I have discussed this problem earlier but it has been a few months. My motor is all put back together and i am back to where i started from the begining. Engine cranks great and runs perfect for about 5 seconds then dies. I have not put a fuel pressure guage on the fuel rail but i don't think that is the problem. My pump is an MSD that delivers twice the flow of a stock pump. I really think it is the computer shutting something down. I have used tunercat to reprogram but am not sure i did it all correct (first time). Anybody in the phoenix area have experience? thanks
LT1 won't stay running (1 Viewer)
- Thread starter kenai
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
id start with the fuel pressure gauge, This is probably the biggest issue people have with any EFI install.. Put a gauge on it, and verify pressure, then move on from there..
I still contend your VATS thinks you are a theif. hot wire your fuel pump to 12v+ leave it run then fire the engine and see what happens. I assume you are running the msd pump off the gm fuel pump relay?
If the fuel pump produces enough pressure to start the engine, it should be good. I concur with Kirk that it the VATS.
- Thread starter
- #7
okay, i tried hot wiring the fuel pump. Same result. I thought this would happen because the fuel pump comes on for 2 seconds before i start it and it will stay on for 2 seconds after the engine dies. Does the VATS kill power to the coil?
What year and model is the ECU???
- Thread starter
- #9
it is all from a 94 vette. I used tuner cat but this has been my first time with such a program. Sometimes when i try and start it the engine will let out a hiss from the intake, like a little backfire. My thought is that i need to figure out everything the LT1 needs to run and then go back and recheck it all, especially electrical. Any thoughts or steps for me to follow would be greatly appreciated. thanks already!
Couple of other questions 1st. The ecu is also a 94 vette? So you are running a mass air sensor? Did you use a stock/factory wiring harness or and aftermarket no emissions equipment harness?
I am less familiar with the sequential/mass air ecu's, but they work off the same fundamentals. I would get on ebay and buy a 94 vette factory manual. it is 2 books you need book 1 i think.
I took a 95 engine and converted it to a 1992 vette wiring and ecu. I did this b/c I did not want the mass air sensor and they are easier to swap electrically.
Kirk
I am less familiar with the sequential/mass air ecu's, but they work off the same fundamentals. I would get on ebay and buy a 94 vette factory manual. it is 2 books you need book 1 i think.
I took a 95 engine and converted it to a 1992 vette wiring and ecu. I did this b/c I did not want the mass air sensor and they are easier to swap electrically.
Kirk
- Thread starter
- #11
Kirk,
Yes, PCM is from the vette.
I used the stock harness but stipped off the emission stuff. I (think) i deleted all necessary emission parts when reprogrammed. I removed the EGR from the engine and also the MASS air flow, i put the PCM on speed density. Do you have a completed reprogrammed file that i could give a shot on?
Yes, PCM is from the vette.
I used the stock harness but stipped off the emission stuff. I (think) i deleted all necessary emission parts when reprogrammed. I removed the EGR from the engine and also the MASS air flow, i put the PCM on speed density. Do you have a completed reprogrammed file that i could give a shot on?
I run the older ecu that has the actual PROM "chip". I has a emissions deleted version with no tranny etc etc burned for it. I did however have a similar problem like this before the chip arrived.
I suspect that you could have a grounding loop problem in the wiring harness. Those factory harnesses are a bear to de-smog. I bought a painless emissions free model.
- Thread starter
- #14
Just to give yall an update, i programmed the pcm with a 94/95 camaro definition file as recommended by tuner cat and now it runs! I guess the vette stuff is more tempermental.
However i am discouraged again because I am not getting any oil up on the right side bank!! WTF! there must be a clogged passage as I get oil on the left side. I Used plenty of assymbley lube and lucas stabalizer on the valve train so i don't think hurt anything but what are my options? This motor was purchased from a salvage yard, 40k but it may have sat a while i don't know. Is there any kind of hard detergent that i can use to break up a clog? thanks!
However i am discouraged again because I am not getting any oil up on the right side bank!! WTF! there must be a clogged passage as I get oil on the left side. I Used plenty of assymbley lube and lucas stabalizer on the valve train so i don't think hurt anything but what are my options? This motor was purchased from a salvage yard, 40k but it may have sat a while i don't know. Is there any kind of hard detergent that i can use to break up a clog? thanks!
Eskimo
SILVER Star
Glad ya got it running (and oiling)!
A friend is steering me towards a LT1, but the Opti-spark concerns me for off-road use.. Your thoughts?
Now that it's running... Would you still buy a harness vs. stripping down the factory one?
A friend is steering me towards a LT1, but the Opti-spark concerns me for off-road use.. Your thoughts?
Now that it's running... Would you still buy a harness vs. stripping down the factory one?
Waggoner5
SILVER Star
Nothing wrong with the later Optispark. The later engines had the waterproofing issues resolved. I love them and know many out there in Jeeps that work great. Stripping down the factory harness is easy to do, but aftermarket is easier to mount and to make look good.
My .02
My .02
Eskimo
SILVER Star
What years should I be looking for? The one in question is from an Impala SS..
For that matter, which is a better engine.. LT1 from the Impala, or a '97 Tahoe Vortec 5.7?