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Thread: No start TBI/TPI truck

  1. #1
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    No start TBI/TPI truck

    I did a TBI to TPI conversion on a 95 5.7 this summer. I can crank, but no start. I have great spark to all plugs as well as fuel to each cyl. PSI is 45 and none of the injectors are stuck open. Ill pull the plugs after a 3 second crank and the plugs are dripping in gas. This is after I dry out the cylinders each run.
    I have checked out all that I can think of, and the last I need looked at is the BIN/XDF. I used the one off this website and made the MPFI modifications required in the doc and spreadsheet provided by dave. I also removed the resistors and added the jumper. Attached is what I burned and have in a G2 from moates.
    I tried to upload the Tunerpro log of what I changed, but it would not allow the attachment. Below is the contents.

    Edit Log for ready to burn.bin created by TunerPro.
    ************************************************** ************************
    08/11/2017 17:51:07 Flag: Synchronous Fuel At Idle changed from Set to Not Set..
    08/11/2017 17:51:16 Flag: CPI/PFI Mode changed from Not Set to Set..
    08/11/2017 17:51:59 Flag: Crank Fuel All Injectors Each DRP changed from Not Set to Set..
    08/11/2017 17:52:22 Flag: Use Async Short BPW Offset vs. BPW Table changed from Not Set to Set..
    08/11/2017 18:01:30 Scalar: Minimum Async to Sync BPW changed from 701.9 uSec. (0x002E) to 1495.4 uSec. (0x0062).
    08/11/2017 18:01:50 Scalar: Minimum Sync to Async BPW changed from 503.5 uSec. (0x0021) to 1297.0 uSec. (0x0055).
    08/11/2017 18:02:18 Scalar: Async to Sync Fuel MAP Threshold changed from 81.2 Kpa (0xC0) to 104.4 Kpa (0xFF).
    08/11/2017 18:02:36 Scalar: Async to Sync Fuel RPM Threshold changed from 2000 RPM (0x50) to 6375 RPM (0xFF).
    08/11/2017 18:03:08 Scalar: Sync to Async Fuel MAP Threshold changed from 87.1 Kpa (0xD0) to 104.4 Kpa (0xFF).
    08/11/2017 18:03:39 Scalar: Sync to Async Fuel RPM Threshold changed from 2100 RPM (0x54) to 6350 RPM (0xFE).
    08/11/2017 18:04:09 Scalar: Maximum Async BPW changed from 12.0 msec. (0x0312) to 6.1 msec. (0x0190).
    08/11/2017 18:04:26 Scalar: Minimum Async BPW changed from 503.5 uSec. (0x0021) to 1907.3 uSec. (0x007D).
    08/11/2017 18:05:13 Scalar: Minimum Synchronous BPW changed from 396.7 uSec. (0x001A) to 1297.0 uSec. (0x0055).
    08/11/2017 18:05:26 Scalar: Minimum Synchronous BPW Allowed changed from 396.7 uSec. (0x001A) to 1693.7 uSec. (0x006F).
    08/11/2017 18:05:51 Scalar: Async Short BPW Offset Bias changed from 396.7 uSec. (0x001A) to 30.5 uSec. (0x0002).
    08/11/2017 18:07:31 Scalar: Injector Flow Rate (MPFI lb/hr) changed from 30.5 lb/hr (0x189C) to 22.0 lb/hr (0x11BE).
    08/11/2017 18:10:42 Scalar: Injector Flow Rate (MPFI lb/hr) changed from 22.0 lb/hr (0x11BE) to 21.0 lb/hr (0x10EF).
    08/11/2017 18:10:51 Scalar: Injector Flow Rate (MPFI lb/hr) changed from 21.0 lb/hr (0x10EF) to 22.0 lb/hr (0x11BE).
    08/11/2017 18:18:05 Table: Async Short BPW Offset vs. BPW changed.
    08/11/2017 18:30:20 Scalar: Temperature for EGR On changed from 74.8 C (0x99) to 151.3 C (0xFF).
    08/11/2017 18:31:44 Scalar: RPM for EGR On changed from 800 RPM (0x20) to 6375 RPM (0xFF).
    08/11/2017 18:31:58 Scalar: RPM for EGR On changed from 6375 RPM (0xFF) to 800 RPM (0x20).
    08/11/2017 18:32:53 Scalar: Minimum Speed for EGR changed from 0.0 MPH (0x00) to 255.0 MPH (0xFF).
    08/12/2017 11:33:05 Table: Injector Offset vs. Battery Voltage changed.
    Attached Files Attached Files

    1992 Camaro Z28 5.7
    1995 Silverado 5.7 TPI

  2. #2
    Super Moderator dave w's Avatar
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    I'm wondering if the distributor is correctly aligned? I would pull the fuel pump fuse and crank the engine with a timing light connected to #1 cylinder to see if the timing is set to ZERO. Maybe the distributor is set to #1 cylinder Top Dead Center on the Exhaust stroke instead of #1 cylinder set to Top Dead Center of the Compression stroke?

    dave w

  3. #3
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    I had thought about this as well. But rarely does the timing light light up on any spark plug wire. It does every time on the short coil wire though. The spark tester gives me spark on the spark plug wires also.
    While cranking, the battery voltage drops from 12 volts to 11, so it seems like a good battery.
    Also, the rotor turns, made sure of that.

