Car jerks after while accelerating after 40mph - Mazda Forum
Reply
 
LinkBack Thread Tools
post #1 of 26 (permalink) Old 09-19-2007, 01:14 AM Thread Starter
Junior Member
 
Join Date: Jul 2003
Posts: 164
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Hey,

Am lookign for some input.
At about 40 mph, my car starts jerking when I accelerate.
It does it off and on.
Any ideas?

Clarification
Yeah, what it does is if I go past 40 then let it deaccelerate down to like 36 and then try to accelerate again, I get a jerking movement everytime I try to accelearte. It doesn't just jerk once then accelerate smoothly, it is a continuous jerk like the car loses power than accelerates then loses power than accelerates. and it continues cfrom like 40 -60 mph. I hope that is a little clearer.
emperus is offline  
Sponsored Links
Advertisement
 
post #2 of 26 (permalink) Old 09-19-2007, 01:24 AM
Super Moderator
 
Join Date: Aug 2007
Location: Miami, Fl
Posts: 2,065
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
If its when upshifting after just downshifting my car does that too sometimes but not really hard jerking. After the tranny fluid flush it got a little better.
-Steven



<span style="font-family:Verdana">2001 Mazda Millenia L R.I.P
SteveSter is offline  
post #3 of 26 (permalink) Old 09-19-2007, 01:52 AM
Platinum Member
 
millyowner's Avatar
 
Join Date: Nov 2003
Location: Oklahoma City
Posts: 5,755
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Under light throttle, mine kind of jerks slightly sometimes like it's alternating between coasting and engine braking. I figure it might be a badly adjusted TPS or maybe the sensor itself is worn or tracked.
millyowner is offline  
post #4 of 26 (permalink) Old 09-19-2007, 03:34 PM Thread Starter
Junior Member
 
Join Date: Jul 2003
Posts: 164
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yeah, what it does is if I go past 40 then let it deaccelerate down to like 36 and then try to accelerate again, I get a jerking movement everytime I try to accelearte. It doesn't just jerk once then accelerate smoothly, it is a continuous jerk like the car loses power than accelerates then loses power than accelerates. and it continues cfrom like 40 -60 mph. I hope that is a little clearer.
emperus is offline  
post #5 of 26 (permalink) Old 09-19-2007, 04:19 PM
Platinum Member
 
Saint_'s Avatar
 
Join Date: Nov 2006
Location: California,US
Posts: 4,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
How much throttle do you apply? Did you try full throttle? If not try it. Does TCS flash while jerking?

And what year trim mileage?

Quote:
Yeah, what it does is if I go past 40 then let it deaccelerate down to like 36 and then try to accelerate again, I get a jerking movement everytime I try to accelearte. It doesn't just jerk once then accelerate smoothly, it is a continuous jerk like the car loses power than accelerates then loses power than accelerates. and it continues cfrom like 40 -60 mph. I hope that is a little clearer.[/b]

2001 Mazda Millenia S 178k Brilliant Black
Saint_ is offline  
post #6 of 26 (permalink) Old 09-19-2007, 04:33 PM
Platinum Member
 
millyowner's Avatar
 
Join Date: Nov 2003
Location: Oklahoma City
Posts: 5,755
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
If it's the same as mine, the jerking goes away once you press the accelerator a little further. It only happens when the throttle is barely pressed (like slow acceleration above 45mph) or accending a very slight grade at a constant speed. The throttle sensitivity on the miller cycle is such that driving normally requires very small throttle inputs to keep from lurching forward. In comparison to the 2.5L, it's on the opposite end of the spectrum requiring large input for small changes in acceleration at some speeds. I was thinking that the TPS is sending erratic output to the ECM when it is in that almost closed position or the closed throttle position sensor is sending "open----close-open-------close-----open" causing the jerking. No way to tell for sure until you (and I) drive with an OBDII data logger and monitor the TPS and CTPS output while the jerking occurs.
millyowner is offline  
post #7 of 26 (permalink) Old 09-19-2007, 04:35 PM Thread Starter
Junior Member
 
Join Date: Jul 2003
Posts: 164
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
How much throttle do you apply? Did you try full throttle? If not try it. Does TCS flash while jerking?

And what year trim mileage?[/b]
Have not tried full throttle. Will try it. TCs does not flash..

It is a 99 L 98,000
emperus is offline  
post #8 of 26 (permalink) Old 09-19-2007, 05:45 PM
Junior Member
 
Terrentius's Avatar
 
Join Date: Sep 2006
Location: New Brunswick, Canada
Posts: 150
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I have same the same issue with my ride. I am wondering what it is as well. I have no CEL and the traction control does not come on either. I am leaning towards something to do with the fuel system....

-2001 Mazda Millenia S
-Pilot HID 4300K LOWS
-K&N Filter
-Mobil 1 Synthetic
-5% Tint Sunroof and Rear Windows
-FUZION HRi Shoes
Terrentius is offline  
post #9 of 26 (permalink) Old 09-20-2007, 12:34 PM
Platinum Member
 
millyowner's Avatar
 
Join Date: Nov 2003
Location: Oklahoma City
Posts: 5,755
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
I have same the same issue with my ride. I am wondering what it is as well. I have no CEL and the traction control does not come on either. I am leaning towards something to do with the fuel system....[/b]
That's why I'm thinking that it might be something with the TPS or CTS. When your foot comes off the accelerator at speed, the fuel injectors switch to a 0% duty cycle. If the ECM *thinks* the accelerator isn't depressed (when it really is if only slightly), it cuts fuel and causes a mild jerk. My dad had a mid-90s 4-cylinder Camry years ago that did the same thing and we never figured it out. The only things I can think of are a bad CTS or a TPS with erratic output voltage throughout its range or within a small portion of its range.

Erratic TPS output can also cause the automatic transmission to shift abruptly every now and then depending on throttle input. The ECM really depends on accurate TPS readings to smooth the shift shock between gears. My transmission shifts smoothly for the most part, but every now and again, a light throttle 1-2, or 2-3 shift will make the car buck a bit. All the more reason to blame the TPS I suppose.
millyowner is offline  
post #10 of 26 (permalink) Old 09-20-2007, 02:04 PM
Platinum Member
 
Saint_'s Avatar
 
Join Date: Nov 2006
Location: California,US
Posts: 4,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
This also means it consumes no fuel when cruising (fast enough). Thats why i let it slow down itself by just releasing the accelerator when exiting highway, if traffic allows.

Quote:
When your foot comes off the accelerator at speed, the fuel injectors switch to a 0% duty cycle.[/b]
I wonder if the TPS can be cleaned/serviced? Apperantly the idle signal in the picture below may dominate over throttle valve opening signal for small inputs..


2001 Mazda Millenia S 178k Brilliant Black
Saint_ is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Mazda Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome