Jerks while going downhill on cruise control

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I have 114k miles on my 2002 4cyl (auto) Galant. Its a daily driver - bone stock. When the cruise is set and there is a downhill section on the road, the car begins to jerk every few (5-8) seconds. If I cancle the cruise control the engine brakes and generally there are no jerks (sometimes it does it though). It also jerks sometimes if I feather the throttle... much less than when the cruise is set. It accelerates smoothly.

The transmission seems to be good: recent flush and fluid change from the dealer, shifts smoothly, no jerks when I shift into R or D while parked, no slipping, pulls strong.

Other than that the car runs perfectly. Just got the timing belt changed as well and spark plugs were replaced about 15k miles ago.

Could it be due to bad spark plug wires? They are due for replacement. Is there any local parts store that sells NGK or do I need to order them online? Are BOSCH wires from Autozone any good?

Could it be due to EGR Valve? I've never replaced it since I got the car.

Any other ideas?

[DTP]

Vacuum leak?

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Any way to find the vacuum leak?

[Galanttuner10]

my 7g used to do that going downhill on cruise every so ofter on steeper hills, maybe to maintain speed??? now that im 5 speed i have no cruise so it doesnt do it anymore

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Its a daily driver/winter beater. I dont want to switch to manual. I have a Corvette for that :) Plus i want the cruise for highway driving. Any other ideas?

[Galanttuner10]

i didnt say switching to manual was the answer, i was showing it mostly has to do with the operation of the cruise control not with a vacuum leak. my car is my daily as well

[tamim13]

I don't think it's a vacuum leak. It's just the normal operation of the cruise control trying to control the speed set. When you are going downhill, gravity tends to increase your speed beyond what you have set, so the cruise control tries to control this and causes it to jerk as it does not have the ability to slow down the car in our 8g.

I have the same problem. I have just learned to live with it. I just turn it off and use the brakes. It's not the spark plugs or EGR because I have changed them all.

[01blackG]

I don't think it's a vacuum leak. It's just the normal operation of the cruise control trying to control the speed set. When you are going downhill, gravity tends to increase your speed beyond what you have set, so the cruise control tries to control this and causes it to jerk as it does not have the ability to slow down the car in our 8g.

I have the same problem. I have just learned to live with it. I just turn it off and use the brakes. It's not the spark plugs or EGR because I have changed them all.

DITO!!! But also you mention nothing about the engine mounts being checked. Look those over also just incase.