Fuel Slight jerking ?? HELP

CrazyChick08

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2005 Mustang GT. 5 speed manual.
The problem I'm having is theres a slight jerking(that bucks a little constantly until I let off or go faster) only at steady throttle. No matter what speed I'm doing, there's a noticable jerking and it's worse when I'm at low rpms in low gears.
I changed out the spark plugs, the fuel filter and I've cleaned the MAF and throttle body. It does not throw any codes! The rpm sometimes stays at 1000rpm at idle and doesn't go down until driving it a little. It's driving me crazy. If anyone knows anything, let me know!
No mods, all stock besides exhaust and catalytic converters were removed 4 months ago
 
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7991LXnSHO

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Old school answer, especially for a manual transmission or if it happens with the torque converter is locked up. Check the drive line components for play. U joints are the first suspect, but the yokes or rear gears could also have play in them. a transmission or motor mount is also possible, but way down the list percentage wise.
 
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CrazyChick08

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Old school answer, especially for s manual transmission or if it happens with the torque converter is locked up. Check the drive line components for play. U joints are the first suspect, but the yokes or rear gears could also have play in them. a transmission or motor mount is also possible, but way down the list percentage wise.
Ok thanks. I'll do that first
 

Bullitt95

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One thing you could try is resetting the throttle position as per the owner's manual. Turn the ignition to the ON position but don't start the engine. SLOWLY depress the gas pedal to the floor, hold for a second or two, and then slowly release. Repeat twice and then you should be good to go.
 

CrazyChick08

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One thing you could try is resetting the throttle position as per the owner's manual. Turn the ignition to the ON position but don't start the engine. SLOWLY depress the gas pedal to the floor, hold for a second or two, and then slowly release. Repeat twice and then you should be good to go.
Yeah, I've done it but it didn't change anything. I also notice a slight gurgling sound from the exhaust when it's idling too
 

7991LXnSHO

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Yeah, I've done it but it didn't change anything. I also notice a slight gurgling sound from the exhaust when it's idling too
That sound must be from the squirrels using mouthwash when they are not providing extra power. ;-)

The next steps I can think of involve scanning for codes and checking for ignition problems.
 
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7991LXnSHO

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I have no idea of your level of mechanical and diagnostic aptitude so I am going to ask for clarification.
Did you hook up a scan tool, not just seeing the check engine light is off? OBD 1 does not always set off the light with codes. I am not sure about this OBD2, but GM’s have been known to count intermittent misfires without setting off the dash light. VW on the other hand likes to make the dash pretty with all the check stuff lights.
 

CrazyChick08

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I have no idea of your level of mechanical and diagnostic aptitude so I am going to ask for clarification.
Did you hook up a scan tool, not just seeing the check engine light is off? OBD 1 does not always set off the light with codes. I am not sure about this OBD2, but GM’s have been known to count intermittent misfires without setting off the dash light. VW on the other hand likes to make the dash pretty with all the check stuff lights.
I have put a scan tool in and did monitor the performance of the car. The only thing that struck out is when I went to see the drive cycle and it said under components: incomplete and misfire: incomplete
 

7991LXnSHO

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That’s what I was hoping for. The good news is that a tune up (wires, plugs, check the coil or coils and other ignition components) is likely to fix the issue.
 

CrazyChick08

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That’s what I was hoping for. The good news is that a tune up (wires, plugs, check the coil or coils and other ignition components) is likely to fix the issue.
I thought about that but wasn't sure. But another question is the PCV valve. Would that likely be the issue? I read where they can get stuck open. Plus there's oil inside the hose itself
 

7991LXnSHO

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I have never heard of a malfunctioning PCV system causing misfire symptoms. Some oil in the PVC hose from the crank case vapors is not unusual. If in doubt, replace the valve to help with oil consumption. They are usually a small price item.
 

CrazyChick08

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I have never heard of a malfunctioning PCV system causing misfire symptoms. Some oil in the PVC hose from the crank case vapors is not unusual. If in doubt, replace the valve to help with oil consumption. They are usually a small price item.
Ok thanks. The things I've read online said they could cause surging, which I have and misfire at idle which I'm sure also
 

racerraj

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Does the engine run smooth, do you hear any misfire? Maybe try unplugging one coil pack at a time and make sure it the sound changes each time. If one cylinder doesn't change, that one is misfiring. Could be Plug (Which isn't likely since you changed them), coil pack, or fuel injector. Move the coil pack to another cylinder to see of the problem follows the coil pack. But I am guessing it is running smooth. As someone mentioned, ujoints can cause that feeling too. Maybe get up to speed, throw it in neutral, shut the motor off. If the jerking is still there then it would likely be driveline related - driveshaft, ujoints, bearings, and such.
 
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CrazyChick08

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Does the engine run smooth, do you hear any misfire? Maybe try unplugging one coil pack at a time and make sure it the sound changes each time. If one cylinder doesn't change, that one is misfiring. Could be Plug (Which isn't likely since you changed them), coil pack, or fuel injector. Move the coil pack to another cylinder to see of the problem follows the coil pack. But I am guessing it is running smooth. As someone mentioned, ujoints can cause that feeling too. Maybe get up to speed, throw it in neutral, shut the motor off. If the jerking is still there then it would likely be driveline related - driveshaft, ujoints, bearings, and such.
It doesn't idle smooth. The rpms stay at 1000 up until I start driving it a little. Theres a slight misfire at idle and when I'm in low gears(1st or 2nd) driving slow, theres definitely a noticable surging and hesitation until I go faster or get into a higher gear
 

racerraj

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High idle may be from a vacuum leak somewhere. Which can cause it to run lean and cause misfires. Can you hear a hiss under the hood around the engine area? Check all vacuum hoses.
 

CrazyChick08

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High idle may be from a vacuum leak somewhere. Which can cause it to run lean and cause misfires. Can you hear a hiss under the hood around the engine area? Check all vacuum hoses.
I already did a vacuum leak test and couldn't find any. There is a hissing now that comes from the engine