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Variable Effort Steering (VES) has erratic boost

38408 Views 60 Replies 24 Participants Last post by  Fred Kiehl
The issue I'm having is kind of hard to explain. Say for instance I'm driving on the highway and when I slightly turn the wheel, either left or right to change lanes, my steering wheel jerks to that side. It's not bump steer, because this happens on the smoothest of roads, and only happens when I slightly turn the steering wheel left or right to change lanes. My inner and outer tie rods are Moog, and less than a year old. My Idler arm is ac delco and less than a month old. Could the steering box be causing this?
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It's quite common, but only thought it was for Fleetwoods. It's referred to as 'cloverleaf jerkover'. Best of anyone's accounting the var. assist can't compute small demands and has a heart attack for a split sec. Unplugging the electrical plug something something either on the worm gear or near the firewall puts everything in fulltime fullpower assist and you never have the problem.

Since it's never evident anywhere but interstate speeds I just expect it on all changes of direction and it's just say meh.
I recall attention given to that valve and my vague takeaway was messing with it did not change the condition. Believe me, if simply throwing a little money at it and swapping out a little valve could have eradicated the issue then I would have entertained it seriously. Unless of course said valve had been found to cost $300. cwm1

For the issue to be the same malady as what I'm describing it can only be 1. at hiway speeds and 2. only during steady-state gradual curves like turnoffs. The issue is certainly unnerving when it occurs, but it's only every few months for me. Anything different in the symptoms and it may be a bonafide steering, susp. or pump failure problem. I had a hogged out spindle bj hole once that repositioned itself on steep turns that took a while to trace down. And, of course a bad UCA bushing can cause a jerk problem. Those would usually come with a clunk noise though.

I honestly did not notice much difference in effort supposedly going to fulltime boost when I had one of those connectors unplugged (recall it was at the firewall). But then again if memory serves the FWB has a very 'unquick' box ratio to start with.

I will say one thing - official amateur studies in the FWB section showed thorough ps fluid flush decreased the incidence of this problem - a little.
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Unplug the four-pin potentiometer connector from the bottom of the steering column near the firewall (engine side). Problem gone forever in my car... just have full assist at all times. Much better than having scary steering through curves.

And you haven't experienced anything bad yet until it happens to you on ice or snow covered off ramp curve!!!

I give GM a 0 out of 10 for using a potentiometer on the steering column instead of an LVDT for this variable effort steering system.

Thanks Northern-. If that goof in Post #5 had had a little better command of the technical nomenclature surrounding this issue then I bet everybody woulda' believed him more. hahahahahahaha ;)

For HUF, as I posted I could tell absolutely no difference in either steering effort or response comparing unconnected to connected.
Thanks for the two fixes Joel, -- and for making this a stickie.
You Dam Right It's Worth TTT

My new FWB has ~53,XXX, but if ghost grab/cloverleaf jerkover raises its head I'll just do Sherlock's resistor bypass. Unplugging the potentiometer is a fast close second choice for fix. I never could tell ANY difference between normal and full boost, and VES seems pretty senseless overall.
Some added info, some you may have already figured:

Impalas do not have VES, so nothing applicable to your case in this thread,
A problem in either the front or the back could appear to be causing an issue in the other end,
As Fred says, missing align shims seems the biggest possibility based on your symptoms as far as the front,
Check close the REAR upper control arm frame mount wear pattern against the frame for possible ovaled frame holes - though that problem usually manifests itself more during accel/braking.
You didn't mention centerlink and it's a maint. item as well
I've seen a really really blown shock get the tire bouncing enough it loses all traction and causes wandering.
If you have not had it up in the air on stands then you need to. It's the only way to inspect close. Get a friend to eyeball everything too for stuff you might not notice.
Worst case you could have a bad balljoint or wallered out spindle hole.

GL Your wife should love that car, not fear it.
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