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Topic: Jerking and bucking issues (Read 1864 times) previous topic - next topic

Jerking and bucking issues

Need some input about a problem I'm having with my 86 XR7 turbo.  It's developed a jerking -  bucking -  stalling issue and we can't figure out what's wrong.  Thought it was a bad throttle position sensor but, replacing it did't solve the problem.  I can be going down the road at 40 or 45 mph and the car will just suddenly start jerking and bucking but will straighen out if I let off the accelerator just a tad or if I just BARELY depress the clutch (not nearly enough to disengage the clutch,  just enough to press the pedal down until it starts to apply pressure.)    Anybody got any ideas?
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Jerking and bucking issues

Reply #1 –
Will it buck and jerk driving off from a Stop sign?
[SIGPIC][/SIGPIC]

Jerking and bucking issues

Reply #3 –
Sometimes it will buck reeally hard when pulling out from a dead stop and then other times it starts bucking going down the road at a steady speed.
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Jerking and bucking issues

Reply #4 –
Spark plugs,  wires,  cap and button have about 15,000 on them.
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Jerking and bucking issues

Reply #5 –
Ok check codes and check the wires and plugs. Also check for coolant loss and nothing on the ground. Also very important to check fuel pressure and the regulator for a blown diaphragm.
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Jerking and bucking issues

Reply #6 –
Quote from: TOM Renzo;414182
Ok check codes and check the wires and plugs. Also check for coolant loss and nothing on the ground. Also very important to check fuel pressure and the regulator for a blown diaphragm.


We tried to check the codes by buying a tester from Auto Zone but it doesn't show anything.  Thing is,  for the most part she purrs along lime the Cat that is and does this jerking / buckinv thing intermittently.  That's why it's driving me batty - there doesn't seem to be any consistency to the problem and it just started doing it all of a sudden a few days ago.
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Jerking and bucking issues

Reply #8 –
Quote from: mercury-man;414184
sent you a pm CougarGal.
Replied with a question.
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Jerking and bucking issues

Reply #10 –
Plugs look good with no wear as do the wires.  Wasn't expecting them to look bad considering how well the car idles and runs mostb of the time.
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Jerking and bucking issues

Reply #11 –
Spark energy and consistency should be checked. PIP and TFI. I always assume people replace them at tune up time and i forget things like that. Having a scope i sometimes forget things as the scope is the first thing i hook up with issues like this. Spark blow out and spark scatter is common on the 2.3T. Also coils are another issue with them!!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Jerking and bucking issues

Reply #12 –
Quote from: TOM Renzo;414190
Spark energy and consistency should be checked. PIP and TFI. I always assume people replace them at tune up time and i forget things like that. Having a scope i sometimes forget things as the scope is the first thing i hook up with issues like this. Spark blow out and spark scatter is common on the 2.3T. Also coils are another issue with them!!!
TFI was just replaced as was the TPS - no improvement.  What is a PIP?
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Jerking and bucking issues

Reply #13 –
Also -  more info -  when it starts to buck and jerk,  I can press the clutch and it will immediaty smooth out and idle like a dream  :-(
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

Jerking and bucking issues

Reply #14 –
When converting my cruise control over to the 2003 mustang set up I found that the clutch switch is hot in start, and when not in start is used as a ground for the cruise control cancel circuit, when you push in the clutch it breaks the ground and  cancels the cruise. I don't think it is likely, but  maybe the cruise control amplifier or servo has some issues. Maybe there are some bare wires near the clutch pedal or shaft linkage and moving the pedal moves the wires. Just some ideas.