Frustrating lurch when accelerating from a stop
2/27/23, 03:16 PM
#1
Member
Thread Starter
Frustrating lurch when accelerating from a stop
Hi all,
I'm having a frustrating issue with my 2005 Mustang GT hat I've had since I first got it almost 3 years ago.
For starters, it's a 5 speed manual transmission and is 100% stock. It is also in incredible shape and condition.
Secondly, I've been driving only manual transmission cars my whole driving career (about 25 years now) and have never owned an automatic. The only automatic I had, I converted to a manual. I'm a manual transmission guy, so I'm well seasoned in driving them both on and off road.
But this is just driving me crazy! When I'm starting out from a stop in 1st gear, and I let out the clutch and give it just a small amount of gas, the car will often launch so hard that it throws my foot off the gas pedal, which then causes the vehicle to decelerate and engine brake, which then throws all the momentum forward and my foot back onto the gas pedal, which causes it to accelerate and surge, which throws my foot off the gas, etc. etc. etc. Causing the whole vehicle to lurch and surge. It has nothing to do with fuel, ignition, etc. etc. This is PURELY physics. Sometimes I can get a smooth start, but nothing I do will guarantee success.
About the only surefire way to not have this issue is to accelerate aggressively. Like, when I really want to have some fun, leave everyone behind me at the light, and just go. It launches beautifully.
This issue is only when I'm trying to NOT accelerate hard, like driving in my neighborhood or around in a parking lot. Low speed, gentle takeoffs are the worst.
It happened the very first time I test drove it and I thought it was just a matter of me needing to learn the feel of a different car I hadn't driven before. But almost three years later, I'm still struggling with it, to the point where it can get embarrassing and downright obnoxious. Other people who've driven it have had the same issue, too.
I'm just wondering if there's something that's actually going on. Basically, at the end of the day, it feels like the engine has a throttle body that's twice the size of what it should be. Like, just a small amount of throttle movement is just really opening the engine up. It literally feels like 2 - 3% of the throttle movement is equivalent 10 - 20% in other cars, and I have to really tense my ankle up to really control the throttle.
Can anyone think of what's causing this? Is this a known issue? Is it a weak throttle spring? What?
Any thoughts or ideas would be great.
I'm having a frustrating issue with my 2005 Mustang GT hat I've had since I first got it almost 3 years ago.
For starters, it's a 5 speed manual transmission and is 100% stock. It is also in incredible shape and condition.
Secondly, I've been driving only manual transmission cars my whole driving career (about 25 years now) and have never owned an automatic. The only automatic I had, I converted to a manual. I'm a manual transmission guy, so I'm well seasoned in driving them both on and off road.
But this is just driving me crazy! When I'm starting out from a stop in 1st gear, and I let out the clutch and give it just a small amount of gas, the car will often launch so hard that it throws my foot off the gas pedal, which then causes the vehicle to decelerate and engine brake, which then throws all the momentum forward and my foot back onto the gas pedal, which causes it to accelerate and surge, which throws my foot off the gas, etc. etc. etc. Causing the whole vehicle to lurch and surge. It has nothing to do with fuel, ignition, etc. etc. This is PURELY physics. Sometimes I can get a smooth start, but nothing I do will guarantee success.
About the only surefire way to not have this issue is to accelerate aggressively. Like, when I really want to have some fun, leave everyone behind me at the light, and just go. It launches beautifully.
This issue is only when I'm trying to NOT accelerate hard, like driving in my neighborhood or around in a parking lot. Low speed, gentle takeoffs are the worst.
It happened the very first time I test drove it and I thought it was just a matter of me needing to learn the feel of a different car I hadn't driven before. But almost three years later, I'm still struggling with it, to the point where it can get embarrassing and downright obnoxious. Other people who've driven it have had the same issue, too.
I'm just wondering if there's something that's actually going on. Basically, at the end of the day, it feels like the engine has a throttle body that's twice the size of what it should be. Like, just a small amount of throttle movement is just really opening the engine up. It literally feels like 2 - 3% of the throttle movement is equivalent 10 - 20% in other cars, and I have to really tense my ankle up to really control the throttle.
Can anyone think of what's causing this? Is this a known issue? Is it a weak throttle spring? What?
Any thoughts or ideas would be great.
Last edited by JustangGT; 2/27/23 at 03:23 PM.
2/27/23, 04:18 PM
#2
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Are you sure it does not have an aftermarket tune? The "bucking" that you describe sometimes relates to exaggerated throttle response.
But I have experienced "bucking" with my near-stock 2010 GT also, and I don't think it was caused by the tune. I think it is a result of the drive-by-wire system, and the small lag in time, between when you press the gas, and when the car responds. I think my brain/foot are trying to compensate for the lack of response by giving it more gas, which gives too much power when it does respond, so then you automatically let off, and the bucking cycle starts.
Or maybe it's caused by something else, I don't know ... but yeah "bucking" on slow starts, especially when the engine is not fully warmed up, is a thing with these cars.
It might be worth a try to clean the throttle body and try the idle reset procedure, just in case the ECU has learned bad habits.
But I have experienced "bucking" with my near-stock 2010 GT also, and I don't think it was caused by the tune. I think it is a result of the drive-by-wire system, and the small lag in time, between when you press the gas, and when the car responds. I think my brain/foot are trying to compensate for the lack of response by giving it more gas, which gives too much power when it does respond, so then you automatically let off, and the bucking cycle starts.
Or maybe it's caused by something else, I don't know ... but yeah "bucking" on slow starts, especially when the engine is not fully warmed up, is a thing with these cars.
It might be worth a try to clean the throttle body and try the idle reset procedure, just in case the ECU has learned bad habits.
The following users liked this post:
NC14GT (2/28/23)
2/27/23, 09:29 PM
#3
THE RED FLASH ------ Master-Moderator
From what you describe, it seems like you may have a 93-octane race tune which does provide more of an aggressive throttle response... I would start by finding out whether you have an aftermarket calibration tune or stock calibration uploaded into your vehicle's ECM via the OBDII port 
2/28/23, 07:32 AM
#4
Gotta Have it Green Fanatic Official TMS Travel Guide
Are you sure it does not have an aftermarket tune? The "bucking" that you describe sometimes relates to exaggerated throttle response.
But I have experienced "bucking" with my near-stock 2010 GT also, and I don't think it was caused by the tune. I think it is a result of the drive-by-wire system, and the small lag in time, between when you press the gas, and when the car responds. I think my brain/foot are trying to compensate for the lack of response by giving it more gas, which gives too much power when it does respond, so then you automatically let off, and the bucking cycle starts.
Or maybe it's caused by something else, I don't know ... but yeah "bucking" on slow starts, especially when the engine is not fully warmed up, is a thing with these cars.
It might be worth a try to clean the throttle body and try the idle reset procedure, just in case the ECU has learned bad habits.
But I have experienced "bucking" with my near-stock 2010 GT also, and I don't think it was caused by the tune. I think it is a result of the drive-by-wire system, and the small lag in time, between when you press the gas, and when the car responds. I think my brain/foot are trying to compensate for the lack of response by giving it more gas, which gives too much power when it does respond, so then you automatically let off, and the bucking cycle starts.
Or maybe it's caused by something else, I don't know ... but yeah "bucking" on slow starts, especially when the engine is not fully warmed up, is a thing with these cars.
It might be worth a try to clean the throttle body and try the idle reset procedure, just in case the ECU has learned bad habits.
2/28/23, 10:21 AM
#5
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Juststang,
I would also suspect the Throttle Pedal Sensor and or Throttle Body Control may have a Bad or Dirty Spot on the Contact Points. Some Electrical Contact Cleaner if You Can Find an Access Hole/Point Would Be a Cheap Try. Now if Contacts are Burnt Replacement is Only Option.
Be Advised the Contact Cleaner is Just for The Electronic Part of T/B. A Good T/B Clean Is Also a Great Idea!
