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There are several technical service bulletins regarding a popping sound. Here is the one that seems to fit best with your description. Now, a number of these things have already been replaced. However, there are different components which have been revised based on build dates. Take a look through this TSB and let us know if any of it helps.
The attached picture is a list of part numbers.
2008 Ford Focus L4-2.0L
Suspension - Front End Pop/Click Noise On Bumps
Vehicle Steering and Suspension Suspension Stabilizer Bar Stabilizer Link Technical Service Bulletins By Symptom Suspension - Front End Pop/Click Noise On Bumps
SUSPENSION - FRONT END POP/CLICK NOISE ON BUMPS
TSB 10-8-5
CLICK/POP NOISE FROM FRONT END WHILE TURNING OR GOING OVER BUMPS
FORD:
2008-2010 Focus
This article supersedes TSB 09-18-2 to update the Service Procedure, Service Labor Time Standards and Part List.
ISSUE
Some 2008-2010 Focus vehicles may exhibit a click/pop type noise from the front end while turning and/or driving over bumps, or a creak/squeak noise from front when driving over bumps. The noise may be isolated to front stabilizer bar end links, front upper strut bearing area, and/or lower control arm.
ACTION
Follow the service procedure to correct the condition.
SERVICE PROCEDURE
1. Install Chassis Ear J5P97202 in the Rotunda Technician Tool Program or equivalent to identify and isolate the source of the noise.
2. Drive the vehicle over moderate bumps and perform left and right turns.
A. If a click/pop noise is coming from front stabilizer bar end link(s), proceed to Step 3.
B. If a click/pop noise is from upper strut bearing area, go to Step 4.
C. If a creak/squeak type noise is coming from a lower control arm, go to Step 5.
3. Front stabilizer bar end link click/pop noise.
A. Is vehicle built on or before 1/11/2010?
(1)Yes - remove and install four (4) revised stabilizer bar end link nuts per Workshop Manual (WSM), Section 204-01; torque to 46 lb-ft (63 N.M).
(2)No - replace affected stabilizer bar end link(s) per WSM, Section 204-01; torque nuts to 46 lb-ft (63 N.M).
4. Upper strut bearing click/pop noise.
A. Is vehicle built on or between 10/01/2007 and 10/31/2007?
(1)Yes - replace upper strut bearing per WSM, Section 204-01; torque nuts to 30 lb-ft (40 N.M).
(2)No - proceed to Step 3b.
B. Is vehicle built on or before 11/30/2008?
(1)Yes - inspect the three (3) upper strut mount nuts for signs of looseness. Torque nuts to 30 lb-ft (40 N.M).
(2)No - replace suspect strut per WSM, Section 204-01; torque upper nuts to 30 lb-ft (40 N.M).
5. Lower control arm creak/squeak noise.
A. Replace the affected lower control arm per WSM, Section 204-01.
Pic 1
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Take care,
Joe
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Thursday, August 15th, 2019 AT 10:06 PM