Misfire gets worse.. help!

7.4 99 (classic) fullsize.

I have a misfire getting worse and worse, at first it was just at speed but now its starting to misfire and backfire at idle.

I've replaced the plugs, leads, distributor cap, rotor, oil, trans fulid (to make sure when at speed it was not trans related).

After doing that if anything the problem has got worse.

There is a loud ticking noise coming from the engine bay, and occasional tapping on acceleration.

Before I start to pull the engine apart I wondered if someone might be able to suggest something with the ticking noise (apart form water pump bearings). I'm sure you know how frustraiting these kind of problems are, any help will be greatly appreciated.

Thanks,

Craig

It sounds like you need to pull your valve covers to start with and check your rocker arms-big blocks have always been bad about breaking them.

Do a compression check that will narrow it down to a specific cylinder.

yeah maybe you have piston slap, or maybe a bad cam could be causing the missing, it will get worse over time if the lobes start getting ground down. lol happened to the 350 in my truck

also, check for simple things, my buddy had one of his exhaust manifold gaskets go bad on him and it sounded just like an internal engine ticking noise lol.

Oil also could be too light or has a heavy mixture of gas and a carb air leak around the intake, or possibly an lifter thats too loose makeing the exhaust valve leak in the head...burned valve will also cause a backfire while running even in idle...mismatch plug wires or crossfiring...many possiblitiies for this problem....

I have a 1995 K1500 5.7L and it had a slight tap from the driver side. It gradually got worse and eventually impacted the engine performance. The symptoms included a lot of "misfiring" and sputtering above 20MPH. It sounded like a Model "T" and had no power.

It turned out to be the engine knock sensor was bad and the computer was retarding the timing to the point of misfire.

Hope you get it worked out!

JP

I have a 1995 K1500 5.7L and it had a slight tap from the driver side. It gradually got worse and eventually impacted the engine performance. The symptoms included a lot of "misfiring" and sputtering above 20MPH. It sounded like a Model "T" and had no power.

It turned out to be the engine knock sensor was bad and the computer was retarding the timing to the point of misfire.

Hope you get it worked out!

JP

Pull your distributor cap and make sure that there is not any side to side play in the distributor. This can cause a misfire. If there is side to side play you will need to replace the distributor, or put in a new shaft and bushings. Hope this helps.

I fixed it, well with some help, we stripped the whole ignition system down and rebuilt it all, cleaned everything (dis, leads, sensors, checked all plugs etc. etc.) and put it back together, runs better than ever now. I guess some things were just getting worn, dirty and loose. Strange though as most things were new.

Getting better MPG now too, really worth the work. Its like brand new.

Thanks for all the help, its good to know what might happen in the future, so i can take pre-emptive strikes.