I Have Lot's of Audio Equipment from the 80's and Have Dirty Switches which I had to clean in the Past. I recently changed to the WD-40 Brand And Wow it Worked Even Better Compared to the CRC I had Used in the Past.
https://www.walmart.com/ip/WD-40-Spe...4&gclsrc=3p.ds
Be Advised Your Throttle is a Very Important Item and Use at Your Own Risk. Just Saying This Stuff Worked Great on a 40+ Year Old Piece of Electronics that would Drop out During Use.
A Dirty Mass Air Flow Sensor Can Cause Havoc as Well. While I Knocked the CRC Contact Cleaner I Have Had Good Luck With these. I Don't Really Care For Walmart or Amazon But Like to Post Exact Pics of Items I Suggest. Local Parts Houses Carry Some of These Items. Anyhoo Just Another Thing To Try!
Everybody has Posted Some Great Idea's and Others may Post Additional Ones. That's The Great Thing Here as we all Have a Piece of the Pie to Add our Collective Experience to Your Issue!
https://www.walmart.com/ip/CRC-Mass-...b&gclsrc=3p.ds
Best of Luck on the Repair!
KC
I would also suspect the Throttle Pedal Sensor and or Throttle Body Control may have a Bad or Dirty Spot on the Contact Points. Some Electrical Contact Cleaner if You Can Find an Access Hole/Point Would Be a Cheap Try. Now if Contacts are Burnt Replacement is Only Option.
Be Advised the Contact Cleaner is Just for The Electronic Part of T/B. A Good T/B Clean Is Also a Great Idea!
I Have Lot's of Audio Equipment from the 80's and Have Dirty Switches which I had to clean in the Past. I recently changed to the WD-40 Brand And Wow it Worked Even Better Compared to the CRC I had Used in the Past.
https://www.walmart.com/ip/WD-40-Spe...4&gclsrc=3p.ds
Be Advised Your Throttle is a Very Important Item and Use at Your Own Risk. Just Saying This Stuff Worked Great on a 40+ Year Old Piece of Electronics that would Drop out During Use.
A Dirty Mass Air Flow Sensor Can Cause Havoc as Well. While I Knocked the CRC Contact Cleaner I Have Had Good Luck With these. I Don't Really Care For Walmart or Amazon But Like to Post Exact Pics of Items I Suggest. Local Parts Houses Carry Some of These Items. Anyhoo Just Another Thing To Try!
Everybody has Posted Some Great Idea's and Others may Post Additional Ones. That's The Great Thing Here as we all Have a Piece of the Pie to Add our Collective Experience to Your Issue!
https://www.walmart.com/ip/CRC-Mass-...b&gclsrc=3p.ds
Best of Luck on the Repair!
KC
Last edited by 05stangkc; 2/28/23 at 10:51 AM.
The following users liked this post:
JuneCraddock (3/13/23)
3/13/23, 07:39 AM
#6
Juststang,
I would also suspect the Throttle Pedal Sensor and or Throttle Body Control may have a Bad or Dirty Spot on the Contact Points. Some Electrical Contact Cleaner if You Can Find an Access Hole/Point Would Be a Cheap Try. Now if Contacts are Burnt Replacement is Only Option.
Be Advised the Contact Cleaner is Just for The Electronic Part of T/B. A Good T/B Clean Is Also a Great Idea!
I Have Lot's of Audio Equipment from the 80's and Have Dirty Switches which I had to clean in the Past. I recently changed to the WD-40 Brand And Wow it Worked Even Better Compared to the CRC I had Used in the Past.
https://www.walmart.com/ip/WD-40-Spe...4&gclsrc=3p.ds
Be Advised Your Throttle is a Very Important Item and Use at Your Own Risk. Just Saying This Stuff Worked Great on a 40+ Year Old Piece of Electronics that would Drop out During Use.
