CEL after oil change and gas

[Stang 19]

Yes…wondering if the flap inside of the neck is not sealing? Eva system needs to be sealed they are tight and that little swinging flat that you push out-of-the-way with the nozzle could be a culprit as well.

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[melwff]

Yes…wondering if the flap inside of the neck is not sealing? Eva system needs to be sealed they are tight and that little swinging flat that you push out-of-the-way with the nozzle could be a culprit as well.

P0171 is not an evap code
https://www.obd-codes.com/p0171

 

[MAGS1]

I realize the battery discussion is off-topic from the OP's original question, but this IS A SAFETY ISSUE needing to be addressed.

Unfortunately Ford no longer gives instructions in the owner's manual on how to connect/disconnect batteries. (At least my 2019 manual avoids the topic.) I'm guessing it is because they fear liability of damage to their computerized systems resulting in a "he said, she said" situation should an owner do an oops.

The principles between charging and jumping are the same, for safety reasons, and for protecting vulnerable electronics in cars.

Anyway, Interstate Batteries has a couple good articles. I even learned something from the first linked article (step 5).
https://www.interstatebatteries.com/blog/official-way-to-jumpstart-a-battery

The second article is well worth reading also.

https://www.interstatebatteries.com/blog/how-to-disconnect-car-battery-terminals-safely

Ford Performance does put it in their instructions for parts installation. I pulled the strut tower brace as an example. Negative gets disconnected first

https://performanceparts.ford.com/download/instructionsheets/FORDINSTSHTM-20201-M-GT350.PDF

 

[Chola]

Exactly. Point proven. That’s what I’m saying. If you pull the positive and touch it to the body, that will do nothing. If you pull the negative and touch that to the body you are just regrounding the battery and powering the car again. Why chance that? Pull positive and if it touches anything it’s not going to matter?

BTW we are digressing from the first post.

I have been thinking of this (have an electronics engineering degree BTW), In theory it should not matter which you remove first. But in practice - it is different. The computer/audio systems etc will have some capacitors there that will hold the charge and cause a spark due to rapid discharge if the +ve cable (that is removed) touches the body.

I am sure someone can verify this by the following experiment.
Remove both +ve and -ve terminal from the battery (order not important). Then short the cables from the car together - one might say nothing should happen because neither is connected to a battery - but there will be a spark due to the rapid discharge of electricity stored in various circuits in the car that hold charge.

 

[ZXMustang]

BTW we are digressing from the first post.

I have been thinking of this (have an electronic engineering degree BTW), In theory it should not matter which you remove first. But in practice - it is different. The computer/audio systems etc will have some capacitors there that will hold the charge and cause a spark due to rapid discharge if the +ve cable (that is removed) touches the body.

I am sure someone can verify this by the following experiment.
Remove both +ve and -ve terminal from the battery (order not important). Then short the cables from the car together - one might say nothing should happen because neither is connected to a battery - but there will be a spark due to the rapid discharge of electricity stored in various circuits in the car that hold charge.

Look. I get it. But we are talking about after the positive lead is already disconnected. Sure if you touch ground with your wrench while you are disconnecting the positive cable then it would short. But if you’ve successfully removed that cable and put it to the side, then if it were to touch ground it will do nothing. Now the inverse of this is if you remove the negative side and accidentally touch that to the body/any ground while the positive is still attached to the battery then you’ve completed the circuit again and put power through the car. With more resistance I bet unless you are on a good clean ground.
Either way has a plus and minus. Just don’t be an idiot when disconnecting the battery. And this is in reference to just pulling one cable to discharge the cars module to reset any adaptives within the pcm/tcm/bcm and so on.

 

[Cory S]

if you remove the negative side and accidentally touch that to the body/any ground while the positive is still attached to the battery then you’ve completed the circuit

LOL. WHAT? That’s not even literally possible without the ground cable connected to the source.

 

[ZXMustang]

LOL. WHAT? That’s not even literally possible without the ground cable connected to the source.

Touch your negative to another chassis ground while the positive is still connected and see if you don’t get power. How are you even then able to jump a car without putting the negative on the battery but onto a chassis ground?? lol.

 

[Cory S]

Touch your negative to another chassis ground while the positive is still connected and see if you don’t get power. How are you even then able to jump a car without putting the negative on the battery but onto a chassis ground?? lol.

You’re not serious are you? If you PULL the negative cable off, the power source (battery) NO LONGER IS CONNECTED TO THE CHASSIS.

 

[Ruiner46]

Touch your negative to another chassis ground while the positive is still connected and see if you don’t get power. How are you even then able to jump a car without putting the negative on the battery but onto a chassis ground?? lol.

If there is no cable touching the battery, no power will flow period. The circuit has to be completed going back to the battery. If the battery only has one terminal connected, it will not provide power no matter which one is disconnected.

I think the rules are really about creating sparks. If you disconnect negative first, you do not risk creating a spark. If the wrench touches metal, since you are disconnecting negative/ground first, and all metal is grounded in the chassis, there is no risk of spark. If you disconnect positive first, and your wrench touches metal, you will get a light show.

 

[ZXMustang]

You’re not serious are you? If you PULL the negative cable off, the power source (battery) NO LONGER IS CONNECTED TO THE CHASSIS.

Unless you “accidentally” touch it to another chassis ground which can easily happen when most people try to tuck the cable to the side. Man have you been reading the replies?

 

[ZXMustang]

If there is no cable touching the battery, no power will flow period. The circuit has to be completed going back to the battery. If the battery only has one terminal connected, it will not provide power no matter which one is disconnected.

I think the rules are really about creating sparks. If you disconnect negative first, you do not risk creating a spark. If the wrench touches metal, since you are disconnecting negative/ground first, and all metal is grounded in the chassis, there is no risk of spark. If you disconnect positive first, and your wrench touches metal, you will get a light show.

Ive made that clear I thought.

 

[melwff]

LOL. WHAT? That’s not even literally possible without the ground cable connected to the source.

Exactly, nothing connected to negative terminal of BATTERY, no complete circuit

 

[Ruiner46]

Ive made that clear I thought.

You apparently don't know how a battery works. All a battery does is maintain a voltage between two terminals. If the negative battery cable is disconnected, then metal in the chassis is no longer at "ground". Metal doesn't magically mean ground. It only becomes ground when the battery negative is connected. If the battery negative is disconnected, it doesn't matter what you do with the negative cable. Touch it to anything you want, you won't get power until it's connected back to the battery.

 

[Hoofer]

Anyway, Interstate Batteries has a couple good articles. I even learned something from the first linked article (step 5).
https://www.interstatebatteries.com/blog/official-way-to-jumpstart-a-battery

The second article is well worth reading also.

https://www.interstatebatteries.com/blog/how-to-disconnect-car-battery-terminals-safely

Hey Nathan, thanks for posting this.

 

[ZXMustang]

You apparently don't know how a battery works. All a battery does is maintain a voltage between two terminals. If the negative battery cable is disconnected, then metal in the chassis is no longer at "ground". Metal doesn't magically mean ground. It only becomes ground when the battery negative is connected. If the battery negative is disconnected, it doesn't matter what you do with the negative cable. Touch it to anything you want, you won't get power until it's connected back to the battery.

So you're trying to tell me that a circuit that has hot side power connected to it cannot be grounded by any other means than the negative terminal of the power source thats connected to it?? Yeah thats not how any of this works. If power is still connected from the pos side of the battery, you can ground the circuit without using the negative side of the battery and you will get power. I've seen it, done it and been taught this. You better be careful if you are handling a hot side, and someone or something accidentally touch ground to the circuit you are connected to....

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