I tried matching the ECU with the motor on my recent LT4 swap. I bought a LT4 ECU and put it in my Camaro hoping it would run. I thought I could have an issue with the transmission not working correctly since the ECU was out of a 6 speed car and my SS is an automatic car. I started the car. It actually sounded like it was running a little smoother,,,,,, for 5 seconds. Then the car just shut off. It is consistent. It will start fine, it runs for 5 seconds and then it acts like you turned off the key. Help. Any ideas? Thanks.

 

Get proper custom programming for what you have.

 

I have been trying to find someone in my area that can do custom tuning but so far, I have struck out on that. That is why I tried the ECU swap idea.

 

You could try a mail order tune like PCM4LESS I've used them in the past.

 

Thanks rooster, I'll look into that. It looks like your car is pretty similar to what mine will be, if I can work out the bugs. Does your LT4 top end include the heads, intake, etc? How does it run?

 

I sent PCM4LESS an email last night. So far no response.

 

You haven't provided enough information regarding the vehicle. For example, the LT4 was OBDII. What year vehicle did you switch to the OBDII PCM?

To elaborate, OBDI vehicles had a Theft Deterrent Module. But the OBDII PCMs, used a Body Control Module.

If you put the OBDII PCM for the LT4 engine in a vehicle that did NOT have a BCM matched to the key and you did NOT do the resistor jump trick, then the PCM will shut down the fuel pump relay. It will not set an "SES" light.

You could check to see what the fuel pressure does to confirm this.

 

The car is a 96 SS which is OBD II. But the "BCM and matching key" and the "resister jump trick" are new to me. I plead ignorance. I don't know what you are referring to.

BTW. I did hear from PCM4LESS and they are confident that they can help me. The response seemed very professional and they threw in enough technical info to convince me to give them a try.

 

Here is a little info on the resistor and just some good knowledge.
https://www.camaroz28.com/forums/lt1...w-wire-196578/
https://www.camaroz28.com/forums/lt1...-crank-364540/

 

The tuning needs to be right for the car and the engine, if you had addressed that from the start you would be enjoying the car instead of trying to figure out what is wrong.

 

Unfortunately the money just isn't laying around in piles so I get things when I can afford them. If I can make something I already have work, I am more than happy to do that. Just operating on a tight budget. For example, I just plucked some exhaust hangers out of U-Pull-It auto parts for $3.00 since the ones on my car were MIA when I bought the car. But as soon as I can save up a little extra $$ I am going to sent the ECU off and get it remapped since there is no one in this area that can do it properly.