A Dirty Mass Air Flow Sensor Can Cause Havoc as Well. While I Knocked the CRC Contact Cleaner I Have Had Good Luck With these. I Don't Really Care For Walmart or Amazon But Like to Post Exact Pics of Items I Suggest. Local Parts Houses Carry Some of These Items. Anyhoo Just Another Thing To Try!
Everybody has Posted Some Great Idea's and Others may Post Additional Ones. That's The Great Thing Here as we all Have a Piece of the Pie to Add our Collective Experience to Your Issue!
https://www.walmart.com/ip/CRC-Mass-...b&gclsrc=3p.ds
Best of Luck on the Repair!
KC
I would also suspect the Throttle Pedal Sensor and or Throttle Body Control may have a Bad or Dirty Spot on the Contact Points. Some Electrical Contact Cleaner if You Can Find an Access Hole/Point Would Be a Cheap Try. Now if Contacts are Burnt Replacement is Only Option.
Be Advised the Contact Cleaner is Just for The Electronic Part of T/B. A Good T/B Clean Is Also a Great Idea!
I Have Lot's of Audio Equipment from the 80's and Have Dirty Switches which I had to clean in the Past. I recently changed to the WD-40 Brand And Wow it Worked Even Better Compared to the CRC I had Used in the Past.
https://www.walmart.com/ip/WD-40-Spe...4&gclsrc=3p.ds
Be Advised Your Throttle is a Very Important Item and Use at Your Own Risk. Just Saying This Stuff Worked Great on a 40+ Year Old Piece of Electronics that would Drop out During Use.
A Dirty Mass Air Flow Sensor Can Cause Havoc as Well. While I Knocked the CRC Contact Cleaner I Have Had Good Luck With these. I Don't Really Care For Walmart or Amazon But Like to Post Exact Pics of Items I Suggest. Local Parts Houses Carry Some of These Items. Anyhoo Just Another Thing To Try!
Everybody has Posted Some Great Idea's and Others may Post Additional Ones. That's The Great Thing Here as we all Have a Piece of the Pie to Add our Collective Experience to Your Issue!
https://www.walmart.com/ip/CRC-Mass-...b&gclsrc=3p.ds
Best of Luck on the Repair!
KC
3/13/23, 07:39 AM
#7
Thanks for the help, you made my day and if I want to ask more, I will message you My mentor gave me a lot of essay tasks, and my parents informed me that if I didn't finish my homework, they wouldn't let me leave the house. I located an essay writer via the SPAMMER website, where I saw papersowl reviews that helped me trust their essay writers. When I finish my homework, I'll attempt to make a trip over there.
My mentor gave me a lot of essay tasks, and my parents informed me that if I didn't finish my homework, they wouldn't let me leave the house. I located an essay writer via the SPAMMER website, where I saw papersowl reviews that helped me trust their essay writers. When I finish my homework, I'll attempt to make a trip over there.
Last edited by 05stangkc; 7/18/23 at 10:49 AM.
3/13/23, 09:10 PM
#8
THE RED FLASH ------ Master-Moderator
https://themustangsource.com/forums/f650/
7/18/23, 10:49 AM
#9
Administrator, Shop Manual PDF Poster, Parts Locator & Spam Bot Eliminator!!
Join Date: November 27, 2004
Location: Visalia Ca.
Posts: 10,551
Received 2,861 Likes
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Thanks for the help, you made my day and if I want to ask more, I will message you My mentor gave me a lot of essay tasks, and my parents informed me that if I didn't finish my homework, they wouldn't let me leave the house. I located an essay writer via the SPAMMER website, where I saw papersowl reviews that helped me trust their essay writers. When I finish my homework, I'll attempt to make a trip over there.
My mentor gave me a lot of essay tasks, and my parents informed me that if I didn't finish my homework, they wouldn't let me leave the house. I located an essay writer via the SPAMMER website, where I saw papersowl reviews that helped me trust their essay writers. When I finish my homework, I'll attempt to make a trip over there.KC
7/18/23, 02:21 PM
#10
THE RED FLASH ------ Master-Moderator
Sure got that right, as I wasn't really sure if it was spam or not spam!
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