1st start-up on swap
 

will start then die, will not idol for longer than 10-15 sec. but if I rev it up, say 2500-3000 rpm's runs like a top, motor just setting in truck, no 02 or maf sensors hook up,2000 5.3 thanks for any help

Re: 1st start-up on swap
 

VATS removed in the computer?

Re: 1st start-up on swap
 

lt1 wiring did the harness said they did

Re: 1st start-up on swap
 

Vacuum leak? Fuel Pressure?
What codes is it throwing? give us something to work with.

Re: 1st start-up on swap
 

Does it run better without the MAF connected? If so, that'd indicate that your measured and actual air amounts are different. That could be air leaks or MAF placement if so.

Re: 1st start-up on swap
 

Why are you attempting to run it without the MAF and O2 sensors installed and connected?

Re: 1st start-up on swap
 

no codes,fuel pressure 58-60 lbs

Re: 1st start-up on swap
 

maf was on a long tube took it off and put it up to tb and tape it up good,still start and die but give it a little fuel and let off it would idol everytime I would start it I would have give a little fuel hen let off before it will idol

Re: 1st start-up on swap
 

motor is just sitting in truck,with core support and grill off wanting to make sure everything is ok before I put it back together, exhaust don't have 02 sensors in yet

Re: 1st start-up on swap
 

I have a very hard time believing there are no DTC's with the MAF and O2's disconnected. I'd recommend finishing the installation before attempting to run the engine any further. Without the MAF and O2's, the EEC has no reference to calculate load and determine appropriate fueling.