1993 z28 lt1 vats =, need help

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kelbystanley
Posts: 11
Joined: Sat Dec 01, 2012 6:59 am

1993 z28 lt1 vats =, need help

Post by kelbystanley »

how do i turn off vats? thought i had it but it didnt work?
:(
robertisaar
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Post by robertisaar »

how did you turn it off and what is happening?
kelbystanley
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Post by kelbystanley »

unchecked the set box on all vats boxes. it is turning over but will not crank. i cranked it with starter fluid but it dies quickly. everything else is working but it will not start.
robertisaar
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Post by robertisaar »

is there a believable BPW being displayed in the datastream just before/when cranking?
kelbystanley
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Post by kelbystanley »

not that i can tell. i have spark but no fuel. the injectors are not firing. i put the motor in a 1972 c10.
billgraves
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Location: Memphis, TN

Post by billgraves »

After you turned OFF the Enable VATS boxes, did you "Turn Off" the Trouble Code"? I Would also "Clear Codes" If you do not have Clear COdes, disconnect the Battery for a minute to reset the diag codes.

When diagnosing this I would use a test lamp or NOID LAMP on one of the fuel injector terminals to say No Injector pulse. (I would test for Battery power at the injector harness as well. Fuel PRessure?)

Just a few thoughts. Hope you can get this fixed.
kelbystanley
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Post by kelbystanley »

Disconnected the battery fro 2 days, I also have a noid light plugged in and do not get anything from any of the injectors ( tried them all). I have the 12 volts at the pink wires on all injectors and also have good fuel psi. for the life of me I can't figure out what is going on.
billgraves
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Location: Memphis, TN

No Start from your LT1

Post by billgraves »

OK. Now I would start at this point. Get a SCANTOOL that will read your data stream. Watch Engine RPM (Several eng rpm could be available within the data stream and could be sampled at different points in time
) SO LOOK AT ALL OF THE RPM reads and crank the engine. (I am taking it HAS spark as you indicated it will run with a shot of staarting fluid.) If you have NO ENGINE RPM indicated it COULD be the Low or Hi REsolution signal comming from teh ABITs system is not getting to the ECM. You need a service manual to properly diag this.
If the VATS is disabled the normal VATS stall will Crank, start up and run for 2 to 4 seconds then stall. If you have a NO START treat your system as a No Start. That is what I would do. (Even though you have sparkk, this does not indicate you have a RPM Pulse to the ECM.)
kelbystanley
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Post by kelbystanley »

i have spark at the coil but not the opti. and i also have no injector pulse. the puzzling part is before i changed the coil i had barely any spark there. thats why i changed it out. then i had no start so i changed out the opti. im starting to think the ecm may be bad.
billgraves
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Joined: Fri Oct 20, 2006 6:55 am
Location: Memphis, TN

Lack of spark?

Post by billgraves »

I would highly suggest you either borrow a GM Service Manualor buy the diagnostic section. If I remember right Howell EFI in Michigan sells a book (gives them with the purchase of a wiring harness) for 20 or so bucks. I think it will diagnose your 93LT1. I have seen this so many times. Someone starts to replace parts one by one and end up paying much more than just a few bucks for a book and one or two parts. This has played out for many years.
Libraries have SOME service manuals but I see where they have cut back due to $$$. Try these http://howellefi.com. I have one I just dug out. It is yellow and has Howell Enginee Developments, inc. Service Manual for Corvette, camaro, firebird. LT1 & TUNED PORT FUEL INJECTION and their address. It has the ABITs diag and no start REPRINTs from GM service manual. Worth the funds for you.

It has no spark at any of the spark plug wire ends? If this is the case and has spark at the ciol the rotor could be burned through. The ABIT system is fragile. I would replace the complete system and not one frm CHINA. Either a Delco or Delphi or GM only. IF you have a new rotor and cap, and have no spark at the plug wire ends with a Small gapped plug, then treat this as no spark.
I hope this helps and there are MANY things I can miss by not seeing, feeling, smelling or hearing your car and system.

If you purchase a ECM do yourself a favor and buy a delco or gm reman. I have seen TOOOOO Many others have a host pf other intermitant problems. It is not worth it $ wise to save $25 and have problems.
kelbystanley
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Joined: Sat Dec 01, 2012 6:59 am

Post by kelbystanley »

I have the chiltons and haynes mauals. I just can't figure out why im only getting .5 volts instead os 5 at the refernce points aand i have good voltage everywhere else.
billgraves
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Joined: Fri Oct 20, 2006 6:55 am
Location: Memphis, TN

Low VOlts

Post by billgraves »

Hello,
Low Voltage. I have run into a low voltage reading before. I learned early on to use a Quility Volt meter AND to ALWAYS sorce my GROUND TO THE BATTERY NEG TERMINAL. I saw a fellow tech measure ECM voltage at the ECM with the Ground of the DVOM connected to the ECM case on a GM. It read low. The problem was a loose GROUND terminal at the engine block. I measured almost battery voltage on the Ground terminal at the ECM. Tightened the ground bolt and the voltage went to 0.1.
I hope this helps ya. Good luck. Look at the AITS system very close.
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Six_Shooter
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Post by Six_Shooter »

IIRC, the PCM you are using is a flash type PCM, meaning it gets a new calibration flashed through the ALDL connector, and no way of actually emulating, unless you use a Road Runner from Moates.

Providing a PCM service number would help clear up any mystery.

After you uncheck the VATS boxes, did you flash the new calibration to the PCM? I've seen this simple step missed by even experienced tuners and cause frustration.
kelbystanley
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Joined: Sat Dec 01, 2012 6:59 am

Post by kelbystanley »

ecm no. 16159278
it is not a flash. i have to burn the chip with a burn 2 and install with an adapter into the ecm.
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