# Ford Focus Surging/Bucking Between 40 and 50 MPH **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** focus, ford\ **Created:** [July 17, 2013, 6:07pm UTC](https://community.cartalk.com/t/ford-focus-surging-bucking-between-40-and-50-mph/80389 "2013-07-17T18:07:03Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![larrystew](https://avatars.discourse-cdn.com/v4/letter/l/7ea924/32.png) [@larrystew](https://community.cartalk.com/u/larrystew)\ **Post date:** [July 17, 2013, 6:07pm UTC](https://community.cartalk.com/t/ford-focus-surging-bucking-between-40-and-50-mph/80389/1 "2013-07-17T18:07:03Z")
My 2002 Ford Focus ZX5 has had a low idle (not unsteady) for about a year. Just thought I needed a tune-up. Recently, it started surging and bucking between 40 and 50 MPH. Seems to run fine under acceleration, but then when backing off the accelerator, it starts the surging/bucking. The check engine light is on constantly. A diagnostic pointed to the EGR valve, which I replaced, but it didn’t solve anything. Any ideas? ---
**Author:** ![RemcoW](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/remcow/32/2471_2.png) [@RemcoW](https://community.cartalk.com/u/RemcoW)\ **Post date:** [July 17, 2013, 6:44pm UTC](https://community.cartalk.com/t/ford-focus-surging-bucking-between-40-and-50-mph/80389/2 "2013-07-17T18:44:35Z")
I’d check your fuel pressure. You may want to replace the fuel filter. It may be due anyway, it is cheap and could easily cause what you are describing. ---
**Author:** ![larrystew](https://avatars.discourse-cdn.com/v4/letter/l/7ea924/32.png) [@larrystew](https://community.cartalk.com/u/larrystew)\ **Post date:** [July 21, 2013, 10:52pm UTC](https://community.cartalk.com/t/ford-focus-surging-bucking-between-40-and-50-mph/80389/3 "2013-07-21T22:52:08Z")
OK, fuel filter has been replaced. Problem still exists. It seems to now be surging/bucking as I’m accelerating from a stop. Once underway, it’s fine until I reach the 45-ish mph mark, then pulling back on the accelerator, it starts again. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [July 21, 2013, 11:22pm UTC](https://community.cartalk.com/t/ford-focus-surging-bucking-between-40-and-50-mph/80389/4 "2013-07-21T23:22:23Z")
The problem might be caused from a dirty Mass Air Flow sensor. Purchase a can of MAF sensor cleaner, remove the MAF sensor and spray down the wire inside the MAF sensor. Let the MAF sensor dry and reinstall it. Tester ---
**Author:** ![larrystew](https://avatars.discourse-cdn.com/v4/letter/l/7ea924/32.png) [@larrystew](https://community.cartalk.com/u/larrystew)\ **Post date:** [July 22, 2013, 4:55pm UTC](https://community.cartalk.com/t/ford-focus-surging-bucking-between-40-and-50-mph/80389/5 "2013-07-22T16:55:48Z")
Test, I did that about 6-8 months ago, thinking it would solve my low idle issue. No go. ☹