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Thread: REALLY Bad Fuel Mileage

  1. #21

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    Quote Originally Posted by Danny Cabral View Post
    Yes, but then he still might have magnetic pickup (RPM signal) problems. Maybe not, so it might be worth trying first.
    Unlike the MSD, the HEI is actually designed to trigger an (albeit different) EFI system, so the failure rate seems to be lower. Given that a few hundred bucks are on the line, it's definitely worth a try.

  2. #22
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    Good point, I agree.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. Default

    Quote Originally Posted by Dr_Grip View Post
    You can lockout the GM large cap HEI advance mechanism and use it for timing control. Will save you big $$$.
    I kind of figured there might be a way to do this. I did it once before using an HEI module to trigger an Accel CD box. Could this go the other way and have the Sniper control the HEI module & ignition?

  4. #24

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    Nope, you remove the module and directly hookup the three wires of the Sniper to the distributor instead: The gray wire from the coil driver module replaces pin "C" of the module. The purple & green crank signal wires replace pins W & G of the module. (Sadly, cable colors are not standardized in aftermarket HEI distributors, so you'll have to try the polarity.) Pin B is the power supply for the module, so it's not needed any longer.

    You can do this either by purchasing adapters or by soldering. And of course, you'll have to disable mechanical & vacuum advance. Depending on the model of distributor, it's either is prepared for this or will need a spot weld and a screw to lock them up.

  5. Default

    Digging this thread back up. Now that the thing is more or less tuned, my plan is (like this thread said) to tune for MPG. I have already taken the AE table values down quite a bit. I had an idle surge that I cleaned up by changing the AE vs TPS RoC Blanking (per Danny) back to 15.0. I may see how it acts with this number around 10.0. Any other suggestions for MPG? I would like to see this engine in the 20 MPG highway range if possible...operative word being IF.

  6. #26
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    Read post #2, I added an "AFR & Timing Information" link.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  7. Default

    So, based on the example from your engine, I took the base calibration that I posted earlier and changed the Target AFRs a bit, to lean them out some. I know to look for detonation and enrich some if I note it. Now, I did take the Offset tables and lean them out a bit too, in the normal engine operating temp ranges. I have also moved the AE vs TPS RoC Blanking value to 12 for a little better throttle response. Does this sound reasonable? I have attached the .sniper file here in a ZIP.
    Attached Files Attached Files

  8. #28
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    Quote Originally Posted by FrozenCajun View Post
    Now, I did take the Offset tables and lean them out a bit too, in the normal engine operating temp ranges.
    Usually, the Coolant Temperature Enrichment % & A/F Ratio Offset tables are too rich in the base calibrations. There's some related information here:
    http://forums.holley.com/showthread....6254#post36254 (Good Starting Advice Thread - Especially posts #2, #4 & #6.)

    I have also moved the AE vs TPS RoC Blanking value to 12 for a little better throttle response. Does this sound reasonable?
    Yes, just ensure the ECU isn't switching in & out of Closed Loop.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  9. Default

    Quote Originally Posted by Danny Cabral View Post
    Usually, the Coolant Temperature Enrichment % & A/F Ratio Offset tables are too rich in the base calibrations. There's some related information here:
    http://forums.holley.com/showthread....6254#post36254 (Good Starting Advice Thread - Especially posts #2, #4 & #6.)
    Sounds like this is gonna be an exercise in trial & error. Sure wish I had a decent laptop to carry around with me in the rig for this.

    Quote Originally Posted by Danny Cabral View Post
    Yes, just ensure the ECU isn't switching in & out of Closed Loop.
    Good advice. Thanks. I hadn't thought to look at this. Maybe I should look at it in the most recent datalogs I have.

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