1998 4.6, 79,000 miles. Recently began to get some valve/lifter noise while going into passing gear. No noise when when getting up to speed or running on cruise at 70 - 75. Only if you get on it after reaching about 55. I've always ran 87 octane. Will running a higher octane fix the clatter I get?

 

are you sure it valve lifter noise?? every car ive has that has loud lifters i could hear it all the time.

 

that's the only thing I can think of it being. sounds like a diesel.

 

running a higher octane would only fix it if it was knocking, even that may not fix that.

do you look for the gas or are you fixed with a certain brand? either way id go to a hess or sunoco (or other dependable company) and try their gas. you may just be using cheap gas. has it only done it on this tank or has it been going on for a while?

 

I have the same problem. It only makes the noise when I get on it. I don't hear it while gradualy accelerating or cruising. only during hard acceleration. I have always had it reguardless of where I fill up. I am running 93 now but, it is still there.

 

i have 97 4.6 with 128k no noises at all. always run 87 octane.if u think its valvetrain add a half a quart of tranny fluid to your oil, drive for about 20 miles, drain it and do a regular oil change. that might loosen up any stickiness in the valves etc..worked on my dodge that thing was tapping bad.

 

I always use Mobil gas...but will try something different. If no fix then I'll try the tranny oil. Thanks for the advice.

 

Sounds like spark knock. Try changing fuel vendors. Maybe you have some water in the tank ? Maybe time for plugs ?

-jeff b.

 

That's strange, theres something wrong, almost sounds like a timing thing. Does anyone have a 5.4L that has this problem? Or is it a 4.6L problem. I know there have been updates in programing for later models that may adjust timing parameters, you have to visit the dealer for that. My 98 5.4L never had this spark knock, if that's what it is. I'm also at 200,000 miles.

Somethings not right. I would call the dealership and inquire about updates for your model.

As spark plugs age and ware , the gap increases. If your plugs have some miles on them I would look there as well.

I would clean the throttle body, IAC and MAF as it effects fuel delivery. Check for leaks in the vac system and manifold gaskets as-well. I haven't heard of anyone having a fix for this one yet..

Good Luck.

 

could be a noisy injector try some cleaner in the tank that will also help if u have bed gas. i use sea foam treatment every 6k miles

 

It definitely sounds like preignition. You may want to try and decarbon your engine. I have seen carbon build up so thick that the carbon will start making contact with the cyl head. When carbon gets that thick you basicly increase your compression ratio. Sometimes enough that it can cause preignition with regular fuel. It can also generate a hot spot on the carbon and that will cause preignition too. We have had engines returned from the field with what sounded like lower end knock only to discover excessive carbon making contact with the cyl head cumbustion chamber. Just a thought.

 

2 Bottles of Gumout Regane to a full tank of Fuel. This should clean enough carbon to stop the preignition. If this doesnt work use a treatment of Sea Foam. Follow the Sea Foam Instructions carefully. This always worked on 5.2L / 5.9L Dodges which have no knock sensor.

If neither of these work I suspect you have an issue with the the knock sensor. For some reason it has become less sensitive. Could be that its defective, come loose, or needs its contact area cleaned.