    1992 Camaro Z28 5.7
    1995 Silverado 5.7 TPI

  4. #4
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    If you have a stock TBI 350 memcal try staring it on the stock Memcal. My old G20 wouls start and run on a stock TBI memcal.

  5. #5
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    I have already tried the stock computer.
    I took the distributor back out. With the timing mark at 0, the rotor is pointing at cyl 3. It was not this way before first crank with the TPI intake on roughly a few weeks ago.
    I have a new distributor i bought a while back and it happens to line up the same.

    1992 Camaro Z28 5.7
    1995 Silverado 5.7 TPI

  6. #6
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    If you have balancer at 0 and it points to #3 it is wrong. You need to confirm it is on compression #1 with balancer at 0 and then install so it points to #1. You said it wasn't that way when you set it up, the only way it could change is either something broke or the distributor has been allowed to rotate. One thing you could try, you said 3 sec of cranking makes plugs wet, you could crank maybe 2 seconds, then pull the injector fuse, put throttle maybe half and crank. If the timing was correct it should fire and run for a short time. But it sounds like ignition timing is the problem.
    6395, BHDF, 7.4 BBC lightly modded now 6395 BMHM back to BHDF

  7. #7
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    It may have pointed to 3 before back when I had to take the intake off to clean the EGR ports out. Either way, does it not hurt to just move the distrib housing to compensate? Thats what I did then. This time, I tried with no luck.
    I still cannot understand why my timing light flashes on the coil wire, but not on any spark plug wire. What is it from the distributor and rotor thats causing so much resistance that it cant even light up a gun? Or is it normal for a gun to not light up on only battery power?

    1992 Camaro Z28 5.7
    1995 Silverado 5.7 TPI

  8. #8
    Fuel Injected!
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    Did you plug a spark plug into a wire and lay it on the engine and see if it sparked?

  9. #9
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    I did and it had good spark. Today I also took the fuel rail off over to the bench and hooked my injector tester up to each one, and they all opened up and flowed fine.
    I put it all back together a few hours ago, sprayed carb cleaner in the cylinders, left the fuel pump unplugged and got ignition for a quick second.
    So I think its possible there is actually a fuel issue instead.

    1992 Camaro Z28 5.7
    1995 Silverado 5.7 TPI

  10. #10
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    If the plugs are drenched and won't fire you won't get the timing light triggering

  11. #11
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    It's starting up now. There may be some broken wires somewhere to the injectors. At any rate, it started up immediately but then also quickly made its way up up and away to 2000rpm before I killed it. A zip file, inside a CSV of those 5 seconds is what I captured. I dont know how much help that is though.
    I tried this a couple of more times and it acted the same. I then swapped in the old TBI ECM, and it also took off, but stopped at about 1500.
    For what it's worth, the timing connector is disconnected.
    Attached Files Attached Files

    1992 Camaro Z28 5.7
    1995 Silverado 5.7 TPI

  12. #12
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    Sounds like you have your IAC wiring messed up somewhere or you have a large vacuum leak.

  13. #13
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    If there is a 500rpm difference between TBI and MPFI chips, then there must be an issue in programming as well?
    I have an ebay adaptor for the IAC wiring. It just converts the TBI connector to the LT1/LS1 style controller. Is this going to be an issue?

    1992 Camaro Z28 5.7
    1995 Silverado 5.7 TPI

  14. #14
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    Nevermind - my euless bro was correct, there were 2 issues - vacuum at the back plenum, and i forgot about how the LT1 throttle body IAC passages sit flat to the TPI plenum and have to be cut to fit. So I fixed both and it idles now. The TBI ecu shutters somewhat, and the MPFI ecu with mods runs smoother. I only ran it long enough to check timing which was right on, and it ran about 800rpm.
    When i reached over and plugged the timing connector back in, it wouldnt start back up (no injector fire). Then i moved the ecu around and suddenly was good. what are the odds that both banks of injectors are now getting power because of jiggling the harness around.

    1992 Camaro Z28 5.7
    1995 Silverado 5.7 TPI

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