe to push it up to the same power level the problem was at. Thanks for the suggestion

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    Forum User Not Verified Feedback Score 2 (100%) RealMcCoy's Avatar
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    You are hitting fuel cut... The ECU thinks you are topping out the injectors. It's 100% a tune issue. You got any logs you can post? What are your MAFT settings? is it blow through or draw through MAF?

    I also prefer to do my tuning in the ECU... Many will disagree, but that's my preference. I would even go as far as hang a stock airflow sensor on it, tune the injector size and latency in, and then hook up the MAFT and tune it to duplicate the stock sensor.


    Real Performance Automotive (541)816-4500 www.FB.com/RealPerformanceAuto

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    RealMcCoy, I sent you my files. I'm not really sure what's the best way forward from where the car is right now. I can stick with starting over but then I will run the risk of find the limits and having to retune again. So I'd like to make the tune work that has the translator cutting the signal.

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    Forum User Not Verified Feedback Score 2 (100%) RealMcCoy's Avatar
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    Been looking over the ROM you sent me a bit... Haven't had a ton of time to put into it, and I'm not sure I have any answers as to what could be going on yet, but I do know a couple of things... Someone did a bunch of tuning on this ROM, and your thinking the tuning is being done in the MAFT is incorrect. The injector size is set to 1194 in this ROM. I also know I was incorrect in my assumption you were hitting fuel cut... Doing the math from the log you sent, you are only at about 51% IDC. The fuel cut target is set at 320 load in the ROM, with the target load being set at 159% (and it never went over that in the log) so there is really no way it's getting anywhere near fuel cut...

    I'll look it over a bit more when I get a chance... More questions than answers right now.

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