I just replaced the spark plugs and wires in my 99 f150 v6 4.2. 89k miles. They were in ok shape. Nothing that stood out at me. I replaced them with Bosch Platinum 2 and the AutoZone brand of wires.

Question is... It runs good and everything but when it idles, I now feel a shudder that I dont remember feeling before. Could this be from the plugs? I have read some on here about some plugs not working as well as others... Any ideas???

Thanks!

 

Chris,
I just put the Bosch Platinum plugs in my 4.2 two weeks ago. I noticed it idled slightly smoother, but other than that, no discernable change. I'd expect (but I might be wrong) that your "computer" would flag a problem with your plug(s) if there was one, and you'd get an idiot light warning.
This info probably isn't much help, but thought I'd pass it along anyways.

Brian A

 

Ford highly recommends using what came stock in your truck,most likely double platinum.Ive had several Ford techs tell me the same thing.I put Autolite DPs back in mine with Autolite pro series wires.Runs smooth as silk!

 

Hey FAT,

Do you know WHY Ford recommends replacement with the stock plug? It could be said that every (?) manufacturer will suggest replacement with factory (OEM) components, lubes, etc.
I have seen no difference in performance with the Bosch Platinum plugs. Except that it idles a little smoother (but that could be expected as the old plugs had 80,000 miles on them and were a little worse for the wear).
I wonder if there is something that I don't know, and even though my truck runs fine, something else (negative) might be going on. I doubt this is this case, but if it is I sure want to know about it so I can remedy the situation.
Without insulting anyone, I'm looking for SPECIFIC reasons as opposed to opinions or antecdotal stories. I will appreciate reading them, but am looking for something tangible, known, etc. that would dictate removal of the Bosch plugs and replacement with the same plugs that came from the factory.

Thanks!
Brian A

 

I just bought a 2003 F-150 4.2 V-6 last week, so I cannot say anything about that motor. My company vehicle was a 2000 Ford Ranger V.6 4.0 auto with 86,000 miles. At the 30,000 mile tune up that the fleet managment company recommended I took it to pep boys. They changed the plugs to Bosch platniums and the truck ran poorly. Ended up taking it to a Goodyear dealer that changed the plugs which they said were the wrong type of plug back to Ford Plugs and the engine ran smooth.

My 1997 Ranger that I traded in had 175,000 miles on it and I ran Bosch Plugs with no issues. I changed my plugs every 30,000 miles since at the time I had a large vehicle reimbursement package. The one thing I did notice was that I stuck with Ford wires due to the aftermarket wires never really worked right in my 1997 truck.

Most likely it could be the wires which you never know could be bad or just loose. If not recheck the gaps on your plugs.

 

Dont go near autozone wires. I bet that is your problem. You are better off with your old ford wires than new autozone ones. I got a set once just because they were out of a brand name and i needed them ASAP. long story short the engine ran horribly, half the wires came uncrimped and the resistance was through the roof. If you are wondering why they are about half the price of other brands its because they arent fit for a bicycle. Get a decent set of wires either from a ford dealer, NAPA (Belden makes a nice wire) or go back to autozone and get Bosch (the other brand they carry) plugs shouldnt matter too much if they are the specified plug and gap in any brand. Ford also recomends you put a dab of dieletrical grease in each wire when you install them.