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Old 03-20-2018, 10:59 PM   #1
novafrog
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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
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Old 03-21-2018, 08:37 AM   #2
Ghost's68
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Re: 1st start-up on swap

VATS removed in the computer?
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Old 03-21-2018, 09:05 AM   #3
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Re: 1st start-up on swap

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Originally Posted by Ghost's68 View Post
VATS removed in the computer?
lt1 wiring did the harness said they did
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72,2wd short bed cheyenne,350,350trans,air,tilt,tach,posi 373 gears
70 nova 5.3,350 trans
80 z28 350,350,trans,bought new
03 cat.
06 gmc swb ext cab
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Old 03-21-2018, 09:38 AM   #4
BR3W CITY
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Re: 1st start-up on swap

Vacuum leak? Fuel Pressure?
What codes is it throwing? give us something to work with.
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Old 03-21-2018, 10:27 AM   #5
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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.
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Old 03-21-2018, 01:56 PM   #6
racecougar
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Re: 1st start-up on swap

Why are you attempting to run it without the MAF and O2 sensors installed and connected?
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Old 03-21-2018, 06:02 PM   #7
novafrog
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Re: 1st start-up on swap

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Originally Posted by BR3W CITY View Post
Vacuum leak? Fuel Pressure?
What codes is it throwing? give us something to work with.
no codes,fuel pressure 58-60 lbs
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72,2wd short bed cheyenne,350,350trans,air,tilt,tach,posi 373 gears
70 nova 5.3,350 trans
80 z28 350,350,trans,bought new
03 cat.
06 gmc swb ext cab
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Old 03-21-2018, 06:09 PM   #8
novafrog
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Re: 1st start-up on swap

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Originally Posted by davepl View Post
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.
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
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72,2wd short bed cheyenne,350,350trans,air,tilt,tach,posi 373 gears
70 nova 5.3,350 trans
80 z28 350,350,trans,bought new
03 cat.
06 gmc swb ext cab
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Old 03-21-2018, 06:17 PM   #9
novafrog
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Re: 1st start-up on swap

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Originally Posted by racecougar View Post
Why are you attempting to run it without the MAF and O2 sensors installed and connected?
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
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72,2wd short bed cheyenne,350,350trans,air,tilt,tach,posi 373 gears
70 nova 5.3,350 trans
80 z28 350,350,trans,bought new
03 cat.
06 gmc swb ext cab
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Old 03-21-2018, 08:48 PM   #10
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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.
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