My car OBDI & OBDII Help Maj. Problems
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Registered User
Joined: Dec 2002
Posts: 116
From: Birmingham, Alabama
My car OBDI & OBDII Help Maj. Problems
Wow where do I start. I will start from the begining
I had a Lt1 383 built about 4-5 months ago. I have not gotten it dyno tuned yet, but I got pcmforless ObdI programing done. When I got this done I told him to program it for heads that I didn't end up putting on. So it was running really rich. To fix this problem I planned to take it to the local dyno. The owner told me to get a fuel pressure regulator to help tune it faster. So I did. A local shop put it on today. They tuned it to 45psi which is what they said was stock. black smoke poored into the shop. That is how rich it was running at 45psi. They said that they kepted turning it down trying to get the black smoke to stop. It stopped at 15psi! They said that they had to move it back up to 35psi because 15 was not going to work but that is not normal. They have no idea why it is running like this! they tried to scan my computer and my computer would not talk to theres. When they tried to scan my computer they used OBDII because that is the port that hooked up to the scanner, but I have a vented Opti, 2 o2 sensors, and other OBDI parts. So they don't know what is going on. So my 383 with .556 .576 camed car is running rich at 35psi! NOT Normal! Plus My computer seems to be both OBDi and 2 . They said that obd1 and obd2 have different plug in ports and if obd2 fit in there that is what mine is. That is the least of my worries because my car is running rich at 35psi! I am getting 4.77 miles to the gallon!
Help me! what could this be. Is it the air temp control sensor. because I know when they die the computer is told it is -280* outside and my computer could be trying to compesate for this but then why is they pressure so low?
I had a Lt1 383 built about 4-5 months ago. I have not gotten it dyno tuned yet, but I got pcmforless ObdI programing done. When I got this done I told him to program it for heads that I didn't end up putting on. So it was running really rich. To fix this problem I planned to take it to the local dyno. The owner told me to get a fuel pressure regulator to help tune it faster. So I did. A local shop put it on today. They tuned it to 45psi which is what they said was stock. black smoke poored into the shop. That is how rich it was running at 45psi. They said that they kepted turning it down trying to get the black smoke to stop. It stopped at 15psi! They said that they had to move it back up to 35psi because 15 was not going to work but that is not normal. They have no idea why it is running like this! they tried to scan my computer and my computer would not talk to theres. When they tried to scan my computer they used OBDII because that is the port that hooked up to the scanner, but I have a vented Opti, 2 o2 sensors, and other OBDI parts. So they don't know what is going on. So my 383 with .556 .576 camed car is running rich at 35psi! NOT Normal! Plus My computer seems to be both OBDi and 2 . They said that obd1 and obd2 have different plug in ports and if obd2 fit in there that is what mine is. That is the least of my worries because my car is running rich at 35psi! I am getting 4.77 miles to the gallon!
Help me! what could this be. Is it the air temp control sensor. because I know when they die the computer is told it is -280* outside and my computer could be trying to compesate for this but then why is they pressure so low?
Registered User
Joined: Feb 2002
Posts: 1,534
From: Lousiana
The shop doesn't know enough about how LT1 programming works. If you decrease fuel pressure then the pcm will make the injectors spray longer and vic verse. So you are chasing yourself. Put the pressure back to stock and call your pcm tuner for a new tune or go to a shop that does REAL dyno tuning for LT1's. It will be cheaper and alot easier in the long run.
Jeff D.
Jeff D.
Last edited by PoorMan; Jan 8, 2004 at 08:36 PM.
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