# Rough idle **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [May 21, 2009, 8:29pm UTC](https://community.cartalk.com/t/rough-idle/30793 "2009-05-21T20:29:37Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![dagcaclsnr](https://avatars.discourse-cdn.com/v4/letter/d/65b543/32.png) [@dagcaclsnr](https://community.cartalk.com/u/dagcaclsnr)\ **Post date:** [May 21, 2009, 8:29pm UTC](https://community.cartalk.com/t/rough-idle/30793/1 "2009-05-21T20:29:37Z")
I have a 2005 Ford F150 with the 3-valve 5.4 V8. Ford has warranted the fuel injectors for 120,000 miles, but will only replace injectors as they go bad. I have had one injector replaced by the dealer after the check-engine light came on. After that occurred I have used only top-tier gas (Chevron and Shell). The F150 currently has 55,000 miles on it and has been serviced regularly by a Ford dealer. Lately, there has been some rough idling similar to what happened when the injector was replaced, but with no check-engine light. I took it to the Ford dealer, they found no instances of miss-fires and are now trying to sell me on a $150 fuel system service (ie., [www.mocproducts.com](http://www.mocproducts.com)) . Would it be worth getting that service done? ---
**Author:** ![Beadsandbeads](https://avatars.discourse-cdn.com/v4/letter/b/c57346/32.png) [@Beadsandbeads](https://community.cartalk.com/u/Beadsandbeads)\ **Post date:** [May 21, 2009, 10:35pm UTC](https://community.cartalk.com/t/rough-idle/30793/2 "2009-05-21T22:35:56Z")
Your misfire has to be pretty substantial to turn on the engine light. YOur SOTP meter may well be more sensitive. They should be able to pick up misfire of a lesser extent with their code readers and it should be cylinder-specific. You get a misfire most often from either the injectors or coils (on plug). I don’t think you need that service. I think that you are worrying too much about what fuel you use too. You might buy some Techron and follow the instructions.