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Discussion Starter · #1 ·
What a job I installed Pypes long tube headers on my 2005 Roush Mustang.
1. One exhaust manifold bot broke. Welded a nut on it and got it out.
2. Oil dipstick tube would not come out. It broke off in the block. I tapped it out and threaded a bolt in it. I got it out.
3. I wrapped the headers before installing them.
Also installed new Pypes x pipe. I made the 10” down pipes.
I got everything back together and started the car and it would only idle. No throttle response.
So now I am trying to find out why. Everything is plugged in and connected.
 

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What a job I installed Pypes long tube headers on my 2005 Roush Mustang.
1. One exhaust manifold bot broke. Welded a nut on it and got it out.
2. Oil dipstick tube would not come out. It broke off in the block. I tapped it out and threaded a bolt in it. I got it out.
3. I wrapped the headers before installing them.
Also installed new Pypes x pipe. I made the 10” down pipes.
I got everything back together and started the car and it would only idle. No throttle response.
So now I am trying to find out why. Everything is plugged in and connected.
No throttle response meaning when you press the gas nothing happens at all? Like the rpm’s don’t move any? Could you have broken a wire somewhere somehow?
 

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Discussion Starter · #5 ·
No throttle response meaning when you press the gas nothing happens at all? Like the rpm’s don’t move any? Could you have broken a wire somewhere somehow?
No broken wires anywhere. When you press on gas pedal there’s is no response. Idles fine
 

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hmmm . . . random wild guess: O2 sensor(s) not plugged in or wiring fault?
 

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If it is missing when giving it throttle and not "responsive", you may have plugged your O2 sensors in backwards. If this is the case, you can take a datalog to confirm. Your short term fuel trims with max/min and flip by bank if they're backwards.
 

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If it is missing when giving it throttle and not "responsive", you may have plugged your O2 sensors in backwards. If this is the case, you can take a datalog to confirm. Your short term fuel trims with max/min and flip by bank if they're backwards.
I think it’s not working at all. Like he gives it gas and nothing happens.
 

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Get the old meter out and see if you have voltage to your TB,and work from there.
What he said. With the key on and engine off, probe the signal wire from the TPS with a digital multimeter and see if the voltage ramps up smoothly as you manually open the throttle blades.
Also double check all the electrical connections that you previously disconnected to perform the header swap. It's easy to plug the front O2 sensor harnesses in reverse but somehow I doubt that's the problem.
Did you disconnect the battery before you started? I just hope you haven't done something that could short out the ECU like disconnecting the positive cable first or reconnecting it last.
 

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What he said. With the key on and engine off, probe the signal wire from the TPS with a digital multimeter and see if the voltage ramps up smoothly as you manually open the throttle blades.
Also double check all the electrical connections that you previously disconnected to perform the header swap. It's easy to plug the front O2 sensor harnesses in reverse but somehow I doubt that's the problem.
Did you disconnect the battery before you started? I just hope you haven't done something that could short out the ECU like disconnecting the positive cable first or reconnecting it last.
I think the reason you disconnect the positive last is so you don’t accidentally touch something that’d make it arc before you got the neg off. He’d had notice sparks if he did.
 

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yeah this is the first time I heard of a correct or incorrect sequence for disconnecting or reconnecting a battery . . . I always thought that when a circuit is broken, it is broken and no current can flow; and it does not matter where or in what order it is broken (because the first break creates open circuit regardless)

when using jumper cables we were taught to make the last connection to the frame of the dead car on the negative cable; but the reason for that was to keep the spark away from the battery . . . when making the last connection, or removing the first connection, there can be a spark; from either positive or negative, it makes no difference as far as I know

What is the correct sequence for disconnecting and reconnecting?

And just to help me understand what is behind this; does this sequence have something to so with the way the ECU boots up when it receives power?

thanks in advance; and sorry for the tangent OP but I guess it's OK because you found your answer already
 

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Discussion Starter · #13 ·
Thanks for all the info. The issue was the throttle body controller. The butterflies were closed and when I turned the key on it would try to close it tighter. I took the controller off open the butterflies manually and re-installed the controller and all is fine. It is weird that it would happen after I installed the headers.
 

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yeah this is the first time I heard of a correct or incorrect sequence for disconnecting or reconnecting a battery . . . I always thought that when a circuit is broken, it is broken and no current can flow; and it does not matter where or in what order it is broken (because the first break creates open circuit regardless)
Any ASE Auto-tech training program teaches you to remove the ground connection 1st. It has nothing to do with the order that the circuit is broken. It has everything to do with avoiding accidental short-circuiting the system, and destroying electrical components. It’s very easy, and very common to accidentally let the wrench/ratchet handle bang against a grounded part while disconnecting the positive cable. Disconnecting the ground cable first prevents this from causing costly mistakes.

When reconnecting, the order is reversed.

And just to help me understand what is behind this; does this sequence have something to so with the way the ECU boots up when it receives power?
Nope. Has nothing to do with that.
 

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aha, thanks . . . and I guess there are some things besides chassis (coils, injectors, ...) within a wrench-length of the positive terminal so it makes sense
 

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Back in the day when alternators had a hot cable secured by a single nut at the back, this was particularly troublesome if you didn’t have a clue, and left the ground cable connected.
 

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Thanks for all the info. The issue was the throttle body controller. The butterflies were closed and when I turned the key on it would try to close it tighter. I took the controller off open the butterflies manually and re-installed the controller and all is fine. It is weird that it would happen after I installed the headers.
Yeah, that's indeed a headscratcher but glad you found the problem.

What is the correct sequence for disconnecting and reconnecting?
I was always taught to disconnect the negative battery cable first and reconnect it last. An accidental arcing isn't a big deal on older vehicles but it could damage the ECU on modern cars.
 
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