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Thread: VAFPR and tuning

  1. #16
    Fuel Injected! brian617's Avatar
    Join Date
    Apr 2013
    Quote Originally Posted by CDeeZ View Post
    What are the specs of your engine you're running this setup with? Care to share your tune in it's entirety or any portion? I'm glad to hear about another person who has made high pressures work with the TBI setup on a 7427 PCM, very encouraging to me. What injectors are you running? I have the stock 61 pounders in there, and if my math isn't wrong then my flow rate is 93.2.. (Old pressure 12, new pressure 28, old flow rate of injector 61 = new injector flow rate of 93).
    I think there are copys of my .bin floating around this site, I've shared it several times, I just don't have access to my .bin on this PC. Think all of my build specs are in my signature, except I'm running 305 injectors I had cleaned and flow tested @ 12 and 25 psi. Been to long ago to remember what they tested.
    89 K1500 Scottsdale 5.7L 5spd 3:42

    Build specs: 97 4 bolt main block 350ci, Eagle rotating assembly with flat tops and 4 valve reliefs, Dart 165cc/67cc Iron Eagle heads, Manely SS valves and springs 110lbs seat @1.7, GM Ram Jet cam 196/206 @.50 .431/.451, stock intake and throttle body, heads and intake gasket matched, Delco EP377 fuel pump @ 22 psi, 427 PCM.

  2. #17
    Fuel Injected!
    Join Date
    Feb 2013
    Euless, TX
    Quote Originally Posted by 1project2many View Post
    I have found that they really need to match at the points where the transition occurs between open and closed throttle. By the time I'm done tuning I usually end up making the open throttle cells match closed in most cells.
    The absolute first thing I do is make those tables match.

  3. #18
    Fuel Injected! CDeeZ's Avatar
    Join Date
    May 2012
    Quote Originally Posted by dave w View Post
    Usually, when I have an engine that is running rich EVERYWHERE, I change the injector flow. For example if the injector flow is 93 and the engine is running extremely rich, I would change the injector flow from 93 to 95, or maybe 97. Increasing the injector flow will cause the computer to Lower the Injector Base Pulse Width, causing the injectors to spay less fuel.

    I consider the injector flow as a course adjustment, and the VE table as a fine adjustment.

    Injector flow is like apples / oranges / bananas

    What the injector is rated to flow.
    What the injector is actually flowing.
    What the injector parameter is in the .bin.

    More often than not, All Three are different!

    dave w

    Well this couldn't be more true about apples to oranges to banannas. I ended up copying "Injector Offset VS Battery Voltage" and "BPW Multiplier VS Fuel Pump Voltage" from BMHK binary. I believe this bin was for a 454 that used the high pressure TBI system. Fast and RBob pointed me in that direction.

    Entering a Injector Flow Rate of 160 PPH gives me an idle pretty damn close to stoich, and this is without even touching the VE tables yet. That flow rate is nearly double what I had calculated so Dave is definitely right about the apples to oranges to bananas.

    Makes me wonder why my original calculations using that calculator on witchhunter were so far off. Perhaps it is because the Walbro 255 is just a slight bit overkill for this application? I had it laying around so I tossed it in there.

  4. #19
    Fuel Injected! CDeeZ's Avatar
    Join Date
    May 2012
    I think the 7427 PCM I had in there previously was jacked, as I mentioned in another thread about the injectors pulsing even when the engine had been off for a while. Stabbed another 7427 in there tonight.

    I have been dialing in the min air rate as best I can right now and the thing is holding a good idle and rips clean pretty high in RPM in the garage for the first time since dropping in the marine high pressure regulator spring. It's idling around 14ish AFR. I ended up starting with another base copy of the 350 TBI 4L80 based tune I found and dumping in the injector parameters like mentioned above and upping the flow rate till it held a good idle.

    Thought I had a problem with the $0E fan code that I entered so I redid that also. Found out that the 20+ year old relay I stole from a Ford Explorer to control the Taurus fan finally rusted itself inoperable. (Confirmed by cutting the relay open).

    Thanks very much everyone.
    Last edited by CDeeZ; 01-12-2019 at 12:35 AM.

  5. #20
    Fuel Injected! Terminal_Crazy's Avatar
    Join Date
    Oct 2015
    Lancashire England
    Quote Originally Posted by Fast355 View Post
    I usually disable BLM and tune off the integrator alone. History average off the Integrator with the BLM disabled is a quicker way to tune than it is off BLM.
    Hi, can you explain that?
    Is that an average of the integrator values for each VE cell

    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  6. #21
    Fuel Injected! CDeeZ's Avatar
    Join Date
    May 2012
    I think what he is saying is he prefers to use the INT (short term trim) as it is a more recent reflection of fueling corrections vs the longer term fueling corrections that is BLM.

    I believe the INT is what your NBO2 is seeing right now whereas your BLM is averaged over time from the INT values.

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