Unknown engine issue

Asked by Thomas Aug 19, 2017 at 03:58 AM about the 2007 Ford F-150 XL

Question type: Maintenance & Repair

I am experiencing a problem with my 2007 Ford F-150, V-6 4.2L 2wd. My
engine has no power, can barely get it to 50mph, it occasionally backfires,
some days more often, high gas consumption and a strong fuel smell from
exhaust. No one seems to be able to figure it out and was wondering if
anyone else has/is experiencing this problem. I have changed the 2 rear O2
sensors (can't get front ones off) replaced air filter, EGR valve and gave it a
tune-up. Still same problem. Any suggestions or help?

6 Answers

59,045

Have your coil pack tested. Make sure fuel injectors are clean. Do a full engine service including fuel & air filters, Spark plugs oem motorcraft, stay away from the plugs with hype. Use the better set of plug wires. Have your cat checked for clogs. If any check engine light are on tell us what the code set is. These engine have little vacuum boot elbows under the upper intake that either split or come off and need replaced often causing poor engine performance, the front one when bad causes mostly idle problems the rear one causes overall performance issues, both are hard to get too and neglected often, also the PCV is in the passengerside valve cover near firewall make sure it is seated properly and the vacuum hoses to it are in good shape and installed fully, it goes to rear underside upper intake also. Unless you have real tiny hands use mirrors, flashlights and tools to access the tight areas. May be a good idea to remove the throttle body to access the vacuum elbow on the one on the front underside and while its off take the IAC out and clean both the throttle body & IAC with CRC throttle body cleaner while using assorted nylon brushes (no Metal Brushes) reinstall with new gaskets. The thermostat is easy to change out also with throttle body off but I do not reccommend nothing but Motorcraft thermostats as replacements as the others are junk and your OEM original is likely fine. While checking the PCV clean it with the throttle body cleaner and its vacuum hose out real good. Also clean out the open upper intake while the throttlebody is off same deal just nylon brushes. The vacuum leaks on the upper intake also throw O2 sensor codes so thats likely why you changed them.

1 people found this helpful.
59,045

May need to use some bolt spray on the threads of those two front O2's, spray with different products until it comes loose without breaking it. Just spray and walk away and do so every now and then for a few weeks and give it a try one day.

59,045

Btw I added the full tune up and filter to the above for others sake as many people will read this need to know to do so, If you already replaced those as mention in question the disregard and also use dielectric grease on the inside of spark plug boots both ends.

2,565

If you have a Check Engine light that is on, have the codes read and let us know what they are... before replacing more parts!

I have a check engine light on, had codes pulled from a couple different places and they come up different. One is O2 sensors, one says running too lean. Had a mechanic check for leaks and said there are no leaks in vacuum. He suggested the parts I changed and also suggested the fuel pump and speed throttle as my speedometer has stopped also. Was thinking about bringing to Ford dealer to have them run the codes. I appreciate all y'alls help. I will get on spraying those upper sensors regularly.

Your Answer:

F-150

Looking for a Used F-150 in your area?

CarGurus has 13,512 nationwide F-150 listings starting at $3,888.

Postal Code:

CarGurus Experts

  • #1
    OJ
    Reputation
    41,860
  • #2
    Gene Arnett
    Reputation
    15,990
  • #3
    Rowefast
    Reputation
    15,480
View All

Find great deals from top-rated dealers

Search

Related Models For Sale

Used Chevrolet Silverado 1500
177 Great Deals out of 7,375 listings starting at $6,995
Used GMC Sierra 1500
143 Great Deals out of 7,815 listings starting at $5,500
Used Toyota Tundra
36 Great Deals out of 918 listings starting at $10,698
Used Ford F-250 Super Duty
28 Great Deals out of 750 listings starting at $3,990
Used Toyota Tacoma
41 Great Deals out of 786 listings starting at $9,975
Used Dodge RAM 1500
80 listings starting at $5,000
Used Ford Ranger
22 Great Deals out of 697 listings starting at $6,445
Used Ford Mustang
35 Great Deals out of 1,603 listings starting at $7,999
Used Chevrolet Silverado 2500HD
21 Great Deals out of 1,571 listings starting at $5,990
Used Ford Explorer
65 Great Deals out of 1,846 listings starting at $6,990
Used Chevrolet Colorado
44 Great Deals out of 1,142 listings starting at $4,995
Used GMC Sierra 2500HD
32 Great Deals out of 2,112 listings starting at $8,490

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.