No Injector pulses
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Teching In
Joined: Mar 2017
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No Injector pulses I have read many of the threads about no injector pulses, seems like some have similar issues and some are totally opposite. Mine seems to be one of those that is different than others so here is what I have and whats going on.
2001 GMC Sierra, had a 5.3L now a stroked 6.0L to a 408CID
GM performance Heads
Lunati Hydraulic roller cam and lifters, Lunati roller rockers.
Fabricated intake with 102MM throttle body with 42LB injectors.
The computer was removed and sent in to have certain items removed, these include the EGR, rear O2 sesors,
My son forgot to have them remove the anti theft and top speed but as of now all I want is to get this thing running and to idle without shutting off immediately. Yes it shuts off.
This is what is going on:
(No injector pulses) I have constant power to the injectors, I have checked with a noid light. I have spark and fuel pressure, I know this because I can keep spraying with eether and it will run until I stop spraying. I know I have fuel pressure because I have a fuel pressure regulator with a gauge attached to the fuel rail, I have 60 Lbs..
I have checked and I do not have any codes or check engine light. I have done the 30 minute reset to no avail.
The cam and crank sensors are new along with a new battery.
I was thinking it might be the Antitheft system BUT, the security light does not stay on or blink when the key is turned to the on position. I have checked all the grounds.
Any ideas or help would be greatly appreciated. Thanks
2001 GMC Sierra, had a 5.3L now a stroked 6.0L to a 408CID
GM performance Heads
Lunati Hydraulic roller cam and lifters, Lunati roller rockers.
Fabricated intake with 102MM throttle body with 42LB injectors.
The computer was removed and sent in to have certain items removed, these include the EGR, rear O2 sesors,
My son forgot to have them remove the anti theft and top speed but as of now all I want is to get this thing running and to idle without shutting off immediately. Yes it shuts off.
This is what is going on:
(No injector pulses) I have constant power to the injectors, I have checked with a noid light. I have spark and fuel pressure, I know this because I can keep spraying with eether and it will run until I stop spraying. I know I have fuel pressure because I have a fuel pressure regulator with a gauge attached to the fuel rail, I have 60 Lbs..
I have checked and I do not have any codes or check engine light. I have done the 30 minute reset to no avail.
The cam and crank sensors are new along with a new battery.
I was thinking it might be the Antitheft system BUT, the security light does not stay on or blink when the key is turned to the on position. I have checked all the grounds.
Any ideas or help would be greatly appreciated. Thanks
Staging Lane
Joined: Jan 2017
Posts: 67
Likes: 1
Does it start without spraying either then die, or not start at all? I think with VATS it starts then dies.
Do the spark plugs fire? This will help confirm if the crank sensor is working.
If you have 12v to one wire of the injector, then verify that all PCM gounds are connected, I think there are 4 of them. You can check Lt1swap.com wire diagram to be sure. Also ground the PCM case itself as I have seen issues with that before.
Do the spark plugs fire? This will help confirm if the crank sensor is working.
If you have 12v to one wire of the injector, then verify that all PCM gounds are connected, I think there are 4 of them. You can check Lt1swap.com wire diagram to be sure. Also ground the PCM case itself as I have seen issues with that before.
Thread Starter
Teching In
Joined: Mar 2017
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It does start without either, then dies. I also thought VATS but the security light goes out, it does not stay on.
Do the spark plugs fire? are you asking as if I'm trying to start or crank it? it runs if I spray either so I would assume I have spark and the crank sensor would be working if I have spark.
I will check all grounds again, I have printed the wiring from LT1swap.com to check these last week.
Do the spark plugs fire? are you asking as if I'm trying to start or crank it? it runs if I spray either so I would assume I have spark and the crank sensor would be working if I have spark.
I will check all grounds again, I have printed the wiring from LT1swap.com to check these last week.
Staging Lane
Joined: Jan 2017
Posts: 67
Likes: 1
Sounds like a VATS issue to me. It is possible the BCM and PCM are not communicating and therefore you are not getting the VATS "Security" light?
Does not sound like a wiring issue since it will start on its own and you have verified good fuel pressure.
Does not sound like a wiring issue since it will start on its own and you have verified good fuel pressure.
Thread Starter
Teching In
Joined: Mar 2017
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So if it is a VATS issue or the BCM and PCM not communicating what are the best options? I have read many different sites about vats, I have seen different ways to wire a fix with a resistor and a relay. Some of the ways I have seen involve wiring an alarm or remote start, this involves a resistor and a couple relays. would this option fix the communication issues?
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Thread Starter
Teching In
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Correct! if the engine starts and runs then dies it is not the VATS.
I have figured out the problem and actually feel pretty stupid, the intake plenum from the cold air box to the throttle body was not connected so the MAF sensor was not seeing a pulse or and air flow, this is why the engine would start then die, no pulse from the MAF.
Thanks to all who commented and tried to help.
I have figured out the problem and actually feel pretty stupid, the intake plenum from the cold air box to the throttle body was not connected so the MAF sensor was not seeing a pulse or and air flow, this is why the engine would start then die, no pulse from the MAF.
Thanks to all who commented and tried to help.
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Verdad Gallardo Thread Starter
Teching In
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if the engine starts and runs then dies it is not the VATS.
I have figured out the problem and actually feel pretty stupid, the intake plenum from the cold air box to the throttle body was not connected so the MAF sensor was not seeing a pulse or and air flow, this is why the engine would start then die, no pulse from the MAF. if you dont have air movement by the MAF sensor you will have this problem.
Takodabash is online now Report Post
I have figured out the problem and actually feel pretty stupid, the intake plenum from the cold air box to the throttle body was not connected so the MAF sensor was not seeing a pulse or and air flow, this is why the engine would start then die, no pulse from the MAF. if you dont have air movement by the MAF sensor you will have this problem.
Takodabash is online now Report Post