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tbi question

Discussion in 'The Garage' started by g_mo, Feb 7, 2005.

  1. g_mo

    g_mo 1/2 ton status

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    i got a tbi 305 with harness and ecu. planning on putting the tbi on my 350.
    i was wondering if the ecu will work with the 350. the 350 is around an 74-76 block. i know i'll need different heads. planning on using vortec heads. will i just need to change the prom in the ecu? will the 305 injectors provide enough fuel for the 350? the 350 motor has a small cam and is bored .030 over. the tbi setup is out of a late 80's firebird.

    thanks
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Only have experience with TPI, but the same should hold true...

    The 305 knock sensor is different than 350. Change it to correct. If there is a seperate ESC module with TBI (my TPI has it) that is also different between 305 and 350 and needs changed. If there isn't a seperate ESC module, you'll need the right PROM for the ECM.

    I'm sure 305 and 350 injectors are different, and I wouldn't attempt to run it like that. Could and probably will go lean on acceleration, and the system won't see it, and you can/will destroy your engine that way.
     
  3. eagle mark

    eagle mark 1/2 ton status

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    It will work! But not run well at all.

    Start with the correct injectors to the motor.

    If you have to pass emmisions you'll need all that stuff. If not loose the knock sensor, ESC and EGR. Yes you'll really need a new chip now but will run better.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    How does a properly tuned EFI engine run better without the ESC system?
     
  5. eagle mark

    eagle mark 1/2 ton status

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    The ESC works with the Knock sensor. The Knock Sensor is the problem (lots of times) it will send false signals and retard timing when not needed. Especailly when doing performance mods like cam and things that change RPM and power.

    Some light pinging does not hurt a motor. KNOCK does. If you can't hear a KNOCK keep the knock sensor and ESC.

    There's some other flaws there too like my 93 Caprice 9C1 packeage. It pulls great to about 4,000 rpm but then falls on it's face till 4,500 then shifts. It's been documented on some GM boards on others as well. The ESC/Knock sensor combination has been the culprit.

    Here, I cut and pasted this from the engineer at AFI.
    18. Answer: Do you use a knock sensor on your systems?

    We usually do not use a knock sensor but will upon request. The knock sensor is a device that is used in an attempt for the auto companies to ring out additional fuel economy (usually less than .3 mpg) and still allow for use of almost any fuel that a vehicle may see. The problem with knock sensors is that they can only detect a noise in the block, so any knock be it from lifters, drive chains, etc. will magnify itself as spark knock. Many knock sensor equipped engines falsely retard spark causing a lack of performance than accurately measure spark knock.

    Some newer engines use 2 very expensive knock sensors with highly sophisticated control algorithms. These systems still cannot discern engine noise from spark knock.

    Hope that helps
     
  6. Thunder

    Thunder 3/4 ton status

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    You will need 55lb hr injectors. 305s have 40 lb hr not enough to feed a 350.

    A chip from a 350 ECM. Unless you have a computer grind cam you will probabaly need a custom chip programed for the cam. And yes if you are going for performance have the knock sensor function deleted from the chip.
    Also should have an adjustable fuel pressure regulator so you can feed more fuel to it. The stock setting will be too low PSI for Vortecs and a cam.

    FYI you can get around the knock sensor power loss and still keep the knock sensor.. But you need a Scanner and an adjustable fuel pressure regulator. You use the scanner in real time mode to monitor the knock sensor counts. Then you have to make runs slowly increasing the FP and timing till you get the best performance without getting any knock counts. I run my 89 TBI at 5* advance and fuel at 14 psi. Get no knocks there and good performance. Pulls good all the way up to 5K
     
  7. g_mo

    g_mo 1/2 ton status

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    does anyone here burn chips? how much $?
     
  8. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    eagle mark does :cool1:
     
  9. eagle mark

    eagle mark 1/2 ton status

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    Actually I don't ! :D The boss does...

    They are guaranteed too! AFI get's A LOT of information first! Then they burn a chip. They also help diagnosing any problems and if you have a cable and a laptop you can use WinALDL (FREE) to record data, if it needs tuning AFI will burn another. $95.
     

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