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LS won't rev. Please help!!!

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Old 03-27-2014, 05:11 PM
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Default LS won't rev. Please help!!!

Starts and runs great until I hit the gas. If you hold the throttle with steady pressure it revs to about 1340 rpms then it shuts off the injectors until about 950 rpms. Sounds just like a rev limiter, but way lower rpms.

Motor is 2006 LS2. Intake, ECM& harness are 01-02
Confirmed the motor is a 24x-4x crank and a 1x cam.
Fuel pressure is good
All sensors look like they are working on the lab scope
ECM has all security deleted and is stand alone
Even installed the ECM into a friends 00 pick-up and it works fine.
Confirmed when it does this the spark is still good.
The crank and cam are matching up on the lab scope.
It will rev if you leave tps plugged in but disconnected from throttle body and manually set at zero. If it has any voltage it won't rev.
BTW I am NOT a mechanic so if anyone has any ideas please talk slow and in terms a third grader would understand.

I gave up and took it to a mechanic, now he is ready to give up.
Please help!
Old 03-28-2014, 10:06 PM
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Reach around behind the intake and check the MAP sensor, make sure it's plugged in electrically and plugged into the port on the manifold. Also make sure nothing is wrong with the MAF, as in no dirt or debris in the wires or stuck to the screen. Someone with a good scan tool should be able to look at live data and get a good idea what values the ECM is seeing and causing the trouble. Good luck, I hope you can figure it out. If you were around central Ohio I wouldn't mind helping out I like solving these types of issues.
Old 03-30-2014, 12:55 AM
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Fuel pump Is bad
Old 03-30-2014, 12:59 AM
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Originally Posted by Bronc j-8
Starts and runs great until I hit the gas. If you hold the throttle with steady pressure it revs to about 1340 rpms then it shuts off the injectors until about 950 rpms. Sounds just like a rev limiter, but way lower rpms.

Motor is 2006 LS2. Intake, ECM& harness are 01-02
Confirmed the motor is a 24x-4x crank and a 1x cam.
Fuel pressure is good
All sensors look like they are working on the lab scope
ECM has all security deleted and is stand alone
Even installed the ECM into a friends 00 pick-up and it works fine.
Confirmed when it does this the spark is still good.
The crank and cam are matching up on the lab scope.
It will rev if you leave tps plugged in but disconnected from throttle body and manually set at zero. If it has any voltage it won't rev.
BTW I am NOT a mechanic so if anyone has any ideas please talk slow and in terms a third grader would understand.

I gave up and took it to a mechanic, now he is ready to give up.
Please help!
Fuel pump is bad? Please explain!
Old 03-30-2014, 01:17 AM
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Originally Posted by 2000Hawk#317
Fuel pump is bad? Please explain!
**** missed that part, it's late


My car had a similar issue and it was the intake air temperature sensor being broken and the ECM reading -256 degrees and throwing tons of fuel and timing in the motor which eventually killed my pump
Old 03-30-2014, 12:35 PM
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Checked the map sensor and it is reading. Swapped out maf sensor and it still does it. Ready to buy a whole new harness but I'm not sure that's the problem.
Old 03-30-2014, 04:18 PM
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Originally Posted by Bronc j-8
Starts and runs great until I hit the gas. If you hold the throttle with steady pressure it revs to about 1340 rpms then it shuts off the injectors until about 950 rpms. Sounds just like a rev limiter, but way lower rpms.

Motor is 2006 LS2. Intake, ECM& harness are 01-02
Confirmed the motor is a 24x-4x crank and a 1x cam.
Fuel pressure is good
All sensors look like they are working on the lab scope
ECM has all security deleted and is stand alone
Even installed the ECM into a friends 00 pick-up and it works fine.
Confirmed when it does this the spark is still good.
The crank and cam are matching up on the lab scope.
It will rev if you leave tps plugged in but disconnected from throttle body and manually set at zero. If it has any voltage it won't rev.
BTW I am NOT a mechanic so if anyone has any ideas please talk slow and in terms a third grader would understand.

I gave up and took it to a mechanic, now he is ready to give up.
Please help!
Did the car run perfect for a long period of time.....and this just started? Or is this a new combo you put together and it has never run right?

.
Old 03-30-2014, 06:05 PM
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Originally Posted by LS6427
Did the car run perfect for a long period of time.....and this just started? Or is this a new combo you put together and it has never run right?

.
This is a new combo I just swapped into my jeep. Never ran right yet.



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