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Thread: VT 5ltr race car wiring

  1. #1
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    VT 5ltr race car wiring

    Hey all, I'm stripping out my vt to race car spec. I bought a vt 5ltr chip from commodoregear off ebay that has vats removed. I have stripped out all the unnecessary wiring and installed the chip. I have relocated the battery to the boot and wired up the starter and alternator correctly back to the original engine bay fuse box. I have installed an igntion switch and push button stater

    The ignition switch is connected to the pink/black wire which powers the engine control relay and the fuel pump. It also powers the push button starter. The push button starter is connected to the red/white wire to the start relay

    When I turn on the ignition the fuel pump primes for a second then turns off, I push the start button and nothing happens although the wire is pushing 12.5volts to start relay. So I tried removing the start relay and bridged the main wires and the engine started but won't keep running

    I tested spark and there is plenty the and continues to spark as the engine is turned over so that is working fine. I then put a test light across and injector plug and nothing

    So my questions are

    1. Could the chip be faulty or not have vats removed as the engine doesn't continue to run?
    2. It seems like the pcm isn't grounding the start relay (grey wire to pcm feom relay)
    3. Am I missing a wire somewhere to ground the start relay????
    Pics are of the pcm harness plugs showing wires that were discarded and of ignition wire (pink/black) and start wire (red/white)

    Please help
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  2. #2
    Registered User gtrboyy's Avatar
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    Checked for any fault codes? Blown fuses?

    Charge wire & cel wire still connected up to globes?

    Hot wire f/pump to see if it runs...had to use tachiometric relay to make it run in torrie.

    It had vats off & repeatedly blew fuse for maf untill just had power wire no relay.


    I use peeps on pcmhacking forum or ace performance tuning(facebook) for delco stuff.
    Commodores have so much wiring easier to just simplify that shit & treat it like a conversion with seperate relays etc
    an easy fix is get a mate to drive in front of you at 60 then 80 then 100 and mark in on your speedo with some liquid paper.

  3. #3
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    That's what I've basically done. With the help of wiring diagrams, I removed all the unnecessary wiring, abs, air con, air bags, bcm etc and have just left the basics like wipers, headlights, hazard indicators, rear window demister. As can be seen in the pics, pcm and engine bay is pretty much untouched. The ignition and fuel pump is working fine

    Sent from my SM-N950F using Tapatalk
    Last edited by Hqheath; 20-01-19 at 04:26 PM.

  4. #4
    Defective Faux Forg's Avatar
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    Is the chip you bought to suit an auto or a manual? In an auto the PCM grounds the start relay when it knows the car is in park or neutral. Not sure how a manual PCM switches on startup
    Quote Originally Posted by Marlin
    Chickens will slip under water in the cover of darkness like a seal team and FUCK YOU UP.

  5. #5
    arboreal bukkake briney's Avatar
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    often when there's a chip burning fuckup the fuel pump and possibly engine cooling fan will run continuously. also, as pointed out above, there's likely a wire which needs grounding for a manual car. that or just ground the relay directly?
    Quote Originally Posted by Skompa View Post
    The throttle linkages jammed on the CDs in my old Triumph 2000 and stuck it at WOT.

    I didn't realise for about 15 mins as it never broke the speed limit.

  6. #6
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    Thanks for the replies. It's a manual chip. I have a replacement on the way to try. Apparently the pcm should ground the relay

  7. #7
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    Replacement memcal arrived today. Fired up first go with push button starter and ran like a treat!

    Cheers guys

  8. #8
    Registered User gtrboyy's Avatar
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    Vats/security fault should have come up when checking codes & dash security light would stay on.
    an easy fix is get a mate to drive in front of you at 60 then 80 then 100 and mark in on your speedo with some liquid paper.

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