LT1 runs 2 sec then dies. Engine Swap.
05-26-2017, 10:41 PM
#1
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Join Date: Feb 2011
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LT1 runs 2 sec then dies. Engine Swap.
What I'm working on. 95 Buick roadmaster lt1 in a project. Using stock "tuned" ECM and wired up my own relays and fuse blocks. Donor car did have an issue of not starting once, let everything cool down and it came back to life. I'm using a fuel cell and inline walbro pump. I changed the opti as well with a brand new unit.
I got everything wired up, all electronics work on start. Fuel pump primes when key is on, etc. I tried starting it before I had set up tunercat . Started 2 secs then died. I figured VATS. Today I took out VATS and exact same problem. I have NOT verified proper fuel pressure nor checked injector pulse with a noid light.
I will check the aforementioned FP and Injectors tomorrow, but was just wondering if anyone had a good idea upfront. VATS not actually disabled? I flashed it then read it and the bin claims to have F+B and Y VATS disabled.
I got everything wired up, all electronics work on start. Fuel pump primes when key is on, etc. I tried starting it before I had set up tunercat . Started 2 secs then died. I figured VATS. Today I took out VATS and exact same problem. I have NOT verified proper fuel pressure nor checked injector pulse with a noid light.
I will check the aforementioned FP and Injectors tomorrow, but was just wondering if anyone had a good idea upfront. VATS not actually disabled? I flashed it then read it and the bin claims to have F+B and Y VATS disabled.
05-26-2017, 11:50 PM
#2
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Re: LT1 runs 2 sec then dies. Engine Swap.
How did you "take out VATS".... programming, resistor across pellet reader wires, fuel enable frequency simulator? Do you have DTC 46?
05-27-2017, 01:34 AM
#3
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Re: LT1 runs 2 sec then dies. Engine Swap.
sorry, assumed the tunercat mention would make that obvious but I know some people don't get it and rip parts out. I took it out with tunercat. just unchecked the checkboxs and reloaded it. Verified it took by rereading the PCM after flash. side note, i appear to have a B rev.
I also disabled checking VATS but maybe I should enable that DTC and see if it pops? Will it show up if I disabled it in the PCM or only if it is looking for the VATS signal?
I also disabled checking VATS but maybe I should enable that DTC and see if it pops? Will it show up if I disabled it in the PCM or only if it is looking for the VATS signal?
Last edited by 88LT1-TA; 05-27-2017 at 01:37 AM.
05-27-2017, 02:19 PM
#5
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Re: LT1 runs 2 sec then dies. Engine Swap.
ok. Noid light confirms I have injector pulse on initial start then goes away once it fires up. I do not have any DTC's besides coolant temp low, that was unplugged. Hooked it back up and reads ambient temp. Perhaps the one issue I had previously was a failing ECM?
I hooked up to freescan and all seems normal except the target idle is set at 3800. I checked IAC rpm vs coolant temp and all seems normal.
I hooked up to freescan and all seems normal except the target idle is set at 3800. I checked IAC rpm vs coolant temp and all seems normal.
05-28-2017, 01:25 PM
#6
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Re: LT1 runs 2 sec then dies. Engine Swap.
Pulled VATS module out of the donor car. Wired it up with a resistor and attached an led to the security light. Light comes on for 3 sec then goes out. Wired the blue wire to the PCM, same issue.
On second look the noid light is lighting up. The first pulse is very bright, the ones after that are dim, just barely making anything.
On second look the noid light is lighting up. The first pulse is very bright, the ones after that are dim, just barely making anything.