Off throttle-on throttle jerking

[mikiedreb]

For quite a while now, I've been experiencing a rubberband like effect whenever I let off the throttle and then reapply it. A jerking motion. It was suggested that both motor mounts and subframe bushings should be checked. In the last 2 months I've replaced the motor mounts with ShoNut reinforced ones, a new tranny mount, and the subframe bushings with Gen III rear units. All I've accomplished thus far is to introduce more vibration into the interior of the car......the jerking still continues.

Would the front suspension be the next logical place to look....possibly bushings taking a dump?
I've been under there a number of times and nothing is visibly failing. Could failing clutch plate springs cause this much motion?

Thanks

Mike
92MTX

 

[Mike92Silver]

same thing for me too, checked mounts, and were fine, i cant explain it and im running rich cause i throw a code, but cant narrow the damn problem down!

 

[AutoSHO]

Sounds like your engine roll dampers are bad. They look like the struts used on the hood, but are smaller. I believe there are 3. One is located on the passenger side strut tower and runs down to the front of the engine. One is mounted on the front motor mount. The last one is on the driver's side, I do not remember the exact location. Try Ford Parts Network or SHO Nut Performance, they may have them or be able to locate some.

 

[mikiedreb]

Chris,
I don't doubt my roll dampers are worn, however, these new ShoNut reinforced mounts are damn stiff. I would have thought that with their installation, there would have been some reduction in the jerking motion......however there hasn't been.....as pronounced as ever.
Any other thoughts from the experts?
Thanks
Mike
92MTX

 

[projectSHO89]

Throttle position sensor? Throttle plate or cable sticking? IAB valve not responding quickly enough? (it has dashpot responsibilities)


Steve

 

[mikiedreb]

Steve,
Throttle position sensor recently replaced, throttle cable appears free and operates smoothly. IAB valve was also removed and cleaned....like new condition. Recent timing belt, cps, O2 sensors, cid, clutch cable, starter, battery and radiator. Plugs, wires and clutch 20k ago. Codes clear and cylinder balance test A-OK. (Talk about a $$$ pit!!!!) None of the above has effected this problem...not that they all were intended to. I'm still thinking front suspension........anybody got a **** of of a deal on aftermarket bushings, struts and coils? The money-tree out back is looking grim.

Thanks again

Mike
92MTX

 

[HopefulSHO]

projectSHO89:
(it has dashpot responsibilities)


Steve

What's that?

 

[jthomas68]

mikiedreb:
Chris,
I don't doubt my roll dampers are worn, however, these new ShoNut reinforced mounts are damn stiff. I would have thought that with their installation, there would have been some reduction in the jerking motion......however there hasn't been.....as pronounced as ever.
Any other thoughts from the experts?
Thanks
Mike
92MTX

The reinforced motor mounts don`t do much more for dampening over the stock ones.The only difference is the V channel welded to the pin.For the most part,that is to hold the mount together in case of tearing,it isn`t for a huge amount of increased dampening.

 

[projectSHO89]

quote:
--------------------------------------------------------------------------------
Originally posted by projectSHO89:
(it has dashpot responsibilities)


Steve
--------------------------------------------------------------------------------

What's that?

www.ask.com "What is a dashpot?"

 

[mikiedreb]

The reinforced motor mounts don`t do much more for dampening over the stock ones.The only difference is the V channel welded to the pin.For the most part,that is to hold the mount together in case of tearing,it isn`t for a huge amount of increased dampening

There's been a noticable increase in engine resonance in the car since I installed the mounts this weekend.......something has definately stiffened up !! Maybe I should try the old chain-from-motor-to-subframe trick as a test.

Mike
92MTX

 

[NJSHO]

Bringing an old thread up from the dead. I have the same problems that the original poster has. I have reinforced motor mounts, all new suspension bushings, and derlin subframe bushings and I still get this single buck when i get on the throttle down low, or go on of on again using anything but the lightest touch. These are the only 2 situations that I have this jerking/bucking. Could slop in the axles cause this? I did the shotimes motor mount test and the engine doesnt look like it was moving significantly. Any other ideas?

 

[slickn56]

the second poster in this thread (mike92silver) owned my silver sho before I bought it off of him.... When I picked it up it had that jerky motion in the drivetrain.... As soon as I got it home I gave it a good look over to make sure all the bolts were tight.... then I noticed the right side axle had a ripped boot and as soon as I replaced that axle the car drove much smoother through the gears. Also another thing it could be is that some clutches are much more forgiving on initial grab, that could cause it to **** if the clutch is brought up too quickly.

 

[AREA 91]

My guess is play in the axles.

 

[platoribs]

Read This!

I experienced this on my low mile bone stock 95. What I ultimately discovered was a collapsed vacuum line from the Idle bypass down to the Tee near the back/bottom of the radiator. Once I replaced it with a new vacuum specific tube (not the cheap silicone tubes, they collapse almost immediatly when they get hot) the problem went away.

Hope this helps!

 

[greenbeanmtx]

Greenbean had this problem and it turned out to be the TPS sensor had a dead spot in it. I replaced with a new one from autozone and the problem was still there but had changed. Then i got smart and bought a factory ford part and the problem went away. I thought it was something material like motor mounts or something of the like causing the problem but Scott Patterson told me to try the TPS and walllaaa the problem was solved. I forget how much it cost ( i want to say around 25 bucks or so) so its worth a shot. It probably wouldnt hurt to replace it anyways. Mine on my 89 was fine when i got it back from my sister but i replaced it anyways as part of the 60k service when i did it.